读mybatis源码之十四：mybatis事务处理

来源：互联网发布：daxulu域名更换编辑：程序博客网时间：2024/05/02 04:25

1、自身事务处理

public void doxxxxx(){ TransactionFactory transactionFactory = new JdbcTransactionFactory(); userMapper userDao=getSession().getMapper(UserMapper.class); Transaction newTransaction=transactionFactory.newTransaction(getSession().getConnection()); try {  userDao.insert(xxx);  userDao.update(xxx); } catch (Exception e) {  newTransaction.rollback();  e.printStackTrace(); } finally {    newTransaction.close(); }}

可以看出主要是事务连接。

2、与spring集成后，事务处理

BlogMapper mapper = (BlogMapper)app.getBean("blogMapper");    Blog sblog = new Blog();    sblog.setId(2);    sblog.setName("测试加密555");    sblog.setAddr("测试加密--------------123444");    mapper.insertBlogByObj(sblog);

这种数据能够提交上去，为什么呢？看看与spring集成后它的处理方式

首先看如何得到mapper的，通过MapperFactoryBean的getObject（）方法得到

  public T getObject() throws Exception {    return getSqlSession().getMapper(this.mapperInterface);  }

那getSqlSession()又是如何得到的呢？跟踪是通过SqlSessionTemplate得到，SqlSessionTemplate里面是什么呢？

发现是一个sqlSessionProxy代理：

 public SqlSessionTemplate(SqlSessionFactory sqlSessionFactory, ExecutorType executorType,      PersistenceExceptionTranslator exceptionTranslator) {    notNull(sqlSessionFactory, "Property 'sqlSessionFactory' is required");    notNull(executorType, "Property 'executorType' is required");    this.sqlSessionFactory = sqlSessionFactory;    this.executorType = executorType;    this.exceptionTranslator = exceptionTranslator;    this.sqlSessionProxy = (SqlSession) newProxyInstance(        SqlSessionFactory.class.getClassLoader(),        new Class[] { SqlSession.class },        new SqlSessionInterceptor());  }

具体看SqlSessionInterceptor，就可以看出为什么spring集成后，不显示提交，也能自动提交了：

  private class SqlSessionInterceptor implements InvocationHandler {    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {      final SqlSession sqlSession = getSqlSession(          SqlSessionTemplate.this.sqlSessionFactory,          SqlSessionTemplate.this.executorType,          SqlSessionTemplate.this.exceptionTranslator);      try {        Object result = method.invoke(sqlSession, args);        if (!isSqlSessionTransactional(sqlSession, SqlSessionTemplate.this.sqlSessionFactory)) {          // force commit even on non-dirty sessions because some databases require          // a commit/rollback before calling close()          sqlSession.commit(true);        }        return result;      } catch (Throwable t) {        Throwable unwrapped = unwrapThrowable(t);        if (SqlSessionTemplate.this.exceptionTranslator != null && unwrapped instanceof PersistenceException) {          Throwable translated = SqlSessionTemplate.this.exceptionTranslator.translateExceptionIfPossible((PersistenceException) unwrapped);          if (translated != null) {            unwrapped = translated;          }        }        throw unwrapped;      } finally {        closeSqlSession(sqlSession, SqlSessionTemplate.this.sqlSessionFactory);      }    }  }

if (!isSqlSessionTransactional(sqlSession, SqlSessionTemplate.this.sqlSessionFactory)) {

// force commit even on non-dirty sessions because some databases require

// a commit/rollback before calling close()

sqlSession.commit(true);

}

这部分重点，如果配置了事务，就由配置事务处理，没有配置就直接提交，所以这里相当于他帮你提交了。

closeSqlSession里面也是一样，如果有事务，是session释放，如果没有就是session关闭，跟踪下去就是事务关闭，mybatis spring结合后里面SpringManagedTransaction的close，用的DataSourceUtils的releaseConnection

public void close() throws SQLException {

releaseConnection(this.connection, this.dataSource);

}

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