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标题: MyBatis快速上手与知识点总结 [打印本页]

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作者: 勿忘初心做自己    时间: 2022-9-16 17:23
标题: MyBatis快速上手与知识点总结
目录

• 1、MyBatis概述
  
  
  
  • 1.1  MyBatis概述
    
  • 1.2  JDBC缺点
    
  • 1.3  MyBatis优化
    
  
  
• 2、MyBatis快速入门
  
• 3、Mapper代理开发
  
  
  
  • 3.1  Mapper代理开发概述
    
  • 3.2  使用Mapper代理要求
    
  • 3.3  案例代码实现
    
  
  
• 4、核心配置文件
  
  
  
  • 4.1  多环境配置
    
  • 4.2  类型别名
    
  
  
• 5、配置文件实现CRUD
  
  
  
  • 5.1 环境准备
    
  • 5.2 查询所有数据
    
  • 5.3 查询
    
  • 5.4 多条件查询
    
  • 5.6 添加数据与MyBatis事务
    
  • 5.7 修改
    
  • 5.8 删除数据
    
  • 5.9 MyBatis参数传递
    
  
  
• 6、通过注解实现CRUD
  

阅读提示：
本文默认已经预装预装maven

1、MyBatis概述

1.1  MyBatis概述

• 持久层框架，用于简化JDBC开发，是对JDBC的封装
  

  持久层：
  

  
  
  • 负责将数据保存到数据库的代码部分
    
  • Java EE三层架构：表现层、业务层、持久层
    

  
  

1.2  JDBC缺点

• 硬编码，不利于维护
  
  
  
  • 注册驱动、获取连接
    
  • SQL语句
    
  
  
• 操作繁琐
  
  
  
  • 手动设置参数
    
  • 手动封装结果集
    
  
  

1.3  MyBatis优化

• 硬编码 --> 配置文件
  
• 繁琐惭怍 --> 框架封装自动完成
  

2、MyBatis快速入门

• 需求：查询user表中的所有数据
  
• SQL
  1. create database mybatis;
  2. use mybatis;
  4. drop table if exists tb_user;
  6. create table tb_user(
  7.         id int primary key auto_increment,
  8.         username varchar(20),
  9.         password varchar(20),
  10.         gender char(1),
  11.         addr varchar(30)
  12. );
  14. INSERT INTO tb_user VALUES (1, 'zhangsan', '123', '男', '北京');
  15. INSERT INTO tb_user VALUES (2, '李四', '234', '女', '天津');
  16. INSERT INTO tb_user VALUES (3, '王五', '11', '男', '西安');

  复制代码
• 代码实现
  
  
  
  • 创建模块，导入坐标
    

    在pom.xml中配置文件中添加依赖的坐标
    注意：需要在项目的resources目录下创建logback的配置文件
    

    1. <dependencies>
    2. <mappers>
    3.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    4. </mappers>
    5. <mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers><dependency>
    8. <mappers>
    9.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    10. </mappers><mappers>
    11.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    12. </mappers><groupId>org.mybatis</groupId>
    13. <mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers><mappers>
    16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    17. </mappers><artifactId>mybatis</artifactId>
    18. <mappers>
    19.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    20. </mappers><mappers>
    21.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    22. </mappers><version>3.5.5</version>
    23. <mappers>
    24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    25. </mappers></dependency>
    26. <mappers>
    27.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    28. </mappers>
    29. <mappers>
    30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    31. </mappers><dependency>
    32. <mappers>
    33.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    34. </mappers><mappers>
    35.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    36. </mappers><groupId>mysql</groupId>
    37. <mappers>
    38.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    39. </mappers><mappers>
    40.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    41. </mappers><artifactId>mysql-connector-java</artifactId>
    42. <mappers>
    43.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    44. </mappers><mappers>
    45.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    46. </mappers><version>5.1.46</version>
    47. <mappers>
    48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    49. </mappers></dependency>
    50. <mappers>
    51.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    52. </mappers>
    53. <mappers>
    54.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    55. </mappers><dependency>
    56. <mappers>
    57.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    58. </mappers><mappers>
    59.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    60. </mappers><groupId>junit</groupId>
    61. <mappers>
    62.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    63. </mappers><mappers>
    64.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    65. </mappers><artifactId>junit</artifactId>
    66. <mappers>
    67.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    68. </mappers><mappers>
    69.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    70. </mappers><version>4.13</version>
    71. <mappers>
    72.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    73. </mappers><mappers>
    74.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    75. </mappers><scope>test</scope>
    76. <mappers>
    77.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    78. </mappers></dependency>
    79. <mappers>
    80.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    81. </mappers>
    82. <mappers>
    83.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    84. </mappers><dependency>
    85. <mappers>
    86.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    87. </mappers><mappers>
    88.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    89. </mappers><groupId>org.slf4j</groupId>
    90. <mappers>
    91.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    92. </mappers><mappers>
    93.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    94. </mappers><artifactId>slf4j-api</artifactId>
    95. <mappers>
    96.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    97. </mappers><mappers>
    98.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    99. </mappers><version>1.7.20</version>
    100. <mappers>
    101.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    102. </mappers></dependency>
    103. <mappers>
    104.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    105. </mappers>
    106. <mappers>
    107.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    108. </mappers><dependency>
    109. <mappers>
    110.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    111. </mappers><mappers>
    112.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    113. </mappers><groupId>ch.qos.logback</groupId>
    114. <mappers>
    115.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    116. </mappers><mappers>
    117.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    118. </mappers><artifactId>logback-classic</artifactId>
    119. <mappers>
    120.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    121. </mappers><mappers>
    122.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    123. </mappers><version>1.2.3</version>
    124. <mappers>
    125.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    126. </mappers></dependency>
    127. <mappers>
    128.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    129. </mappers>
    130. <mappers>
    131.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    132. </mappers><dependency>
    133. <mappers>
    134.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    135. </mappers><mappers>
    136.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    137. </mappers><groupId>ch.qos.logback</groupId>
    138. <mappers>
    139.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    140. </mappers><mappers>
    141.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    142. </mappers><artifactId>logback-core</artifactId>
    143. <mappers>
    144.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    145. </mappers><mappers>
    146.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    147. </mappers><version>1.2.3</version>
    148. <mappers>
    149.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    150. </mappers></dependency>
    151. </dependencies>

    复制代码
  • 编写MyBatis核心文件
    

    核心文件用于替换信息，解决硬编码问题
    在模块下的resources目录下创建mybatis的配置文件mybatis-config.xml
    

    1. <?xml version="1.0" encoding="UTF-8" ?>
    2. <!DOCTYPE configuration
    3. <mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers><mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
    8. <mappers>
    9.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    10. </mappers><mappers>
    11.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    12. </mappers>"http://mybatis.org/dtd/mybatis-3-config.dtd">
    13. <configuration>
    14. <mappers>
    15.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    16. </mappers><environments default="development">
    17. <mappers>
    18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    19. </mappers><mappers>
    20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    21. </mappers><environment id="development">
    22. <mappers>
    23.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    24. </mappers><mappers>
    25.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    26. </mappers><mappers>
    27.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    28. </mappers>
    29. <mappers>
    30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    31. </mappers><mappers>
    32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    33. </mappers><mappers>
    34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    35. </mappers><transactionManager type="JDBC"/>
    36. <mappers>
    37.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    38. </mappers><mappers>
    39.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    40. </mappers><mappers>
    41.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    42. </mappers>
    43. <mappers>
    44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    45. </mappers><mappers>
    46.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    47. </mappers><mappers>
    48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    49. </mappers><dataSource type="POOLED">
    50. <mappers>
    51.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    52. </mappers><mappers>
    53.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    54. </mappers><mappers>
    55.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    56. </mappers><mappers>
    57.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    58. </mappers><property name="driver" value="com.mysql.jdbc.Driver"/>
    59. <mappers>
    60.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    61. </mappers><mappers>
    62.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    63. </mappers><mappers>
    64.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    65. </mappers><mappers>
    66.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    67. </mappers><property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
    68. <mappers>
    69.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    70. </mappers><mappers>
    71.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    72. </mappers><mappers>
    73.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    74. </mappers><mappers>
    75.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    76. </mappers><property name="username" value="root"/>
    77. <mappers>
    78.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    79. </mappers><mappers>
    80.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    81. </mappers><mappers>
    82.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    83. </mappers><mappers>
    84.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    85. </mappers><property name="password" value="123456"/>
    86. <mappers>
    87.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    88. </mappers><mappers>
    89.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    90. </mappers><mappers>
    91.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    92. </mappers></dataSource>
    93. <mappers>
    94.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    95. </mappers><mappers>
    96.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    97. </mappers></environment>
    98. <mappers>
    99.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    100. </mappers></environments>
    101. <mappers>
    102.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    103. </mappers>
    104. <mappers>
    105.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    106. </mappers><mappers>
    107. <mappers>
    108.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    109. </mappers><mappers>
    110.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    111. </mappers><mapper resource="UserMapper.xml"/>
    112. <mappers>
    113.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    114. </mappers></mappers>
    115. </configuration>

