ibatis中Transaction有四个实现类
其中spring的SqlMapClientFactoryBean类中
private Class transactionConfigClass = ExternalTransactionConfig.class;
public SqlMapClientFactoryBean() { this.transactionConfigProperties = new Properties(); this.transactionConfigProperties.setProperty("SetAutoCommitAllowed", "false");}
1.ExternalTransaction
不指定事务类型时，默认使用此类型的事务；
在调用getConnection()时才去建立数据库连接；
AutoCommit默认为true；
commit()和rollback()均为空实现；
public ExternalTransaction(DataSource ds, boolean defaultAutoCommit, boolean setAutoCommitAllowed, int isolationLevel) throws TransactionException { this.dataSource = ds; if (this.dataSource == null) { throw new TransactionException("ExternalTransaction initialization failed. DataSource was null."); } else { this.defaultAutoCommit = defaultAutoCommit; this.setAutoCommitAllowed = setAutoCommitAllowed; this.isolationLevel.setIsolationLevel(isolationLevel); }}
public Connection getConnection() throws SQLException, TransactionException { if (this.connection == null) { this.init(); } return this.connection;}
private void init() throws SQLException, TransactionException { this.connection = this.dataSource.getConnection(); if (this.connection == null) { throw new TransactionException("ExternalTransaction could not start transaction. Cause: The DataSource returned a null connection."); } else { this.isolationLevel.applyIsolationLevel(this.connection); if (this.setAutoCommitAllowed && this.connection.getAutoCommit() != this.defaultAutoCommit) { this.connection.setAutoCommit(this.defaultAutoCommit); } if (connectionLog.isDebugEnabled()) { this.connection = ConnectionLogProxy.newInstance(this.connection); } }}
2.JdbcTransaction
- 需要在配置文件中指定transactionConfigClass为此类型；
- 在调用getConnection()时才去建立数据库连接，同上；
- AutoCommit默认为false；
- 由TransactionManager统一管理，在执行过程中自动调用commit()和rollback()提交或者回滚；
<bean id="sqlMapClient" class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">
<property name="configLocation" value="classpath:sql-map-config.xml">
<property name="dataSource" ref="dataSource">
<property name="transactionConfigClass" value="com.ibatis.sqlmap.engine.transaction.jdbc.JdbcTransactionConfig">
public void commit() throws SQLException, TransactionException { if (this.connection != null) { this.connection.commit(); }}public void rollback() throws SQLException, TransactionException { if (this.connection != null) { this.connection.rollback(); }}
3.JtaTransaction
Todo:暂时还未看到，待补充。。。。。。。。。。。。。。。
4.UserProviderTransaction
- 不能在配置文件中指定此类型的事务，需要先有Connection的情况下才可以使用此类型，即：在TransactionManager的begin()方法中不会new出此类型的事务；
- AutoCommit为之前获取的Connection设置的值，默认为true；
- commit()和rollback()没有发现哪里使用；
- 在使用spring的SqlMapClientTemplate操作时，会根据获取到的SpringCon组装一个UserProviderTransaction,此时配置文件中设置的上述三种事务类型均失效；
个人理解：
如果外层不手动配置事务，此事务的作用仅仅是提供了一个connection而已,此时connection.getAutoCommit()==true,并没有真正起到事务的作用；
如果外层配置了事务，此事务跟外层配置的事务使用同一个connection,外层事务会设置connection的Autocommit=false，真正起作用的还是外层的事务。
public UserProvidedTransaction(Connection connection) { if (connectionLog.isDebugEnabled()) { this.connection = ConnectionLogProxy.newInstance(connection); } else { this.connection = connection; }}
public Connection getConnection() throws SQLException, TransactionException { return this.connection;}参考流程：
当外部配置事务时，开启事务时会先获取一个connection
DataSourceTransactionManager.javasqlMapClientTemplate获取连接时
