Spring事务传播行为和隔离级别

最新推荐文章于 2024-05-05 22:40:51 发布

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本文详细解析了Java中Spring框架事务管理的七种传播行为，包括REQUIRED、SUPPORTS等，并介绍了五种不同的事务隔离级别及其应用场景。

事务的七种传播行为

看下Transactional注解中Propagation的七种事务的源码

@Transactional(propagation = Propagation.REQUIRED)

public enum Propagation {
	/**
	 * 支持当前事务，如果不存在，则创建一个新事务。
	 * 其子方法必须运行在一个事务中，如果当前存在事务，会加入到存在的事务中，成为一个整体。
	 * Support a current transaction, create a new one if none exists.
	 * Analogous to EJB transaction attribute of the same name.
	 * <p>This is the default setting of a transaction annotation.
	 * 在使用REQUIRED时，当其中一个方法报错，会将整个行为回滚;
	 * 例如需要修改数据库表表数据，只要出现错误，其会全部失败，数据库数据也会回滚;
	 */
	REQUIRED(TransactionDefinition.PROPAGATION_REQUIRED),
	/**
	 * 支持当前事务，如果不存在，以非事务方式执行。
	 * 当最外围事存在是会继承外围事务，如果没有事务，将以非事务的方式运行
	 * Support a current transaction, execute non-transactionally if none exists.
	 * Analogous to EJB transaction attribute of the same name.
	 * <p>Note: For transaction managers with transaction synchronization,
	 * {@code SUPPORTS} is slightly different from no transaction at all,
	 * as it defines a transaction scope that synchronization will apply for.
	 * As a consequence, the same resources (JDBC Connection, Hibernate Session, etc)
	 * will be shared for the entire specified scope. Note that this depends on
	 * the actual synchronization configuration of the transaction manager.
	 * @see org.springframework.transaction.support.AbstractPlatformTransactionManager#setTransactionSynchronization
	 */
	SUPPORTS(TransactionDefinition.PROPAGATION_SUPPORTS),

	/**
	 * 该传播属性强制必须存在一个事务，如果不存在，则抛出异常
	 * Support a current transaction, throw an exception if none exists.
	 * Analogous to EJB transaction attribute of the same name.
	 */
	MANDATORY(TransactionDefinition.PROPAGATION_MANDATORY),

	/**
	 * Create a new transaction, and suspend the current transaction if one exists.
	 * Analogous to the EJB transaction attribute of the same name.
	 * <p><b>NOTE:</b> Actual transaction suspension will not work out-of-the-box
	 * on all transaction managers. This in particular applies to
	 * {@link org.springframework.transaction.jta.JtaTransactionManager},
	 * which requires the {@code javax.transaction.TransactionManager} to be
	 * made available to it (which is server-specific in standard Java EE).
	 * @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager
	 */
	REQUIRES_NEW(TransactionDefinition.PROPAGATION_REQUIRES_NEW),

	/**
	 * 如果当前有事务，则挂起该事务，并且自己创建一个新的事务给自己使用;
     * 如果当前没有事务，则同 REQUIRED
	 * 
	 * Execute non-transactionally, suspend the current transaction if one exists.
	 * Analogous to EJB transaction attribute of the same name.
	 * <p><b>NOTE:</b> Actual transaction suspension will not work out-of-the-box
	 * on all transaction managers. This in particular applies to
	 * {@link org.springframework.transaction.jta.JtaTransactionManager},
	 * which requires the {@code javax.transaction.TransactionManager} to be
	 * made available to it (which is server-specific in standard Java EE).
	 * @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager
	 */
	NOT_SUPPORTED(TransactionDefinition.PROPAGATION_NOT_SUPPORTED),

	/**
	 * 如果当前有事务存在，则抛出异常
	 * Execute non-transactionally, throw an exception if a transaction exists.
	 * Analogous to EJB transaction attribute of the same name.
	 */
	NEVER(TransactionDefinition.PROPAGATION_NEVER),

	/**
	 * 如果当前有事务，则开启子事务（嵌套事务），嵌套事务是独立提交或者回滚;
     * 如果当前没有事务，则同 REQUIRED。
	 * Execute within a nested transaction if a current transaction exists,
	 * behave like {@code REQUIRED} otherwise. There is no analogous feature in EJB.
	 * <p>Note: Actual creation of a nested transaction will only work on specific
	 * transaction managers. Out of the box, this only applies to the JDBC
	 * DataSourceTransactionManager. Some JTA providers might support nested
	 * transactions as well.
	 * @see org.springframework.jdbc.datasource.DataSourceTransactionManager
	 */
	NESTED(TransactionDefinition.PROPAGATION_NESTED);