    复制代码
  • 编写SQL映射文件
    

    SQL映射文件用于统一管理SQL语句，解决硬编码问题
    在模块的resources目录下创建映射配置文件UserMaooer.xml
    

    1. <?xml version="1.0" encoding="UTF-8" ?>
    2. <!DOCTYPE mapper
    3. <mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers><mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    8. <mappers>
    9.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    10. </mappers><mappers>
    11.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    12. </mappers>"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    14. <mapper namespace="test">
    15. <mappers>
    16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    17. </mappers>
    18. <mappers>
    19.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    20. </mappers><select id="selectAll" resultType="priv.dandelion.entity.User">
    21. <mappers>
    22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    23. </mappers><mappers>
    24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    25. </mappers>select * from tb_user;
    26. <mappers>
    27.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    28. </mappers></select>
    29. </mapper>

    复制代码
  • 编码
    
    
    
    • 实体类
      1. package priv.dandelion.entity;
      3. public class User {
      5. <mappers>
      6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      7. </mappers>private Integer id;
      8. <mappers>
      9.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      10. </mappers>private String username;
      11. <mappers>
      12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      13. </mappers>private String password;
      14. <mappers>
      15.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      16. </mappers>private String gender;
      17. <mappers>
      18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      19. </mappers>private String address;
      21. <mappers>
      22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      23. </mappers>public User() {
      24. <mappers>
      25.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      26. </mappers>}
      28. <mappers>
      29.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      30. </mappers>public User(Integer id, String username, String password, String gender, String address) {
      31. <mappers>
      32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      33. </mappers><mappers>
      34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      35. </mappers>this.id = id;
      36. <mappers>
      37.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      38. </mappers><mappers>
      39.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      40. </mappers>this.username = username;
      41. <mappers>
      42.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      43. </mappers><mappers>
      44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      45. </mappers>this.password = password;
      46. <mappers>
      47.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      48. </mappers><mappers>
      49.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      50. </mappers>this.gender = gender;
      51. <mappers>
      52.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      53. </mappers><mappers>
      54.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      55. </mappers>this.address = address;
      56. <mappers>
      57.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      58. </mappers>}
      60. <mappers>
      61.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      62. </mappers>public Integer getId() {
      63. <mappers>
      64.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      65. </mappers><mappers>
      66.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      67. </mappers>return id;
      68. <mappers>
      69.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      70. </mappers>}
      72. <mappers>
      73.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      74. </mappers>public void setId(Integer id) {
      75. <mappers>
      76.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      77. </mappers><mappers>
      78.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      79. </mappers>this.id = id;
      80. <mappers>
      81.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      82. </mappers>}
      84. <mappers>
      85.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      86. </mappers>public String getUsername() {
      87. <mappers>
      88.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      89. </mappers><mappers>
      90.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      91. </mappers>return username;
      92. <mappers>
      93.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      94. </mappers>}
      96. <mappers>
      97.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      98. </mappers>public void setUsername(String username) {
      99. <mappers>
      100.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      101. </mappers><mappers>
      102.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      103. </mappers>this.username = username;
      104. <mappers>
      105.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      106. </mappers>}
      108. <mappers>
      109.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      110. </mappers>public String getPassword() {
      111. <mappers>
      112.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      113. </mappers><mappers>
      114.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      115. </mappers>return password;
      116. <mappers>
      117.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      118. </mappers>}
      120. <mappers>
      121.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      122. </mappers>public void setPassword(String password) {
      123. <mappers>
      124.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      125. </mappers><mappers>
      126.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      127. </mappers>this.password = password;
      128. <mappers>
      129.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      130. </mappers>}
      132. <mappers>
      133.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      134. </mappers>public String getGender() {
      135. <mappers>
      136.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      137. </mappers><mappers>
      138.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      139. </mappers>return gender;
      140. <mappers>
      141.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      142. </mappers>}
      144. <mappers>
      145.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      146. </mappers>public void setGender(String gender) {
      147. <mappers>
      148.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      149. </mappers><mappers>
      150.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      151. </mappers>this.gender = gender;
      152. <mappers>
      153.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      154. </mappers>}
      156. <mappers>
      157.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      158. </mappers>public String getAddress() {
      159. <mappers>
      160.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      161. </mappers><mappers>
      162.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      163. </mappers>return address;
      164. <mappers>
      165.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      166. </mappers>}
      168. <mappers>
      169.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      170. </mappers>public void setAddress(String address) {
      171. <mappers>
      172.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      173. </mappers><mappers>
      174.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      175. </mappers>this.address = address;
      176. <mappers>
      177.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      178. </mappers>}
      180. <mappers>
      181.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      182. </mappers>@Override
      183. <mappers>
      184.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      185. </mappers>public String toString() {
      186. <mappers>
      187.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      188. </mappers><mappers>
      189.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      190. </mappers>return "User{" +
      191. <mappers>
      192.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      193. </mappers><mappers>
      194.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      195. </mappers><mappers>
      196.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      197. </mappers><mappers>
      198.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      199. </mappers>"id=" + id +
      200. <mappers>
      201.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      202. </mappers><mappers>
      203.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      204. </mappers><mappers>
      205.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      206. </mappers><mappers>
      207.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      208. </mappers>", username='" + username + '\'' +
      209. <mappers>
      210.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      211. </mappers><mappers>
      212.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      213. </mappers><mappers>
      214.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      215. </mappers><mappers>
      216.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      217. </mappers>", password='" + password + '\'' +
      218. <mappers>
      219.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      220. </mappers><mappers>
      221.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      222. </mappers><mappers>
      223.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      224. </mappers><mappers>
      225.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      226. </mappers>", gender='" + gender + '\'' +
      227. <mappers>
      228.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      229. </mappers><mappers>
      230.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      231. </mappers><mappers>
      232.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      233. </mappers><mappers>
      234.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      235. </mappers>", address='" + address + '\'' +
      236. <mappers>
      237.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      238. </mappers><mappers>
      239.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      240. </mappers><mappers>
      241.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      242. </mappers><mappers>
      243.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      244. </mappers>'}';
      245. <mappers>
      246.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      247. </mappers>}
      248. }

      复制代码
    • 测试类
      1. public static void main(String[] args) throws IOException {
      2. <mappers>
      3.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      4. </mappers>// 加载mybatis的核心配置文件，获取SqlSessionFactory
      5. <mappers>
      6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      7. </mappers>String resource = "mybatis-config.xml";
      8. <mappers>
      9.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      10. </mappers>InputStream inputStream = Resources.getResourceAsStream(resource);
      11. <mappers>
      12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      13. </mappers>SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
      14. <mappers>
      15.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      16. </mappers>// 获取Session对象，执行SQL语句
      17. <mappers>
      18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      19. </mappers>SqlSession sqlSession = sqlSessionFactory.openSession();
      20. <mappers>
      21.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      22. </mappers>// 执行SQL，处理结果
      23. <mappers>
      24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      25. </mappers>List<User> users = sqlSession.selectList("test.selectAll");
      26. <mappers>
      27.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      28. </mappers>System.out.println(users);
      29. <mappers>
      30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      31. </mappers>// 释放资源
      32. <mappers>
      33.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      34. </mappers>sqlSession.close();
      35. }

