tx命名空間下提供了什么元素？

tx命名空間包括了如下三個元素定義：

tx:advice

Defines the transactional semantics of the AOP advice that is to be executed.

tx:annotation-driven

Indicates that transaction configuration is defined by Java 5 annotations on bean classes.

tx:jta-transaction-manager

Creates a default JtaTransactionManager bean with name "transactionManager", matching the default bean name expected by the "annotation-driven" tag。