事務操作的通知

假設您希望同時執行事務操作和一些基本的效能分析通知。如何在 <tx:annotation-driven/> 的上下文中實現這一點？

當您呼叫 updateFoo(Foo) 方法時，您希望看到以下行為：

配置的效能分析切面開始執行。
事務通知執行。
被通知物件上的方法執行。
事務提交。
效能分析切面報告整個事務方法呼叫的確切持續時間。

本章不詳細解釋 AOP（除非與事務相關）。有關 AOP 配置和 AOP 的詳細資訊，請參閱AOP。

以下程式碼顯示了前面討論的簡單效能分析切面：

Java
Kotlin

package x.y;

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;
	}
}

package x.y

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
	}
}

通知的順序由 Ordered 介面控制。有關通知順序的完整詳細資訊，請參閱通知排序。

以下配置建立了一個 fooService Bean，並按期望的順序對其應用了效能分析和事務切面：

<?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>

您可以以類似的方式配置任意數量的附加切面。

以下示例建立了與前兩個示例相同的設定，但使用了純 XML 宣告式方法：

<?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>

上述配置的結果是一個 fooService Bean，按該順序對其應用了效能分析和事務切面。如果您希望效能分析通知在進入時執行在事務通知之後，並在退出時執行在事務通知之前，您可以交換效能分析切面 Bean 的 order 屬性值，使其高於事務通知的 order 值。

您可以以類似的方式配置附加切面。