      复制代码
    
    
  
  

3、Mapper代理开发

3.1  Mapper代理开发概述

解决形如上述测试类中List users = sqlSession.selectList("test.selectAll");的硬编码问题

• 解决原生方式中的硬编码
  
• 简化后期的SQL执行
  

3.2  使用Mapper代理要求

• 定义与SQL映射文件同名的Mapper接口，并且将Mapper接口和SQL映射文件放置在同一目录下
  

  maven项目开发时要求code和resources分开，可在resources中创建相同包文件来是实现上述效果
  

  
  
• 设置SQL映射文件的namespace属性未Mapper接口的全限定名
  
• 在Mapper接口中定义方法，方法名就是SQL映射文件中SQL语句的id，并且参数类型和返回值类型一致
  

3.3  案例代码实现

• 修改SQL映射文件UserMapper.xml
  

  同时还要修改其路径
  

  1. <?xml version="1.0" encoding="UTF-8" ?>
  2. <!DOCTYPE mapper
  3. <mappers>
  4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  5. </mappers><mappers>
  6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  7. </mappers>PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  8. <mappers>
  9.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  10. </mappers><mappers>
  11.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  12. </mappers>"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  14. <mapper namespace="priv.dandelion.mapper.UserMapper">
  15. <mappers>
  16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  17. </mappers><select id="selectAll" resultType="priv.dandelion.entity.User">
  18. <mappers>
  19.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  20. </mappers><mappers>
  21.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  22. </mappers>select * from tb_user;
  23. <mappers>
  24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  25. </mappers></select>
  26. </mapper>

  复制代码
• 创建对应的Mapper接口UserMapper.interface
  1. public interface UserMapper {
  2. <mappers>
  3.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  4. </mappers>List<User> selectAll();
  5. }

  复制代码
• 修改mybatis核心配置文件中加载SQL映射的的路径
  1. <mappers>
  2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  3. </mappers>

  复制代码
• 测试代码
  1. public static void main(String[] args) throws IOException {<mappers>
  2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  3. </mappers>// 加载mybatis的核心配置文件，获取SqlSessionFactory<mappers>
  4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  5. </mappers>String resource = "mybatis-config.xml";<mappers>
  6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  7. </mappers>InputStream inputStream = Resources.getResourceAsStream(resource);<mappers>
  8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  9. </mappers>SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);<mappers>
  10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  11. </mappers>// 获取Session对象，执行SQL语句<mappers>
  12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  13. </mappers>SqlSession sqlSession = sqlSessionFactory.openSession();<mappers>
  14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  15. </mappers>// 执行SQL，处理结果<mappers>
  16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  17. </mappers>// 获取UserMapper接口的代理对象<mappers>
  18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  19. </mappers>UserMapper userMapper = sqlSession.getMapper(UserMapper.class);<mappers>
  20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  21. </mappers>List users = userMapper.selectAll();<mappers>
  22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  23. </mappers>System.out.println(users);<mappers>
  24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  25. </mappers>// 释放资源<mappers>
  26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  27. </mappers>sqlSession.close();}

  复制代码
• 改进
  

  如果Mapper接口名称和SQL映射文件名称相同，并在同一目录下，则可以使用包扫描的方式简化SQL映射文件的加载，简化mybatis核心配置文件
  

  1. <mappers>
  2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  3. </mappers><mappers>
  4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  5. </mappers><mappers>
  6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  7. </mappers><mappers>
  8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  9. </mappers>

  复制代码

4、核心配置文件

4.1  多环境配置

在核心配置文件的 environments 标签中其实是可以配置多个 environment ，使用 id 给每段环境起名，在 environments 中使用 default='环境id' 来指定使用哪儿段配置。我们一般就配置一个 environment 即可

1. <?xml version="1.0" encoding="UTF-8" ?>
2. <!DOCTYPE configuration
3. <mappers>
4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
5. </mappers><mappers>
6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
7. </mappers>PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
8. <mappers>
9.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
10. </mappers><mappers>
11.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
12. </mappers>"http://mybatis.org/dtd/mybatis-3-config.dtd">
13. <configuration>
14. <mappers>
15.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
16. </mappers><environments default="development">
17. <mappers>
18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
19. </mappers><mappers>
20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
21. </mappers><environment id="development">
22. <mappers>
23.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
24. </mappers><mappers>
25.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
26. </mappers><mappers>
27.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
28. </mappers>
29. <mappers>
30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
31. </mappers><mappers>
32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
33. </mappers><mappers>
34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
35. </mappers><transactionManager type="JDBC"/>
36. <mappers>
37.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
38. </mappers><mappers>
39.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
40. </mappers><mappers>
41.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
42. </mappers>
43. <mappers>
44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
45. </mappers><mappers>
46.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
47. </mappers><mappers>
48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
49. </mappers><dataSource type="POOLED">
50. <mappers>
51.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
52. </mappers><mappers>
53.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
54. </mappers><mappers>
55.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
56. </mappers><mappers>
57.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
58. </mappers><property name="driver" value="com.mysql.jdbc.Driver"/>
59. <mappers>
60.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
61. </mappers><mappers>
62.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
63. </mappers><mappers>
64.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
65. </mappers><mappers>
66.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
67. </mappers><property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
68. <mappers>
69.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
70. </mappers><mappers>
71.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
72. </mappers><mappers>
73.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
74. </mappers><mappers>
75.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
76. </mappers><property name="username" value="root"/>
77. <mappers>
78.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
79. </mappers><mappers>
80.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
81. </mappers><mappers>
82.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
83. </mappers><mappers>
84.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
85. </mappers><property name="password" value="123456"/>
86. <mappers>
87.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
88. </mappers><mappers>
89.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
90. </mappers><mappers>
91.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
92. </mappers></dataSource>
93. <mappers>
94.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
95. </mappers><mappers>
96.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
97. </mappers></environment>
98. <mappers>
99.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
100. </mappers></environments>
101. <mappers>
102.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
103. </mappers>
104. <mappers>
105.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
106. </mappers><mappers>
107. <mappers>
108.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
109. </mappers><mappers>
110.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
111. </mappers><mapper resource="UserMapper.xml"/>
112. <mappers>
113.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
114. </mappers></mappers>
115. </configuration><?xml version="1.0" encoding="UTF-8" ?>
116. <!DOCTYPE configuration
117. <mappers>
118.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
119. </mappers><mappers>
120.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
121. </mappers>PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
122. <mappers>
123.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
124. </mappers><mappers>
125.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
126. </mappers>"http://mybatis.org/dtd/mybatis-3-config.dtd">
127. <configuration>
128. <mappers>
129.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
130. </mappers><environments default="development">
131. <mappers>
132.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
133. </mappers><mappers>
134.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
135. </mappers><environment id="development">
136. <mappers>
137.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
138. </mappers><mappers>
139.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
140. </mappers><mappers>
141.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
142. </mappers>
143. <mappers>
144.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
145. </mappers><mappers>
146.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
147. </mappers><mappers>
148.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
149. </mappers><transactionManager type="JDBC"/>
150. <mappers>
151.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
152. </mappers><mappers>
153.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
154. </mappers><mappers>
155.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
156. </mappers>
157. <mappers>
158.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
159. </mappers><mappers>
160.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
161. </mappers><mappers>
162.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
163. </mappers><dataSource type="POOLED">
164. <mappers>
165.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
166. </mappers><mappers>
167.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
168. </mappers><mappers>
169.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
170. </mappers><mappers>
171.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
172. </mappers><property name="driver" value="com.mysql.jdbc.Driver"/>
173. <mappers>
174.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
175. </mappers><mappers>
176.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
177. </mappers><mappers>
178.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
179. </mappers><mappers>
180.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
181. </mappers><property name="url" value="jdbc:mysql:///mybatis?useSSL=false"/>
182. <mappers>
183.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
184. </mappers><mappers>
185.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
186. </mappers><mappers>
187.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
188. </mappers><mappers>
189.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
190. </mappers><property name="username" value="root"/>
191. <mappers>
192.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
193. </mappers><mappers>
194.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
195. </mappers><mappers>
196.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
197. </mappers><mappers>
198.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
199. </mappers><property name="password" value="123456"/>
200. <mappers>
201.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
202. </mappers><mappers>
203.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
204. </mappers><mappers>
205.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
206. </mappers></dataSource>
207. <mappers>
208.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
209. </mappers><mappers>
210.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
211. </mappers></environment>
212. <mappers>
213.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
214. </mappers></environments>
215. <mappers>
216.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
217. </mappers>
218. <mappers>
219.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
220. </mappers><mappers>
221. <mappers>
222.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
223. </mappers><mappers>
224.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
225. </mappers><mapper resource="UserMapper.xml"/>
226. <mappers>
227.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
228. </mappers></mappers>
229. </configuration>

