Advising Transactional Operations

假设你想要运行事务操作和一些基本分析建议。如何在 <tx:annotation-driven/> 上下文中执行此操作？

Suppose you want to run both transactional operations and some basic profiling advice. How do you effect this in the context of <tx:annotation-driven/>?

当你调用 updateFoo(Foo) 方法时，你希望看到以下操作：

When you invoke the updateFoo(Foo) method, you want to see the following actions:

The configured profiling aspect starts.
The transactional advice runs.
The method on the advised object runs.
The transaction commits.
The profiling aspect reports the exact duration of the whole transactional method invocation.

本章不打算非常详细地解释 AOP（除了它如何应用于事务）。请参阅 AOP 详细了解 AOP 配置和 AOP 常识。

This chapter is not concerned with explaining AOP in any great detail (except as it applies to transactions). See AOP for detailed coverage of the AOP configuration and AOP in general.

以下代码展示了前面讨论的简单剖析切面：

The following code shows the simple profiling aspect discussed earlier:

Java
Kotlin

import org.aspectj.lang.ProceedingJoinPoint;
import org.springframework.util.StopWatch;
import org.springframework.core.Ordered;

public class SimpleProfiler implements Ordered {

	private int order;

	// allows us to control the ordering of advice
	public int getOrder() {
		return this.order;
	}

	public void setOrder(int order) {
		this.order = order;
	}

	// this method is the around advice
	public Object profile(ProceedingJoinPoint call) throws Throwable {
		Object returnValue;
		StopWatch clock = new StopWatch(getClass().getName());
		try {
			clock.start(call.toShortString());
			returnValue = call.proceed();
		} finally {
			clock.stop();
			System.out.println(clock.prettyPrint());
		}
		return returnValue;
	}
}

import org.aspectj.lang.ProceedingJoinPoint
import org.springframework.util.StopWatch
import org.springframework.core.Ordered

class SimpleProfiler : Ordered {

	private var order: Int = 0

	// allows us to control the ordering of advice
	override fun getOrder(): Int {
		return this.order
	}

	fun setOrder(order: Int) {
		this.order = order
	}

	// this method is the around advice
	fun profile(call: ProceedingJoinPoint): Any {
		var returnValue: Any
		val clock = StopWatch(javaClass.name)
		try {
			clock.start(call.toShortString())
			returnValue = call.proceed()
		} finally {
			clock.stop()
			println(clock.prettyPrint())
		}
		return returnValue
	}
}

建议的顺序通过 Ordered 接口进行控制。有关建议顺序的全部详细信息，请参见 Advice ordering。

The ordering of advice is controlled through the Ordered interface. For full details on advice ordering, see Advice ordering.

以下配置创建了一个 fooService Bean，其中按所需顺序对其应用了分析和事务切面：

The following configuration creates a fooService bean that has profiling and transactional aspects applied to it in the desired order:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans
		https://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/tx
		https://www.springframework.org/schema/tx/spring-tx.xsd
		http://www.springframework.org/schema/aop
		https://www.springframework.org/schema/aop/spring-aop.xsd">

	<bean id="fooService" class="x.y.service.DefaultFooService"/>

	<!-- this is the aspect -->
	<bean id="profiler" class="x.y.SimpleProfiler">
		<!-- run before the transactional advice (hence the lower order number) -->
		<property name="order" value="1"/>
	</bean>

	<tx:annotation-driven transaction-manager="txManager" order="200"/>

	<aop:config>
			<!-- this advice runs around the transactional advice -->
			<aop:aspect id="profilingAspect" ref="profiler">
				<aop:pointcut id="serviceMethodWithReturnValue"
						expression="execution(!void x.y..*Service.*(..))"/>
				<aop:around method="profile" pointcut-ref="serviceMethodWithReturnValue"/>
			</aop:aspect>
	</aop:config>

	<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
		<property name="driverClassName" value="oracle.jdbc.driver.OracleDriver"/>
		<property name="url" value="jdbc:oracle:thin:@rj-t42:1521:elvis"/>
		<property name="username" value="scott"/>
		<property name="password" value="tiger"/>
	</bean>

	<bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
		<property name="dataSource" ref="dataSource"/>
	</bean>

</beans>

你可以以类似的方式配置任意数量的其他切面。

You can configure any number of additional aspects in similar fashion.

以下示例创建与前两个示例相同的设置，但使用纯 XML 声明方式：

The following example creates the same setup as the previous two examples but uses the purely XML declarative approach:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans
		https://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/tx
		https://www.springframework.org/schema/tx/spring-tx.xsd
		http://www.springframework.org/schema/aop
		https://www.springframework.org/schema/aop/spring-aop.xsd">

	<bean id="fooService" class="x.y.service.DefaultFooService"/>

	<!-- the profiling advice -->
	<bean id="profiler" class="x.y.SimpleProfiler">
		<!-- run before the transactional advice (hence the lower order number) -->
		<property name="order" value="1"/>
	</bean>

	<aop:config>
		<aop:pointcut id="entryPointMethod" expression="execution(* x.y..*Service.*(..))"/>
		<!-- runs after the profiling advice (cf. the order attribute) -->

		<aop:advisor advice-ref="txAdvice" pointcut-ref="entryPointMethod" order="2"/>
		<!-- order value is higher than the profiling aspect -->

		<aop:aspect id="profilingAspect" ref="profiler">
			<aop:pointcut id="serviceMethodWithReturnValue"
					expression="execution(!void x.y..*Service.*(..))"/>
			<aop:around method="profile" pointcut-ref="serviceMethodWithReturnValue"/>
		</aop:aspect>

	</aop:config>

	<tx:advice id="txAdvice" transaction-manager="txManager">
		<tx:attributes>
			<tx:method name="get*" read-only="true"/>
			<tx:method name="*"/>
		</tx:attributes>
	</tx:advice>

	<!-- other <bean/> definitions such as a DataSource and a TransactionManager here -->

</beans>

先前配置的结果是 fooService bean，根据顺序对其应用了性能分析和事务切面。如果您希望性能分析通知在进入时在事务通知之后运行，在退出时在事务通知之前运行，您可以交换性能分析切面 bean 的 order 属性的值，使其高于事务通知的 order 值。

The result of the preceding configuration is a fooService bean that has profiling and transactional aspects applied to it in that order. If you want the profiling advice to run after the transactional advice on the way in and before the transactional advice on the way out, you can swap the value of the profiling aspect bean’s order property so that it is higher than the transactional advice’s order value.

您可以以类似方式配置其他切面。

You can configure additional aspects in similar fashion.