java设置多数据源

三个数据库：master主库、back_one从库1、back_two从库2
1.application.yml设置三个数据库信息

1. spring:
2.   datasource:
3.     driver-class-name : com.mysql.jdbc.Driver
4.     # 主库
5.     master:
6.       jdbcUrl : jdbc:mysql://xxx:3306/master?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&serverTimezone=GMT%2b8&allowMultiQueries=true
7.       username : xxx
8.       password : xxx
9.       name :
10.     # 从库1
11.     slave:
12.       enabled: true  # 从数据源开关/默认关闭
13.       jdbcUrl: jdbc:mysql://xxx:3306/back_one?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true&serverTimezone=GMT%2b8
14.       username: xxx
15.       password: xxx
16.       name :
17.     # 从库2
18.     slave2:
19.       enabled: true  # 从数据源开关/默认关闭
20.       jdbcUrl: jdbc:mysql://xxx:3306/back_two?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&allowMultiQueries=true&serverTimezone=GMT%2b8
21.       username: xxx
22.       password: xxx
23.       name :
24.     druid.maxActive : 150
25.     druid.initialSize : 5
26.     druid.minIdle : 5
27.     druid.maxWait : 60000
28.     druid.filters : stat
29.     druid.timeBetweenEvictionRunsMillis : 60000
30.     druid.minEvictableIdleTimeMillis : 300000
31.     druid.validationQuery : SELECT 1    #多个数据源时配置：select count(*) from dual
32.     druid.testWhileIdle : true
33.     druid.testOnBorrow : false
34.     druid.testOnReturn : false
35.     druid.poolPreparedStatements : false
36.     druid.maxPoolPreparedStatementPerConnectionSize : -1
37.     druid.timeBetweenLogStatsMillis : 0
38.     druid.keep-alive : true
39.     druid.connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000;druid.stat.logSlowSql=true

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注意：
一个数据源时：validationQuery: SELECT 1；
多个数据源时：validationQuery: select count(*) from dual
2.代码

（1）DataSource

1. import java.lang.annotation.*;
3. @Target(ElementType.TYPE)
4. @Retention(RetentionPolicy.RUNTIME)
5. @Documented
6. public @interface DataSource {
8.     DataSourceType value() default DataSourceType.MASTER;
10. }

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（2）DataSourceAspect

1. import org.aspectj.lang.JoinPoint;
2. import org.aspectj.lang.annotation.After;
3. import org.aspectj.lang.annotation.Aspect;
4. import org.aspectj.lang.annotation.Before;
5. import org.aspectj.lang.annotation.Pointcut;
6. import org.aspectj.lang.reflect.MethodSignature;
7. import org.springframework.core.annotation.Order;
8. import org.springframework.stereotype.Component;
10. import java.lang.reflect.Method;
13. @Aspect
14. @Order(1)
15. @Component
16. public class DataSourceAspect {
18.     @Pointcut("execution(public * com.xxx.mapper..*.*(..))")
19.     public void pointcut() {}
21.     @Before("pointcut()")
22.     public void doBefore(JoinPoint joinPoint)
23.     {
24.         Method method = ((MethodSignature)joinPoint.getSignature()).getMethod();
25.         DataSource dataSource = method.getAnnotation(DataSource.class);  //获取方法上的注解
26.         if(dataSource == null){
27.             Class<?> clazz= joinPoint.getTarget().getClass().getInterfaces()[0];
28.             dataSource =clazz.getAnnotation(DataSource.class);  //获取类上面的注解
29.             if(dataSource == null) return;
30.         }
31.         if (dataSource != null) {
32.             DynamicDataSourceContextHolder.setDataSourceType(dataSource.value().name());
33.         }
34.     }
36.     @After("pointcut()")
37.     public void after(JoinPoint point) {
38.         //清理掉当前设置的数据源，让默认的数据源不受影响
39.         DynamicDataSourceContextHolder.clearDataSourceType();
40.     }
41. }