复制代码

4.2  类型别名

映射配置文件中的resultType属性需要配置数据封装的类型（类的全限定名），繁琐
Mybatis 提供了 类型别名(typeAliases) 可以简化这部分的书写

1. <mappers>
2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
3. </mappers><mappers>
4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
5. </mappers><mappers>
6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
7. </mappers><mappers>
8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
9. </mappers><mappers>
10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
11. </mappers>

复制代码

1. <?xml version="1.0" encoding="UTF-8" ?>
2. <!DOCTYPE mapper
3. <mappers>
4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
5. </mappers><mappers>
6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
7. </mappers>PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
8. <mappers>
9.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
10. </mappers><mappers>
11.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
12. </mappers>"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
14. <mapper namespace="test">
15. <mappers>
16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
17. </mappers>
18. <mappers>
19.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
20. </mappers><select id="selectAll" resultType="priv.dandelion.entity.User">
21. <mappers>
22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
23. </mappers><mappers>
24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
25. </mappers>select * from tb_user;
26. <mappers>
27.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
28. </mappers></select>
29. </mapper>

复制代码

5、配置文件实现CRUD

5.1 环境准备

• SQL
  1. -- 删除tb_brand表drop table if exists tb_brand;-- 创建tb_brand表create table tb_brand(<mappers>
  2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  3. </mappers>-- id 主键<mappers>
  4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  5. </mappers>id<mappers>
  6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  7. </mappers><mappers>
  8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  9. </mappers>   int primary key auto_increment,<mappers>
  10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  11. </mappers>-- 品牌名称<mappers>
  12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  13. </mappers>brand_name   varchar(20),<mappers>
  14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  15. </mappers>-- 企业名称<mappers>
  16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  17. </mappers>company_name varchar(20),<mappers>
  18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  19. </mappers>-- 排序字段<mappers>
  20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  21. </mappers>ordered<mappers>
  22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  23. </mappers>  int,<mappers>
  24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  25. </mappers>-- 描述信息<mappers>
  26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  27. </mappers>description  varchar(100),<mappers>
  28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  29. </mappers>-- 状态：0：禁用  1：启用<mappers>
  30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  31. </mappers>status<mappers>
  32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  33. </mappers>   int);-- 添加数据insert into tb_brand (brand_name, company_name, ordered, description, status)values ('三只松鼠', '三只松鼠股份有限公司', 5, '好吃不上火', 0),<mappers>
  34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  35. </mappers>   ('华为', '华为技术有限公司', 100, '华为致力于把数字世界带入每个人、每个家庭、每个组织，构建万物互联的智能世界', 1),<mappers>
  36.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  37. </mappers>   ('小米', '小米科技有限公司', 50, 'are you ok', 1);SELECT * FROM tb_brand;

  复制代码
• 实体类
  1. public class Brand {<mappers>
  2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  3. </mappers><mappers>
  4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  5. </mappers>private Integer id;<mappers>
  6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  7. </mappers>private String brand_name;<mappers>
  8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  9. </mappers>private String company_name;<mappers>
  10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  11. </mappers>private Integer ordered;<mappers>
  12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  13. </mappers>private String description;<mappers>
  14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  15. </mappers>private Integer status;<mappers>
  16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  17. </mappers>public Brand() {<mappers>
  18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  19. </mappers>}<mappers>
  20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  21. </mappers>public Brand(<mappers>
  22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  23. </mappers><mappers>
  24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  25. </mappers><mappers>
  26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  27. </mappers>Integer id,<mappers>
  28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  29. </mappers><mappers>
  30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  31. </mappers><mappers>
  32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  33. </mappers>String brand_name,<mappers>
  34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  35. </mappers><mappers>
  36.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  37. </mappers><mappers>
  38.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  39. </mappers>String company_name,<mappers>
  40.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  41. </mappers><mappers>
  42.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  43. </mappers><mappers>
  44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  45. </mappers>Integer ordered,<mappers>
  46.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  47. </mappers><mappers>
  48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  49. </mappers><mappers>
  50.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  51. </mappers>String description,<mappers>
  52.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  53. </mappers><mappers>
  54.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  55. </mappers><mappers>
  56.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  57. </mappers>Integer status<mappers>
  58.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  59. </mappers>) {<mappers>
  60.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  61. </mappers><mappers>
  62.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  63. </mappers>this.id = id;<mappers>
  64.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  65. </mappers><mappers>
  66.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  67. </mappers>this.brand_name = brand_name;<mappers>
  68.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  69. </mappers><mappers>
  70.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  71. </mappers>this.company_name = company_name;<mappers>
  72.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  73. </mappers><mappers>
  74.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  75. </mappers>this.ordered = ordered;<mappers>
  76.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  77. </mappers><mappers>
  78.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  79. </mappers>this.description = description;<mappers>
  80.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  81. </mappers><mappers>
  82.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  83. </mappers>this.status = status;<mappers>
  84.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  85. </mappers>}<mappers>
  86.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  87. </mappers>public Integer getId() {<mappers>
  88.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  89. </mappers><mappers>
  90.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  91. </mappers>return id;<mappers>
  92.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  93. </mappers>}<mappers>
  94.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  95. </mappers>public void setId(Integer id) {<mappers>
  96.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  97. </mappers><mappers>
  98.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  99. </mappers>this.id = id;<mappers>
  100.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  101. </mappers>}<mappers>
  102.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  103. </mappers>public String getBrand_name() {<mappers>
  104.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  105. </mappers><mappers>
  106.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  107. </mappers>return brand_name;<mappers>
  108.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  109. </mappers>}<mappers>
  110.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  111. </mappers>public void setBrand_name(String brand_name) {<mappers>
  112.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  113. </mappers><mappers>
  114.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  115. </mappers>this.brand_name = brand_name;<mappers>
  116.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  117. </mappers>}<mappers>
  118.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  119. </mappers>public String getCompany_name() {<mappers>
  120.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  121. </mappers><mappers>
  122.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  123. </mappers>return company_name;<mappers>
  124.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  125. </mappers>}<mappers>
  126.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  127. </mappers>public void setCompany_name(String company_name) {<mappers>
  128.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  129. </mappers><mappers>
  130.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  131. </mappers>this.company_name = company_name;<mappers>
  132.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  133. </mappers>}<mappers>
  134.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  135. </mappers>public Integer getOrdered() {<mappers>
  136.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  137. </mappers><mappers>
  138.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  139. </mappers>return ordered;<mappers>
  140.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  141. </mappers>}<mappers>
  142.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  143. </mappers>public void setOrdered(Integer ordered) {<mappers>
  144.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  145. </mappers><mappers>
  146.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  147. </mappers>this.ordered = ordered;<mappers>
  148.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  149. </mappers>}<mappers>
  150.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  151. </mappers>public String getDescription() {<mappers>
  152.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  153. </mappers><mappers>
  154.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  155. </mappers>return description;<mappers>
  156.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  157. </mappers>}<mappers>
  158.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  159. </mappers>public void setDescription(String description) {<mappers>
  160.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  161. </mappers><mappers>
  162.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  163. </mappers>this.description = description;<mappers>
  164.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  165. </mappers>}<mappers>
  166.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  167. </mappers>public Integer getStatus() {<mappers>
  168.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  169. </mappers><mappers>
  170.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  171. </mappers>return status;<mappers>
  172.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  173. </mappers>}<mappers>
  174.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  175. </mappers>public void setStatus(Integer status) {<mappers>
  176.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  177. </mappers><mappers>
  178.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  179. </mappers>this.status = status;<mappers>
  180.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  181. </mappers>}<mappers>
  182.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  183. </mappers>@Override<mappers>
  184.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  185. </mappers>public String toString() {<mappers>
  186.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  187. </mappers><mappers>
  188.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  189. </mappers>return "Brand{" +<mappers>
  190.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  191. </mappers><mappers>
  192.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  193. </mappers><mappers>
  194.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  195. </mappers><mappers>
  196.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  197. </mappers>"id=" + id +<mappers>
  198.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  199. </mappers><mappers>
  200.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  201. </mappers><mappers>
  202.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  203. </mappers><mappers>
  204.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  205. </mappers>", brand_name='" + brand_name + '\'' +<mappers>
  206.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  207. </mappers><mappers>
  208.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  209. </mappers><mappers>
  210.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  211. </mappers><mappers>
  212.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  213. </mappers>", company_name='" + company_name + '\'' +<mappers>
  214.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  215. </mappers><mappers>
  216.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  217. </mappers><mappers>
  218.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  219. </mappers><mappers>
  220.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  221. </mappers>", ordered=" + ordered +<mappers>
  222.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  223. </mappers><mappers>
  224.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  225. </mappers><mappers>
  226.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  227. </mappers><mappers>
  228.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  229. </mappers>", description='" + description + '\'' +<mappers>
  230.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  231. </mappers><mappers>
  232.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  233. </mappers><mappers>
  234.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  235. </mappers><mappers>
  236.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  237. </mappers>", status=" + status +<mappers>
  238.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  239. </mappers><mappers>
  240.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  241. </mappers><mappers>
  242.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  243. </mappers><mappers>
  244.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  245. </mappers>'}';<mappers>
  246.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  247. </mappers>}}

