事务传播的几种类型

参考代码文件：

spring-tx-4.2.0.RELEASE.jar

org.springframework.transaction.TransactionDefinition

• (1) PROPAGATION_REQUIRED

  Support a current transaction; create a new one if none exists. This is typically the default setting of a transaction definition, and typically defines a transaction synchronization scope.

  如果当前没有事务，就新建一个事务，如果已经存在一个事务中，加入到这个事务中。这是最常见的选择。

• (2) PROPAGATION_SUPPORTS

  Support a current transaction; execute non-transactionally if none exists.

  支持当前事务，如果当前没有事务，就以非事务方式执行。

• (3) PROPAGATION_MANDATORY

  Support a current transaction; throw an exception if no current transaction exists.

  使用当前的事务，如果当前没有事务，就抛出异常。

• (4) PROPAGATION_REQUIRES_NEW

  Create a new transaction, suspending the current transaction if one exists.

  新建事务，如果当前存在事务，把当前事务挂起。

• (5) PROPAGATION_NOT_SUPPORTED

  Do not support a current transaction; rather always execute non-transactionally.

  以非事务方式执行操作，如果当前存在事务，就把当前事务挂起。

• (6) PROPAGATION_NEVER

  Do not support a current transaction; throw an exception if a current transaction exists.

  以非事务方式执行，如果当前存在事务，则抛出异常。

• (7) PROPAGATION_NESTED

  Execute within a nested transaction if a current transaction exists, behave like PROPAGATION_REQUIRED else.

  NOTE: Actual creation of a nested transaction will only work on specific transaction managers. Out of the box, this only applies to the JDBC org.springframework.jdbc.datasource.DataSourceTransactionManager when working on a JDBC 3.0 driver. Some JTA providers might support nested transactions as well.

  如果当前存在事务，则在嵌套事务内执行。如果当前没有事务，则执行与PROPAGATION_REQUIRED类似的操作。

  当使用PROPAGATION_NESTED时，底层的数据源必须基于JDBC 3.0，并且实现者需要支持保存点事务机制。