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（3）DataSourceConfig

1. import com.alibaba.druid.pool.DruidDataSource;
2. import org.springframework.beans.factory.annotation.Value;
3. import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
4. import org.springframework.context.annotation.Bean;
5. import org.springframework.context.annotation.Configuration;
6. import org.springframework.context.annotation.DependsOn;
7. import org.springframework.context.annotation.Primary;
9. import javax.sql.DataSource;
10. import java.sql.SQLException;
11. import java.util.HashMap;
12. import java.util.Map;
14. @Configuration
15. public class DataSourceConfig {
17.     //主数据源
18.     @Value("${spring.datasource.master.jdbcUrl}")
19.     private String masterJdbcUrl;
20.     @Value("${spring.datasource.master.username}")
21.     private String masterUsername;
22.     @Value("${spring.datasource.master.password}")
23.     private String masterPassword;
24.     @Value("${spring.datasource.driver-class-name}")
25.     private String masterDriverClassName;
26.     @Value("${spring.datasource.master.name}")
27.     private String name;
28.     //从数据源1
29.     @Value("${spring.datasource.slave.jdbcUrl}")
30.     private String slaveJdbcUrl1;
31.     @Value("${spring.datasource.slave.username}")
32.     private String slaveUsername1;
33.     @Value("${spring.datasource.slave.password}")
34.     private String slavePassword1;
35.     @Value("${spring.datasource.driver-class-name}")
36.     private String slaveDriverClassName1;
37.     @Value("${spring.datasource.slave.name}")
38.     private String slaveName;
39.     //从数据源2
40.     @Value("${spring.datasource.slave2.jdbcUrl}")
41.     private String slaveJdbcUrl2;
42.     @Value("${spring.datasource.slave2.username}")
43.     private String slaveUsername2;
44.     @Value("${spring.datasource.slave2.password}")
45.     private String slavePassword2;
46.     @Value("${spring.datasource.driver-class-name}")
47.     private String slaveDriverClassName2;
48.     @Value("${spring.datasource.slave2.name}")
49.     private String slaveName2;
50.     //其他相关配置
51.     @Value("${spring.datasource.druid.initialSize}")
52.     private int initialSize;
53.     @Value("${spring.datasource.druid.minIdle}")
54.     private int minIdle;
55.     @Value("${spring.datasource.druid.maxWait}")
56.     private int maxWait;
57.     @Value("${spring.datasource.druid.filters}")
58.     private String filters;
59.     @Value("${spring.datasource.druid.timeBetweenEvictionRunsMillis}")
60.     private int timeBetweenEvictionRunsMillis;
61.     @Value("${spring.datasource.druid.minEvictableIdleTimeMillis}")
62.     private int minEvictableIdleTimeMillis;
63.     @Value("${spring.datasource.druid.validationQuery}")
64.     private String validationQuery;
65.     @Value("${spring.datasource.druid.testWhileIdle}")
66.     private boolean testWhileIdle;
67.     @Value("${spring.datasource.druid.testOnBorrow}")
68.     private boolean testOnBorrow;
69.     @Value("${spring.datasource.druid.testOnReturn}")
70.     private boolean testOnReturn;
71.     @Value("${spring.datasource.druid.poolPreparedStatements}")
72.     private boolean poolPreparedStatements;
73.     @Value("${spring.datasource.druid.maxPoolPreparedStatementPerConnectionSize}")
74.     private int maxPoolPreparedStatementPerConnectionSize;
75.     @Value("${spring.datasource.druid.timeBetweenLogStatsMillis}")
76.     private int timeBetweenLogStatsMillis;
77.     @Value("${spring.datasource.druid.keep-alive}")
78.     private boolean keepAlive;
79.     @Value("${spring.datasource.druid.connectionProperties}")
80.     private String connectionProperties;
83.     @Bean
84.     public DataSource masterDataSource() {
85.         return generateDataSource(masterJdbcUrl,masterUsername,masterPassword,masterDriverClassName,name);
86.     }
88.     @Bean
89.     @ConditionalOnProperty(prefix = "spring.datasource.slave", name = "enabled", havingValue = "true")
90.     public DataSource slaveDataSource1() {
91.         return generateDataSource(slaveJdbcUrl1,slaveUsername1,slavePassword1,slaveDriverClassName1,slaveName);
92.     }
94.     @Bean
95.     @ConditionalOnProperty(prefix = "spring.datasource.slave2", name = "enabled", havingValue = "true")
96.     public DataSource slaveDataSource2() {
97.         return generateDataSource(slaveJdbcUrl2,slaveUsername2,slavePassword2,slaveDriverClassName2,slaveName2);
98.     }
101.     private DruidDataSource generateDataSource(String url,String username,String password,String driverClassName,String name){
102.         DruidDataSource datasource = new DruidDataSource();
103.         datasource.setUrl(url);
104.         datasource.setUsername(username);
105.         datasource.setPassword(password);
106.         datasource.setDriverClassName(driverClassName);
107.         datasource.setName(name);
108.         datasource.setInitialSize(initialSize);
109.         datasource.setMinIdle(minIdle);
110.         datasource.setMaxWait(maxWait);
111.         datasource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);
112.         datasource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);
113.         datasource.setValidationQuery(validationQuery);
114.         datasource.setTestWhileIdle(testWhileIdle);
115.         datasource.setTestOnBorrow(testOnBorrow);
116.         datasource.setTestOnReturn(testOnReturn);
117.         datasource.setPoolPreparedStatements(poolPreparedStatements);
118.         datasource.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize);
119.         datasource.setKeepAlive(keepAlive);
120.         try {
121.             datasource.setFilters(filters);
122.         } catch (SQLException e) {
123.             System.err.println("druid configuration initialization filter: " + e);
124.         }
125.         datasource.setConnectionProperties(connectionProperties);
126.         datasource.setTimeBetweenLogStatsMillis(timeBetweenLogStatsMillis);
127.         return datasource;
128.     }
130.     @Bean(name = "dynamicDataSource")
131.     @DependsOn({"masterDataSource", "slaveDataSource1", "slaveDataSource2"})  //如果不加这个，会报错：The dependencies of some of the beans in the application context form a cycle
132.     @Primary
133.     public DynamicDataSource dataSource(DataSource masterDataSource, DataSource slaveDataSource1, DataSource slaveDataSource2) {
134.         Map<Object, Object> targetDataSources = new HashMap<>();
135.         targetDataSources.put(DataSourceType.MASTER.name(), masterDataSource);
136.         targetDataSources.put(DataSourceType.BACKONE.name(), slaveDataSource1);
137.         targetDataSources.put(DataSourceType.BACKTWO.name(), slaveDataSource2);
138.         return new DynamicDataSource(masterDataSource, targetDataSources);
139.     }
141. }