  复制代码
• 安装插件MyBatisX
  
• 步骤
  

  
  
  • 编写接口方法Mapper接口
    
    
    
    • 参数
      
    • 返回值
      
    
    
  • 在SQL映射文件中编写SQL语句
    
    
    
    • MyBatisX插件自动补全
      
    • 编写SQL
      
    • 若数据库字段名和实体类字段名不同，则需要解决该问题（见 5.2 SQL映射文件）
      
    
    
  • 编写执行测试
    
    
    
    • 获取SqlSessionFactory
      
    • 获取sqlSession对象
      
    • 获取mapper接口的代理对象
      
    • 执行方法
      
    • 释放资源
      
    
    

  
  

5.2 查询所有数据

本节要点：

• 测试类的编写方式
  
• 解决数据库字段和实体类字段名不同的问题
  

• 编写接口方法
  1. public interface BrandMapper {<mappers>
  2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  3. </mappers>public List selectAll();}

  复制代码
• 编写SQL映射文件
  1. <mappers>
  2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  3. </mappers><mappers>
  4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  5. </mappers><mappers>
  6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  7. </mappers><mappers>
  8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  9. </mappers><mappers>
  10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  11. </mappers><mappers>
  12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  13. </mappers><mappers>
  14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  15. </mappers><mappers>
  16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  17. </mappers><mappers>
  18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  19. </mappers><mappers>
  20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  21. </mappers><mappers>
  22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  23. </mappers>select *<mappers>
  24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  25. </mappers><mappers>
  26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  27. </mappers>from tb_brand;<mappers>
  28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  29. </mappers>

  复制代码
• 编写测试方法
  1. @Testpublic void testSelectAll() throws IOException {<mappers>
  2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  3. </mappers>// 获取SqlSessionFactory<mappers>
  4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  5. </mappers>String resource = "mybatis-config.xml";<mappers>
  6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  7. </mappers>InputStream inputStream = Resources.getResourceAsStream(resource);<mappers>
  8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  9. </mappers>SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);<mappers>
  10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  11. </mappers>// 获取sqlSession对象<mappers>
  12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  13. </mappers>SqlSession sqlSession = sqlSessionFactory.openSession();<mappers>
  14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  15. </mappers>// 获取mapper接口的代理对象<mappers>
  16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  17. </mappers>BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);<mappers>
  18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  19. </mappers>// 执行方法<mappers>
  20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  21. </mappers>List brands = brandMapper.selectAll();<mappers>
  22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  23. </mappers>System.out.println(brands);<mappers>
  24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  25. </mappers>// 释放资源<mappers>
  26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  27. </mappers>sqlSession.close();}

  复制代码

5.3 查询

本节要点：

• MyBatis的SQL映射文件中，SQL语句如何接收对应参数
  

• 使用占位符进行参数传递
  
  
  
  • 占位符名称和参数保持一致
    
  • 占位符
    
    
    
    • #{占位符名}：会替换为?，防止SQL注入，一般用于替换字段值
      
    • ${占位符名}：存在SQL注入问题，一般用于执行动态SQL语句，如表名列名不固定的情况（见）
      
    
    
  
  
• 编写接口方法
  1. void update(Brand brand);

  复制代码
• SQL映射文件查询代码标签
  1. <mappers>
  2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  3. </mappers><mappers>
  4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  5. </mappers><mappers>
  6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  7. </mappers>select *<mappers>
  8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  9. </mappers>from tb_brand where id = #{id};

  复制代码
• 测试方法
  1. @Test<mappers>
  2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  3. </mappers>public void testSelectByCondition() throws IOException {<mappers>
  4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  5. </mappers><mappers>
  6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  7. </mappers>// 接收参数<mappers>
  8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  9. </mappers><mappers>
  10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  11. </mappers>int status = 1;<mappers>
  12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  13. </mappers><mappers>
  14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  15. </mappers>String companyName = "华为";<mappers>
  16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  17. </mappers><mappers>
  18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  19. </mappers>String brandName = "华为";<mappers>
  20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  21. </mappers><mappers>
  22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  23. </mappers>// 获取SqlSessionFactory<mappers>
  24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  25. </mappers><mappers>
  26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  27. </mappers>String resource = "mybatis-config.xml";<mappers>
  28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  29. </mappers><mappers>
  30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  31. </mappers>InputStream inputStream = Resources.getResourceAsStream(resource);<mappers>
  32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  33. </mappers><mappers>
  34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  35. </mappers>SqlSessionFactory sqlSessionFactory =<mappers>
  36.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  37. </mappers><mappers>
  38.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  39. </mappers><mappers>
  40.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  41. </mappers> new SqlSessionFactoryBuilder().build(inputStream);<mappers>
  42.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  43. </mappers><mappers>
  44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  45. </mappers>// 获取sqlSession对象<mappers>
  46.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  47. </mappers><mappers>
  48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  49. </mappers>SqlSession sqlSession = sqlSessionFactory.openSession();<mappers>
  50.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  51. </mappers><mappers>
  52.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  53. </mappers>// 获取mapper接口的代理对象<mappers>
  54.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  55. </mappers><mappers>
  56.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  57. </mappers>BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);<mappers>
  58.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  59. </mappers><mappers>
  60.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  61. </mappers>// 执行方法<mappers>
  62.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  63. </mappers><mappers>
  64.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  65. </mappers>companyName = "%" + companyName + "%";<mappers>
  66.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  67. </mappers><mappers>
  68.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  69. </mappers>brandName = "%" + brandName + "%";<mappers>
  70.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  71. </mappers><mappers>
  72.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  73. </mappers>List brands = brandMapper.selectByCondition(status, companyName, brandName);<mappers>
  74.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  75. </mappers><mappers>
  76.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  77. </mappers>System.out.println(brands);<mappers>
  78.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  79. </mappers><mappers>
  80.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  81. </mappers>// 释放资源<mappers>
  82.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  83. </mappers><mappers>
  84.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  85. </mappers>sqlSession.close();<mappers>
  86.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
  87. </mappers>}

