Spring 声明事务中transactionAttributes属性 + - Exception 实现逻辑

下面是一段典型的Spring 声明事务的配置：

	
		
			
		
		
			
		
		
			
				PROPAGATION_REQUIRED
				PROPAGATION_REQUIRED,readOnly
				PROPAGATION_REQUIRED,-ApplicationException,+BusinessException
			
		
	

在Spring声明事务中，我们可以自定义方法的哪些Exception需要回滚，哪些Exception可以直接提交。

通过下面的配置：

PROPAGATION_REQUIRED,-ApplicationException,+BusinessException

- 表示抛出该异常时需要回滚

+表示即使抛出该异常事务同样要提交

-ApplicationException ：表示抛出ApplicationException 时，事务需要回滚。但不是说只抛出ApplicationException 异常时，事务才回滚，如果程序抛出RuntimeException和Error时，事务一样会回滚，即使这里没有配置。因为Spring中默认对所有的RuntimeException和Error都会回滚事务。

Spring中是如何实现这段逻辑的：

调用的是

org.springframework.transaction.interceptor.RuleBasedTransactionAttribute.rollbackOn(Throwable ex)

public boolean rollbackOn(Throwable ex) {
		if (logger.isTraceEnabled()) {
			logger.trace("Applying rules to determine whether transaction should rollback on " + ex);
		}

		RollbackRuleAttribute winner = null;
		int deepest = Integer.MAX_VALUE;

		//配置文件中的回滚异常列表，当然去掉了-，只有name，commit的规则是另外一个对象
		if (this.rollbackRules != null) {
			for (RollbackRuleAttribute rule : this.rollbackRules) {
				//使用抛出exception的className(全路径className)进行indexOf match
				//如果没有match上会继续搜索superClass name进行match，到Throwable class为止
				int depth = rule.getDepth(ex);
				if (depth >= 0 && depth < deepest) {
					deepest = depth;
					winner = rule;
				}
			}
		}

		if (logger.isTraceEnabled()) {
			logger.trace("Winning rollback rule is: " + winner);
		}

		// User superclass behavior (rollback on unchecked) if no rule matches.
		if (winner == null) {
			logger.trace("No relevant rollback rule found: applying default rules");
			//如果没有match上，调用此方法继续match，判断instance of RuntimeException or Error
			return super.rollbackOn(ex);
		}

		return !(winner instanceof NoRollbackRuleAttribute);
	}

rule.getDepth方法代码

        因为使用的是className的全路径进行indexOf匹配，所以如果自定义异常是：com.abc.ApplicationException，你在xml配置文件中定义为：-abc，同样会match上，事务也会回滚，这一点需要注意。

       另外一点，如何在xml中定义的是-Exception，这样只要class的全路径中包含Exception字段，如包名，也会匹配上。

        public int getDepth(Throwable ex) {
		return getDepth(ex.getClass(), 0);
	}


	private int getDepth(Class exceptionClass, int depth) {
		if (exceptionClass.getName().indexOf(this.exceptionName) != -1) {
			// Found it!
			return depth;
		}
		// If we've gone as far as we can go and haven't found it...
		if (exceptionClass.equals(Throwable.class)) {
			return -1;
		}
		return getDepth(exceptionClass.getSuperclass(), depth + 1);
	}

super.rollbackOn(Throwable ex ) 方法代码

很简单的一行代码，这就是为什么RuntimeException和Error也会回滚啦。

	public boolean rollbackOn(Throwable ex) {
 		return (ex instanceof RuntimeException || ex instanceof Error);
 	}

几次测试输出的debug日志：

[08/24 03:35:39] [DEBUG] RuleBasedTransactionAttribute: Applying rules to determine whether transaction should rollback on usertest.exception.BusinessException: Error
[08/24 03:35:39] [DEBUG] RuleBasedTransactionAttribute: Winning rollback rule is: RollbackRuleAttribute with pattern [BusinessException]
[08/24 03:35:39] [DEBUG] DataSourceTransactionManager: Triggering beforeCompletion synchronization
[08/24 03:35:39] [DEBUG] DataSourceTransactionManager: Initiating transaction rollback
[08/24 03:35:39] [DEBUG] DataSourceTransactionManager: Rolling back JDBC transaction on Connection [org.apache.commons.dbcp.PoolableConnection@1db05b2]
[08/24 03:35:39] [DEBUG] DataSourceTransactionManager: Triggering afterCompletion synchronization
[08/24 03:35:39] [DEBUG] TransactionSynchronizationManager: Clearing transaction synchronization
[08/24 03:35:39] [DEBUG] TransactionSynchronizationManager: Removed value [org.springframework.jdbc.datasource.ConnectionHolder@1833eca] for key [org.apache.commons.dbcp.BasicDataSource@4aa0ce] from thread [main]
[08/24 03:35:39] [DEBUG] DataSourceTransactionManager: Releasing JDBC Connection [org.apache.commons.dbcp.PoolableConnection@1db05b2] after transaction
[08/24 03:35:39] [DEBUG] DataSourceUtils: Returning JDBC Connection to DataSource




[08/24 03:39:16] [DEBUG] TransactionInterceptor: Completing transaction for [usertest.dao.UsersDAO.testInsertAndUpdate] after exception: java.lang.Exception: Error
[08/24 03:39:16] [DEBUG] RuleBasedTransactionAttribute: Applying rules to determine whether transaction should rollback on java.lang.Exception: Error
[08/24 03:39:16] [DEBUG] RuleBasedTransactionAttribute: Winning rollback rule is: null
[08/24 03:39:16] [DEBUG] RuleBasedTransactionAttribute: No relevant rollback rule found: applying superclass default
[08/24 03:39:16] [DEBUG] DataSourceTransactionManager: Triggering beforeCommit synchronization
[08/24 03:39:16] [DEBUG] DataSourceTransactionManager: Triggering beforeCompletion synchronization
[08/24 03:39:16] [DEBUG] DataSourceTransactionManager: Initiating transaction commit
[08/24 03:39:16] [DEBUG] DataSourceTransactionManager: Committing JDBC transaction on Connection [org.apache.commons.dbcp.PoolableConnection@1db05b2]
[08/24 03:39:16] [DEBUG] DataSourceTransactionManager: Triggering afterCommit synchronization


[08/24 03:41:40] [DEBUG] TransactionInterceptor: Completing transaction for [usertest.dao.UsersDAO.testInsertAndUpdate] after exception: usertest.exception.BusinessException: Error
[08/24 03:41:40] [DEBUG] RuleBasedTransactionAttribute: Applying rules to determine whether transaction should rollback on usertest.exception.BusinessException: Error
[08/24 03:41:40] [DEBUG] RuleBasedTransactionAttribute: Winning rollback rule is: RollbackRuleAttribute with pattern [Exception]
[08/24 03:41:40] [DEBUG] DataSourceTransactionManager: Triggering beforeCompletion synchronization
[08/24 03:41:40] [DEBUG] DataSourceTransactionManager: Initiating transaction rollback
[08/24 03:41:40] [DEBUG] DataSourceTransactionManager: Rolling back JDBC transaction on Connection [org.apache.commons.dbcp.PoolableConnection@1db05b2]
[08/24 03:41:40] [DEBUG] DataSourceTransactionManager: Triggering afterCompletion synchronization
[08/24 03:41:40] [DEBUG] TransactionSynchronizationManager: Clearing transaction synchronization