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（4）DataSourceType

1. public enum DataSourceType {
2.     /**
3.      * 主库
4.      */
5.     MASTER,
7.     /**
8.      * 从库1
9.      */
10.     BACKONE,
12.     /**
13.      * 从库2
14.      */
15.     BACKTWO;
16. }

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（5）DynamicDataSource

1. import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
3. import javax.sql.DataSource;
4. import java.util.Map;
6. public class DynamicDataSource extends AbstractRoutingDataSource {
8.     public DynamicDataSource(DataSource defaultTargetDataSource, Map<Object, Object> targetDataSources) {
9.         super.setDefaultTargetDataSource(defaultTargetDataSource);
10.         super.setTargetDataSources(targetDataSources);
11.         // afterPropertiesSet()方法调用时用来将targetDataSources的属性写入resolvedDataSources中的
12.         super.afterPropertiesSet();
13.     }
15.     /**
16.      * 根据Key获取数据源的信息
17.      */
18.     @Override
19.     protected Object determineCurrentLookupKey() {
20.         return DynamicDataSourceContextHolder.getDataSourceType();
21.     }
23. }

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（6）DynamicDataSourceContextHolder

1. import org.slf4j.Logger;
2. import org.slf4j.LoggerFactory;
4. public class DynamicDataSourceContextHolder {
5.     public static final Logger log = LoggerFactory.getLogger(DynamicDataSourceContextHolder.class);
7.     /**
8.      * 使用ThreadLocal维护变量，ThreadLocal为每个使用该变量的线程提供独立的变量副本，
9.      *  所以每一个线程都可以独立地改变自己的副本，而不会影响其它线程所对应的副本。
10.      */
11.     private static final ThreadLocal<String> CONTEXT_HOLDER = new ThreadLocal<>();
13.     /**
14.      * 设置数据源变量
15.      */
16.     public static void setDataSourceType(String dataSourceType){
17.         log.info("切换到{}数据源", dataSourceType);
18.         CONTEXT_HOLDER.set(dataSourceType);
19.     }
21.     /**
22.      * 获取数据源变量
23.      */
24.     public static String getDataSourceType(){
25.         return CONTEXT_HOLDER.get();
26.     }
28.     /**
29.      * 清空数据源变量
30.      */
31.     public static void clearDataSourceType(){
32.         CONTEXT_HOLDER.remove();
33.     }
35. }

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3.使用

（1）调用从库1

1. /**
2. * 调用从库1
3. */
4. @Component
5. @DataSource(value = DataSourceType.BACKONE)
6. public interface TestOneMapper {
8. }

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（2）调用从库2

1. /**
2. * 调用从库2
3. */
4. @Component
5. @DataSource(value = DataSourceType.BACKTWO)
6. public interface TestTwoMapper {
8. }

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