  复制代码

5.4 多条件查询

本节要点：

• 多条件查询：如果有多个参数，需要使用@Paran("SQL参数占位符名称")注解
  
• 多条件的动态条件查询：对象属性名称要和参数占位符名称一致
  （详见5-2解决数据库字段和实体类字段名不同的问题）
  
• 单条件的动态条件查询：保证key要和参数占位符名称一致
  

• 多条件查询
  
  
  
  • SQL映射文件
    1. <mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers><mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers><mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>select *<mappers>
    8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    9. </mappers>from tb_brand<mappers>
    10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    11. </mappers>where status = #{status}<mappers>
    12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    13. </mappers>and company_name like #{companyName}<mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers>and brand_name like #{brandName}

    复制代码
  • 散装参数
    
    
    
    • 接口
      1. // 散装参数List selectByCondition(<mappers>
      2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      3. </mappers>@Param("status")int status,<mappers>
      4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      5. </mappers> @Param("companyName")String companyName,<mappers>
      6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      7. </mappers> @Param("brandName")String brandName);

      复制代码
    • 测试方法
      1. @Test<mappers>
      2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      3. </mappers>public void testSelectByCondition() throws IOException {<mappers>
      4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      5. </mappers><mappers>
      6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      7. </mappers>// 接收参数<mappers>
      8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      9. </mappers><mappers>
      10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      11. </mappers>int status = 1;<mappers>
      12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      13. </mappers><mappers>
      14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      15. </mappers>String companyName = "华为";<mappers>
      16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      17. </mappers><mappers>
      18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      19. </mappers>String brandName = "华为";<mappers>
      20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      21. </mappers><mappers>
      22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      23. </mappers>// 获取SqlSessionFactory<mappers>
      24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      25. </mappers><mappers>
      26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      27. </mappers>String resource = "mybatis-config.xml";<mappers>
      28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      29. </mappers><mappers>
      30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      31. </mappers>InputStream inputStream = Resources.getResourceAsStream(resource);<mappers>
      32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      33. </mappers><mappers>
      34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      35. </mappers>SqlSessionFactory sqlSessionFactory =<mappers>
      36.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      37. </mappers><mappers>
      38.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      39. </mappers><mappers>
      40.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      41. </mappers>new SqlSessionFactoryBuilder().build(inputStream);<mappers>
      42.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      43. </mappers><mappers>
      44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      45. </mappers>// 获取sqlSession对象<mappers>
      46.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      47. </mappers><mappers>
      48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      49. </mappers>SqlSession sqlSession = sqlSessionFactory.openSession();<mappers>
      50.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      51. </mappers><mappers>
      52.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      53. </mappers>// 获取mapper接口的代理对象<mappers>
      54.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      55. </mappers><mappers>
      56.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      57. </mappers>BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);<mappers>
      58.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      59. </mappers><mappers>
      60.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      61. </mappers>// 执行方法<mappers>
      62.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      63. </mappers><mappers>
      64.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      65. </mappers>companyName = "%" + companyName + "%";<mappers>
      66.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      67. </mappers><mappers>
      68.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      69. </mappers>brandName = "%" + brandName + "%";<mappers>
      70.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      71. </mappers><mappers>
      72.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      73. </mappers>List brands = brandMapper.selectByCondition(<mappers>
      74.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      75. </mappers><mappers>
      76.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      77. </mappers><mappers>
      78.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      79. </mappers>status, companyName, brandName);<mappers>
      80.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      81. </mappers><mappers>
      82.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      83. </mappers>System.out.println(brands);<mappers>
      84.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      85. </mappers><mappers>
      86.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      87. </mappers>// 释放资源<mappers>
      88.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      89. </mappers><mappers>
      90.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      91. </mappers>sqlSession.close();<mappers>
      92.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
      93. </mappers>}

      复制代码
    
    
  • 对象参数
    
    
    
    • 接口
      1. // 对象参数
      2. List<Brand> selectByCondition(Brand brand);

      复制代码
    • 测试方法
      1. // 细节不表，仅展示执行方法
      2. // 执行方法
      3. Brand brand = new Brand();
      4. brand.setStatus(status);
      5. brand.setCompanyName("%" + companyName + "%");
      6. brand.setBrandName("%" + brandName + "%");
      7. List<Brand> brands = brandMapper.selectByCondition(brand);
      8. System.out.println(brands);

      复制代码
    
    
  • map集合参数
    
    
    
    • 接口
      1. // 集合参数
      2. List<Brand> selectByCondition(Map map);

      复制代码
    • 测试方法
      1. // 细节不表，仅展示执行方法
      2. // 执行方法
      3. Map map = new HashMap();
      4. map.put("status", status);
      5. map.put("companyName", "%" + companyName + "%");
      6. map.put("brandName", "%" + brandName + "%");
      7. List<Brand> brands = brandMapper.selectByCondition(map);
      8. System.out.println(brands);

      复制代码
    
    
  
  
• 多条件动态条件查询
  

  优化条件查询，如页面上表单存在多个条件选项，但实际填写表单仅使用部分条件筛选的情况
  

  
  
  
  
  • SQL映射文件
    1. <mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers><mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers><mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>select *<mappers>
    8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    9. </mappers>from tb_brand<mappers>
    10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    11. </mappers><mappers>
    12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    13. </mappers><mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers><mappers>
    16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    17. </mappers><mappers>
    18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    19. </mappers><mappers>
    20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    21. </mappers>status = #{status}<mappers>
    22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    23. </mappers><mappers>
    24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    25. </mappers><mappers>
    26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    27. </mappers><mappers>
    28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    29. </mappers><mappers>
    30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    31. </mappers><mappers>
    32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    33. </mappers><mappers>
    34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    35. </mappers>and company_name like #{companyName}<mappers>
    36.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    37. </mappers><mappers>
    38.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    39. </mappers><mappers>
    40.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    41. </mappers><mappers>
    42.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    43. </mappers><mappers>
    44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    45. </mappers><mappers>
    46.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    47. </mappers><mappers>
    48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    49. </mappers>and brand_name like #{brandName}<mappers>
    50.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    51. </mappers><mappers>
    52.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    53. </mappers><mappers>
    54.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    55. </mappers>

    复制代码

    注：
    

    
    
    • if标签的test属性中可以包含逻辑或等逻辑判断，使用and、or进行连接
      
    • 若条件SQL中同时包含AND等连接符
      
      
      
      • 对所有的条件前都加AND，并在WHERE后加任意真判断，即WHERE 1=1 AND ... AND ...
        
      • 加入判断标签造轮子，自行决定添加AND的条件
        
      • 使用标签替换原SQL中的WHERE关键字，MyBatis将自动进行语法修正，如示例所示
        
      
      

    
    
  
  
• 单条件的动态条件查询
  

  优化条件查询：如表单中存在多个条件筛选，但仅有其中一个生效的情况
  

  
  
  • 使用标签
    
    
    
    • choose标签类似于Java中的switch
      
    • when标签类似于Java中的case
      
    • otherwise标签类似于Java中的default
      
    
    

  
  
  
  
  • SQL映射文件
    1. <mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers><mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers><mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>select *<mappers>
    8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    9. </mappers>from tb_brand<mappers>
    10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    11. </mappers><mappers>
    12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    13. </mappers><mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers><mappers>
    16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    17. </mappers><mappers>
    18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    19. </mappers><mappers>
    20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    21. </mappers><mappers>
    22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    23. </mappers><mappers>
    24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    25. </mappers><mappers>
    26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    27. </mappers><mappers>
    28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    29. </mappers>status = #{status}<mappers>
    30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    31. </mappers><mappers>
    32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    33. </mappers><mappers>
    34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    35. </mappers><mappers>
    36.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    37. </mappers><mappers>
    38.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    39. </mappers><mappers>
    40.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    41. </mappers><mappers>
    42.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    43. </mappers><mappers>
    44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    45. </mappers><mappers>
    46.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    47. </mappers><mappers>
    48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    49. </mappers>company_name like #{companyName}<mappers>
    50.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    51. </mappers><mappers>
    52.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    53. </mappers><mappers>
    54.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    55. </mappers><mappers>
    56.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    57. </mappers><mappers>
    58.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    59. </mappers><mappers>
    60.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    61. </mappers><mappers>
    62.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    63. </mappers><mappers>
    64.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    65. </mappers><mappers>
    66.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    67. </mappers><mappers>
    68.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    69. </mappers>brand_name like #{brandName}<mappers>
    70.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    71. </mappers><mappers>
    72.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    73. </mappers><mappers>
    74.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    75. </mappers><mappers>
    76.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    77. </mappers><mappers>
    78.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    79. </mappers><mappers>
    80.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    81. </mappers>

