Spring 7大事务传播模型
REQUIRED /** * 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. */ 必须有一个事务，如果当前已存在则用当前的，如果不存在则新建一个事务 SUPPORTS /** * 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, * PROPAGATION_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 */ 使用当前事物，如果当前则以无事务模式运行 MANDATORY /** * Support a current transaction, throw an exception if none exists. * Analogous to EJB transaction attribute of the same name. */ 表示强制需要一个事务，如果不存事务则抛出异常 REQUIRES_NEW /** * 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 it to it (which is server-specific in standard Java EE). * @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager */ 每次都创建一个新的事务，如果当前存在事务则挂起当前事务运行新事务，两个事务互相独立，新事物回滚也不会影响外部事务 NOT_SUPPORTED /** * 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 it to it (which is server-specific in standard Java EE). * @see org.springframework.transaction.jta.JtaTransactionManager#setTransactionManager */ 已非事务模式运行，如果当前存在事务则挂起当前事务 NEVER /** * Execute non-transactionally, throw an exception if a transaction exists. * Analogous to EJB transaction attribute of the same name. */ 从不需要事务，如果当前存在事务则抛出异常，刚好与 MANDATORY 相反 NESTED /** * Execute within a nested transaction if a current transaction exists, * behave like PROPAGATION_REQUIRED else. 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 when working on a JDBC 3.0 driver. * Some JTA providers might support nested transactions as well. * @see org.springframework.jdbc.datasource.DataSourceTransactionManager */ 嵌入式事务模式，与PROPAGATION_REQUIRED相似，如果没有就新建，如果有适用当前事务，但是NESTED具体当前事务多个保存点，可以部分回滚。仅适用于JDBC事务管理，内部可以独立回滚并且不影响外部。
