第四章 通知Bean

1.创建经典的Spring切面

定义业务类

public interface Performer {void perform();}

public class Stevie implements Performer {public void perform() {System.out.println("Stevie showing");}}

定义一个观众类Audience

public class Audience {public void takeSeats(){//找到自己的座位(表演之前执行)System.out.println("The audience is taking their seats.");}public void turnOffCellPhones(){//关闭自己手机(表演之前执行)System.out.println("The audience is turning off their cellphones");}public void applaud(){//鼓掌(成功演出之后执行)System.out.println("CLAP CLAP CLAP CLAP CLAP");}public void demandRedund(){//要求退票(演出失败之后执行,出现异常)System.out.println("Boo! We want our money back!");}}

创建通知（前通知，后通知以及抛出后通知）AudienceAdvice

public class AudienceAdvice implements MethodBeforeAdvice,AfterReturningAdvice, ThrowsAdvice {//实现三种通知类型private Audience audience;public void setAudience(Audience audience) {this.audience = audience;}public void before(Method method, Object[] args, Object target)throws Throwable {// 方法之前调用audience.takeSeats();audience.turnOffCellPhones();}public void afterReturning(Object returnValue, Method method,Object[] args, Object target) throws Throwable {// 成功返回之后执行audience.applaud();}public void afterThrowing(Throwable throwable) {// 抛出异常之后执行audience.demandRedund();}}

定义AspectJ切点以及使用ProxyFactoryBean配置XML

    <bean id="stevieTarget" class="com.springinaction.chapter04.classicAOP.Stevie"/>    <bean id="audience" class="com.springinaction.chapter04.classicAOP.Audience"/>    <bean id="audienceAdvice" class="com.springinaction.chapter04.classicAOP.AudienceAdvice">    <property name="audience" ref="audience"/>    </bean>           <bean id="adienceAdvisor" class="org.springframework.aop.aspectj.AspectJExpressionPointcutAdvisor"><property name="advice" ref="audienceAdvice"/><property name="expression" value="execution(* *.perform(..))"/></bean><bean id="audienceProxyBase" class="org.springframework.aop.framework.ProxyFactoryBean" abstract="true"><property name="proxyInterfaces" value="com.springinaction.chapter04.Performer"/><property name="interceptorNames" value="adienceAdvisor"/></bean><bean id="stevie" parent="audienceProxyBase"><property name="target" ref="stevieTarget"/></bean>

junit测试：

@Testpublic void property(){Performer performer = (Performer) act.getBean("stevie");performer.perform();}

控制台输出：

The audience is taking their seats.
The audience is turning off their cellphones
Stevie showing
CLAP CLAP CLAP CLAP CLAP

2.自动代理

根据上述程序代码，修改其配置XML实现自动代理：

    <bean id="audience" class="com.springinaction.chapter04.classicAOP.Audience"/>    <bean id="audienceAdvice" class="com.springinaction.chapter04.classicAOP.AudienceAdvice">    <property name="audience" ref="audience"/>    </bean>           <bean id="adienceAdvisor" class="org.springframework.aop.aspectj.AspectJExpressionPointcutAdvisor"><property name="advice" ref="audienceAdvice"/><property name="expression" value="execution(* *.perform(..))"/></bean><bean class="org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator"/><bean id="stevie" class="com.springinaction.chapter04.classicAOP.Stevie"/>

3.定义纯粹的POJO切面

在XML文件中引入aop命名空间

<?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"xsi:schemaLocation="http://www.springframework.org/schema/beans           http://www.springframework.org/schema/beans/spring-beans-3.1.xsd           http://www.springframework.org/schema/aop              http://www.springframework.org/schema/aop/spring-aop-3.0.xsd"></beans>    

利用aop命名空间定义切面：

<bean id="audience" class="com.springinaction.chapter04.classicAOP.Audience"/><aop:config><aop:aspect ref="audience"><aop:pointcut id="performance" expression="execution(* *.perform(..))"/><aop:before method="takeSeats" pointcut-ref="performance"/><aop:before method="turnOffCellPhones" pointcut-ref="performance"/><aop:after-returning method="applaud" pointcut-ref="performance"/><aop:after-throwing method="demandRedund" pointcut-ref="performance"/></aop:aspect></aop:config><bean id="stevie" class="com.springinaction.chapter04.classicAOP.Stevie"/>