    复制代码
  
  

5.6 添加数据与MyBatis事务

• 添加
  
  
  
  • 接口
    1. // 添加
    2. void add(Brand brand);

    复制代码
  • SQL映射文件
    1. <mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers>insert into tb_brand (brand_name, company_name, ordered, description, status)<mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers>values (#{brandName}, #{companyName}, #{ordered}, #{description}, #{status});

    复制代码
  • 测试方法
    1. @Testpublic void testAdd() throws IOException {<mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers>// 接收参数<mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers>int status = 1;<mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>String companyName = "aaa";<mappers>
    8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    9. </mappers>String brandName = "xxx";<mappers>
    10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    11. </mappers>String description = "这是一段介绍";<mappers>
    12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    13. </mappers>int ordered = 100;<mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers>// 获取SqlSessionFactory<mappers>
    16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    17. </mappers>String resource = "mybatis-config.xml";<mappers>
    18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    19. </mappers>InputStream inputStream = Resources.getResourceAsStream(resource);<mappers>
    20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    21. </mappers>SqlSessionFactory sqlSessionFactory =<mappers>
    22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    23. </mappers><mappers>
    24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    25. </mappers> new SqlSessionFactoryBuilder().build(inputStream);<mappers>
    26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    27. </mappers>// 获取sqlSession对象<mappers>
    28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    29. </mappers>// SqlSession sqlSession = sqlSessionFactory.openSession();<mappers>
    30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    31. </mappers>SqlSession sqlSession = sqlSessionFactory.openSession(true);<mappers>
    32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    33. </mappers>// 获取mapper接口的代理对象<mappers>
    34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    35. </mappers>BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);<mappers>
    36.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    37. </mappers>// 执行方法<mappers>
    38.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    39. </mappers>Brand brand = new Brand();<mappers>
    40.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    41. </mappers>brand.setStatus(1);<mappers>
    42.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    43. </mappers>brand.setBrandName(brandName);<mappers>
    44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    45. </mappers>brand.setCompanyName(companyName);<mappers>
    46.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    47. </mappers>brand.setDescription(description);<mappers>
    48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    49. </mappers>brand.setOrdered(ordered);<mappers>
    50.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    51. </mappers>brandMapper.add(brand);<mappers>
    52.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    53. </mappers>System.out.println("添加成功");<mappers>
    54.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    55. </mappers>// 提交事务<mappers>
    56.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    57. </mappers>// sqlSession.commit();<mappers>
    58.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    59. </mappers>// 释放资源<mappers>
    60.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    61. </mappers>sqlSession.close();}

    复制代码
  
  
• Mybatis事务
  

  MyBatis默认手动事务，执行添加等操作时会自动回滚
  

  
  
  
  
  • MyBayis事务处理的方法
    1. // 方法一：在获取sqlSession对象时设置参数，开启自动事务
    2. SqlSession sqlSession = sqlSessionFactory.openSession(true);
    3. sqlSession.close();
    4. // 方法二：手动提交事务
    5. SqlSession sqlSession = sqlSessionFactory.openSession();
    6. sqlSession.commit();
    7. sqlSession.close();

    复制代码
  
  
• 添加 - 主键返回
  

  传入实体类对象进行数据添加，在数据添加完成后，会将id信息写回该实体类对象
  

  
  
  
  
  • SQL映射文件
    1. <mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers>insert into tb_brand (brand_name, company_name, ordered, description, status)<mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers>values (#{brandName}, #{companyName}, #{ordered}, #{description}, #{status});

    复制代码
  • 获取写回信息
    1. Integer id = brand.getId();

    复制代码
  
  

5.7 修改

• 修改整条数据
  
  
  
  • 接口
    1. // 修改，可使用int返回值，返回受影响行数
    2. void update(Brand brand);

    复制代码
  • SQL映射文件
    1. <mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers>update tb_brand<mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers>set brand_name = #{brandName},<mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>set company_name = #{companyName},<mappers>
    8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    9. </mappers>set ordered = #{ordered},<mappers>
    10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    11. </mappers>set description = #{description},<mappers>
    12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    13. </mappers>set status = #{status}<mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers>where id = #{id};

    复制代码
  
  
• 修改部分字段
  

  优化上述代码应对仅修改部分属性导致其他属性数据丢失问题
  使用标签替换set关键字列表，区别于标签，注意语法
  

  
  
  
  
  • SQL映射文件
    1. <mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers>update tb_brand<mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers><mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers><mappers>
    8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    9. </mappers><mappers>
    10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    11. </mappers><mappers>
    12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    13. </mappers><mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers>brand_name = #{brandName},<mappers>
    16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    17. </mappers><mappers>
    18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    19. </mappers><mappers>
    20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    21. </mappers><mappers>
    22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    23. </mappers><mappers>
    24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    25. </mappers><mappers>
    26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    27. </mappers><mappers>
    28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    29. </mappers>company_name = #{companyName},<mappers>
    30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    31. </mappers><mappers>
    32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    33. </mappers><mappers>
    34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    35. </mappers><mappers>
    36.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    37. </mappers><mappers>
    38.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    39. </mappers><mappers>
    40.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    41. </mappers><mappers>
    42.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    43. </mappers>ordered = #{ordered},<mappers>
    44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    45. </mappers><mappers>
    46.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    47. </mappers><mappers>
    48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    49. </mappers><mappers>
    50.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    51. </mappers><mappers>
    52.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    53. </mappers><mappers>
    54.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    55. </mappers><mappers>
    56.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    57. </mappers>description = #{description},<mappers>
    58.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    59. </mappers><mappers>
    60.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    61. </mappers><mappers>
    62.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    63. </mappers><mappers>
    64.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    65. </mappers><mappers>
    66.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    67. </mappers><mappers>
    68.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    69. </mappers><mappers>
    70.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    71. </mappers>status = #{status},<mappers>
    72.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    73. </mappers><mappers>
    74.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    75. </mappers><mappers>
    76.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    77. </mappers><mappers>
    78.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    79. </mappers>where id = #{id};

    复制代码
  • 测试代码
    1. @Testpublic void testUpdate() throws IOException {<mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers>// 接收参数<mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers>int id = 5;<mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>int status = 0;<mappers>
    8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    9. </mappers>String companyName = "AAA";<mappers>
    10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    11. </mappers>String brandName = "XXX";<mappers>
    12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    13. </mappers>int ordered = 300;<mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers>// 获取SqlSessionFactory<mappers>
    16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    17. </mappers>String resource = "mybatis-config.xml";<mappers>
    18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    19. </mappers>InputStream inputStream = Resources.getResourceAsStream(resource);<mappers>
    20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    21. </mappers>SqlSessionFactory sqlSessionFactory =<mappers>
    22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    23. </mappers><mappers>
    24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    25. </mappers> new SqlSessionFactoryBuilder().build(inputStream);<mappers>
    26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    27. </mappers>// 获取sqlSession对象<mappers>
    28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    29. </mappers>SqlSession sqlSession = sqlSessionFactory.openSession(true);<mappers>
    30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    31. </mappers>// 获取mapper接口的代理对象<mappers>
    32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    33. </mappers>BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);<mappers>
    34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    35. </mappers>// 执行方法<mappers>
    36.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    37. </mappers>Brand brand = new Brand();<mappers>
    38.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    39. </mappers>brand.setId(id);<mappers>
    40.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    41. </mappers>brand.setStatus(status);<mappers>
    42.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    43. </mappers>brand.setBrandName(brandName);<mappers>
    44.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    45. </mappers>brand.setCompanyName(companyName);<mappers>
    46.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    47. </mappers>brand.setOrdered(ordered);<mappers>
    48.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    49. </mappers>brandMapper.update(brand);<mappers>
    50.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    51. </mappers>System.out.println("修改成功");<mappers>
    52.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    53. </mappers>// 释放资源<mappers>
    54.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    55. </mappers>sqlSession.close();}

