mybatis SelectKey解析 - ToB企服应用市场:ToB评测及商务社交产业平台

#mapper
int insert(UserDO userDO);
#mapper.xml
<insert id="insert">
<selectKey keyProperty="userId" keyColumn="user_id" order="AFTER" resultType="integer">
select last_insert_id()
</selectKey>
insert into user(username, password, nickname)
values(#{username}, #{password}, #{nickname})
</insert>
#java测试代码
public class Test {
public static void main(String[] args) throws IOException {
try (InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml")) {
// 构建session工厂 DefaultSqlSessionFactory
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
UserDO userDO = new UserDO();
userDO.setUsername("monian");
userDO.setPassword("123");
userDO.setNickname("monianx");
userMapper.insert(userDO);
System.out.println("自增主键userId:" + userDO.getUserId());
}
}
}

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public class PreparedStatementHandler extends BaseStatementHandler {
public PreparedStatementHandler(Executor executor, MappedStatement mappedStatement, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) {
super(executor, mappedStatement, parameter, rowBounds, resultHandler, boundSql);
}
@Override
public int update(Statement statement) throws SQLException {
PreparedStatement ps = (PreparedStatement) statement;
ps.execute();
int rows = ps.getUpdateCount();
Object parameterObject = boundSql.getParameterObject();
KeyGenerator keyGenerator = mappedStatement.getKeyGenerator();
keyGenerator.processAfter(executor, mappedStatement, ps, parameterObject);
return rows;
}
}

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public class SelectKeyGenerator implements KeyGenerator {
public static final String SELECT_KEY_SUFFIX = "!selectKey";
private final boolean executeBefore;
private final MappedStatement keyStatement;
public SelectKeyGenerator(MappedStatement keyStatement, boolean executeBefore) {
// 主sql前面执行还是后面执行
this.executeBefore = executeBefore;
this.keyStatement = keyStatement;
}
@Override
public void processBefore(Executor executor, MappedStatement ms, Statement stmt, Object parameter) {
if (executeBefore) {
processGeneratedKeys(executor, ms, parameter);
}
}
@Override
public void processAfter(Executor executor, MappedStatement ms, Statement stmt, Object parameter) {
if (!executeBefore) {
processGeneratedKeys(executor, ms, parameter);
}
}
// 处理生成的键
private void processGeneratedKeys(Executor executor, MappedStatement ms, Object parameter) {
try {
if (parameter != null && keyStatement != null && keyStatement.getKeyProperties() != null) {
// 获取需要设置的属性值如id
String[] keyProperties = keyStatement.getKeyProperties();
final Configuration configuration = ms.getConfiguration();
final MetaObject metaParam = configuration.newMetaObject(parameter);
// Do not close keyExecutor.
// The transaction will be closed by parent executor.
Executor keyExecutor = configuration.newExecutor(executor.getTransaction(), ExecutorType.SIMPLE);
// 查询sql如 select last_insert_id()获取主键id
List<Object> values = keyExecutor.query(keyStatement, parameter, RowBounds.DEFAULT, Executor.NO_RESULT_HANDLER);
if (values.size() == 0) {
throw new ExecutorException("SelectKey returned no data.");
} else if (values.size() > 1) {
throw new ExecutorException("SelectKey returned more than one value.");
} else {
MetaObject metaResult = configuration.newMetaObject(values.get(0));
// 将主键id的值设置到parameter参数中
if (keyProperties.length == 1) {
if (metaResult.hasGetter(keyProperties[0])) {
setValue(metaParam, keyProperties[0], metaResult.getValue(keyProperties[0]));
} else {
// no getter for the property - maybe just a single value object
// so try that
setValue(metaParam, keyProperties[0], values.get(0));
}
} else {
// 若查询的属性有多个则分别设置
handleMultipleProperties(keyProperties, metaParam, metaResult);
}
}
}
} catch (ExecutorException e) {
throw e;
} catch (Exception e) {
throw new ExecutorException("Error selecting key or setting result to parameter object. Cause: " + e, e);
}
}
private void handleMultipleProperties(String[] keyProperties,
MetaObject metaParam, MetaObject metaResult) {
String[] keyColumns = keyStatement.getKeyColumns();
if (keyColumns == null || keyColumns.length == 0) {
// no key columns specified, just use the property names
for (String keyProperty : keyProperties) {
setValue(metaParam, keyProperty, metaResult.getValue(keyProperty));
}
} else {
if (keyColumns.length != keyProperties.length) {
throw new ExecutorException("If SelectKey has key columns, the number must match the number of key properties.");
}
for (int i = 0; i < keyProperties.length; i++) {
setValue(metaParam, keyProperties[i], metaResult.getValue(keyColumns[i]));
}
}
}
private void setValue(MetaObject metaParam, String property, Object value) {
if (metaParam.hasSetter(property)) {
metaParam.setValue(property, value);
} else {
throw new ExecutorException("No setter found for the keyProperty '" + property + "' in " + metaParam.getOriginalObject().getClass().getName() + ".");
}
}
}

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#mapper
void batchInsert(@Param("userDOList") List<UserDO> userDOList);
#mapper.xml
insert into user(username, password, nickname)
values
<foreach collection="userDOList" item="userDO" separator=",">
(#{userDO.username}, #{userDO.password}, #{userDO.nickname})
</foreach>
</insert>
#java测试代码
public class Test {
public static void main(String[] args) throws IOException {
try (InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml")) {
// 构建session工厂 DefaultSqlSessionFactory
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
UserDO userDO = new UserDO();
userDO.setUsername("monian");
userDO.setPassword("123");
userDO.setNickname("monianx");
UserDO userDO1 = new UserDO();
userDO1.setUsername("monian");
userDO1.setPassword("123");
userDO1.setNickname("monianx");
userMapper.batchInsert(Arrays.asList(userDO, userDO1));
System.out.println("自增主键userId:" + Arrays.asList(userDO.getUserId(), userDO1.getUserId()));
}
}
}

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