    复制代码
  
  

5.8 删除数据

• 删除一条数据
  
  
  
  • 接口
    1. // 删除一条数据
    2. void deleteById(int id);

    复制代码
  • SQL映射文件
    1. <mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers>delete<mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers>from tb_brand<mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>where id = #{id};

    复制代码
  • 测试
    1. @Testpublic void testDeleteById() throws IOException {<mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers>// 接收参数<mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers>int id = 5;<mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>// 获取SqlSessionFactory<mappers>
    8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    9. </mappers>String resource = "mybatis-config.xml";<mappers>
    10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    11. </mappers>InputStream inputStream = Resources.getResourceAsStream(resource);<mappers>
    12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    13. </mappers>SqlSessionFactory sqlSessionFactory =<mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers><mappers>
    16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    17. </mappers> new SqlSessionFactoryBuilder().build(inputStream);<mappers>
    18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    19. </mappers>// 获取sqlSession对象<mappers>
    20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    21. </mappers>SqlSession sqlSession = sqlSessionFactory.openSession(true);<mappers>
    22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    23. </mappers>// 获取mapper接口的代理对象<mappers>
    24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    25. </mappers>BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);<mappers>
    26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    27. </mappers>// 执行方法<mappers>
    28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    29. </mappers>brandMapper.deleteById(id);<mappers>
    30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    31. </mappers>System.out.println("删除成功");<mappers>
    32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    33. </mappers>// 释放资源<mappers>
    34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    35. </mappers>sqlSession.close();}

    复制代码
  
  
• 批量删除数据
  

  用于解决删除时传入参数为数组的情况
  

  
  
  • 使用标签代替SQL语句中的id in (?, ?, ..., ?)
    
    
    
    • collection属性为MyBatis封装后数组对应的key，封装后属性值应为array（见注释）
      
      
      
      • MyBatis默认会将数组参数封装为Map集合，其key为array，即 array = ids
        
      • 可在接口中对参数数组使用@Param注解，将封装后的key手动命名，则可在映射文件中使用
        
      
      
    • separator属性为分隔符
      
    • open和close属性分别为在前后拼接字符，主要用于代码规范，示例中未展示
      
    
    

  
  
  
  
  • 接口
    1. // 删除多个数据
    2. void deleteByIds(@Param("ids")int[] ids);

    复制代码
  • SQL映射文件
    1. <mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers>delete<mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers>from tb_brand<mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>where id<mappers>
    8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    9. </mappers>in (<mappers>
    10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    11. </mappers><mappers>
    12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    13. </mappers><mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers><mappers>
    16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    17. </mappers>#{id}<mappers>
    18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    19. </mappers><mappers>
    20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    21. </mappers>);

    复制代码
  • 测试
    1. @Testpublic void testDeleteByIds() throws IOException {<mappers>
    2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    3. </mappers>// 接收参数<mappers>
    4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    5. </mappers>int[] ids = {6, 7};<mappers>
    6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    7. </mappers>// 获取SqlSessionFactory<mappers>
    8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    9. </mappers>String resource = "mybatis-config.xml";<mappers>
    10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    11. </mappers>InputStream inputStream = Resources.getResourceAsStream(resource);<mappers>
    12.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    13. </mappers>SqlSessionFactory sqlSessionFactory =<mappers>
    14.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    15. </mappers><mappers>
    16.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    17. </mappers> new SqlSessionFactoryBuilder().build(inputStream);<mappers>
    18.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    19. </mappers>// 获取sqlSession对象<mappers>
    20.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    21. </mappers>SqlSession sqlSession = sqlSessionFactory.openSession(true);<mappers>
    22.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    23. </mappers>// 获取mapper接口的代理对象<mappers>
    24.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    25. </mappers>BrandMapper brandMapper = sqlSession.getMapper(BrandMapper.class);<mappers>
    26.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    27. </mappers>// 执行方法<mappers>
    28.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    29. </mappers>brandMapper.deleteByIds(ids);<mappers>
    30.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    31. </mappers>System.out.println("删除成功");<mappers>
    32.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    33. </mappers>// 释放资源<mappers>
    34.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
    35. </mappers>sqlSession.close();}

    复制代码
  
  

5.9 MyBatis参数传递

• 概述
  
• 多个参数
  

  设有如下代码：

  1. User select(@Param("username") String username,@Param("password") String password);

  复制代码

  MyBatis会将散装的多个参数封装为Map集合
  

  
  
  
  
  • 若不使用@Param注解，则会使用以下命名规则：
    1. map.put("arg0"，参数值1);
    2. map.put("arg1"，参数值2);
    3. map.put("param1"，参数值1);
    4. map.put("param2"，参数值2);

    复制代码
    即Map集合中的参数的key分别为arg0, arg1, param1, param2
    
  • 使用@Param注解会将Map集合中的参数的arg替换为指定内容，增强其可读性
    
  
  
• 单个参数
  
  
  
  • POJO类型：直接使用，要求属性名和参数占位符名称一致（见 5.2 SQL映射文件）
    
  • Map集合类型：直接使用，要求key和参数占位符名称一致（见 5.2 SQL映射文件）
    
  • Collection集合类型：封装Map集合，可以使用@Param注解替换Map集合中默认arg键名
    1. map.put("arg0"，collection集合);
    2. map.put("collection"，collection集合;

    复制代码
  • List集合类型：封装为Map集合，可以使用@Param注解，替换Map集合中默认的arg键名
    1. map.put("arg0"，list集合);
    2. map.put("collection"，list集合);
    3. map.put("list"，list集合);

    复制代码
  • Array类型：封装为Map集合，可以使用@Param注解，替换Map集合中默认的arg键名
    1. map.put("arg0"，数组);
    2. map.put("array"，数组);

    复制代码
  • 其他类型：直接使用，与参数占位符无关，但尽量见名知意
    
  
  

6、通过注解实现CRUD

• 概述
  
  
  
  • 用于简化开发，可以对简单的查询使用注解进行操作，以替换xml中的statement
    
  • 对于复杂的查询，仍然建议使用xml配置文件，否则代码会十分混乱
    
  
  
• 使用方法
  
  
  
  • 注解（部分）
    
    
    
    • 查询 ：@Select
      
    • 添加 ：@Insert
      
    • 修改 ：@Update
      
    • 删除 ：@Delete
      
    
    
  • 示例
    
    
    
    • 使用注解简化查询
      

      
      

      
      
      • 原接口
        1. Brand selectById(int id);

        复制代码
      • 原SQL映射文件
        1. <mappers>
        2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
        3. </mappers><mappers>
        4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
        5. </mappers><mappers>
        6.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
        7. </mappers>select *<mappers>
        8.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
        9. </mappers>from tb_brand<mappers>
        10.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
        11. </mappers>where id = #{id};

        复制代码

      
      
      
      
      • 使用注解进行开发
        
        
        
        • 接口
          1. @ResultMap("brandResultMap")                // 解决数据库和实体类字段名称不同
          2. @Select("select * from tb_brand where id = #{id}")        // 查询语句
          3. Brand selectById(int id);

          复制代码
        • SQL映射文件：不再需要原先的statement
          1. <mappers>
          2.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
          3. </mappers><mappers>
          4.     <mapper resource="priv/dandelion/mapper/UserMapper.xml"/>
          5. </mappers>

          复制代码
        
        
      
      
    
    
  
  

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