如何使用Spring自动代理创建器?
Spring 自动代理创建器
前言:
在经典的spring Aop中,可以手工为目标Bean创建代理Bean,配置文件必须为每一个需要增强的Bean声明一个代理,结果配置文件里声明了大量的代理Bean。
在经典的Spring Aop中,Spring提供了自动代理创建器(Aotu proxy creator),有了自动代理创建器,就不再需要使用ProxyFactoryBean手工地创建代理了。
接口Animal和Book:
package com.zzj.aop; public interface Animal { public void eat(); public void drink(); }
package com.zzj.aop; public interface Book { public void read(); }
目标类:
package com.zzj.aop; public class Human implements Animal, Book{ @Override public void eat() { System.out.println("eat..."); } @Override public void drink() { System.out.println("drink..."); } @Override public void read() { System.out.println("read..."); } }
前置通知和后置通知:
package com.zzj.aop; import java.lang.reflect.Method; import org.springframework.aop.MethodBeforeAdvice; public class MethodBefore implements MethodBeforeAdvice { public void before(Method arg0, Object[] arg1, Object arg2) throws Throwable { System.out.println("before " + arg0.getName()); } }
package com.zzj.aop; import java.lang.reflect.Method; import org.springframework.aop.AfterReturningAdvice; public class MethodAfter implements AfterReturningAdvice { public void afterReturning(Object arg0, Method arg1, Object[] arg2, Object arg3) throws Throwable { System.out.println( "after " + arg1.getName()); } }
Spring配置文件:
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <!-- 定义目标对象 --> <bean id="human" class="com.zzj.aop.Human"></bean> <!-- 定义通知 --> <bean id="beforeAdvice" class="com.zzj.aop.MethodBefore"></bean> <bean id="afterAdvice" class="com.zzj.aop.MethodAfter"></bean> <!-- 定义切入点 --> <bean id="methodNamePointcut" class="org.springframework.aop.support.NameMatchMethodPointcut"> <property name="mappedNames"> <list> <value>eat</value> <value>read</value> </list> </property> </bean> <!-- 定义后置增强器(关联通知和切入点) --> <bean id="AfterMethodNameAdvisor" class="org.springframework.aop.support.DefaultPointcutAdvisor"> <property name="advice" ref="afterAdvice"></property> <property name="pointcut" ref="methodNamePointcut"></property> </bean> <!-- 定义前置增强器(关联通知和切入点) --> <bean id="BeforeMethodNameAdvisor" class="org.springframework.aop.aspectj.AspectJExpressionPointcutAdvisor"> <property name="advice" ref="beforeAdvice"></property> <property name="expression"> <value>execution(* *.*in*(..))</value><!-- 可匹配drink --> </property> </bean> <!-- 定义自动代理创建器 --> <bean class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator"> <property name="beanNames"> <list> <value>*human</value> </list> </property> <property name="interceptorNames"> <list> <value>AfterMethodNameAdvisor</value> <value>BeforeMethodNameAdvisor</value> </list> </property> </bean> </beans>
以上自动代理器可以为以human结尾的Bean创建代理。
测试:
package com.zzj.aop; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Test { /** * @param args */ public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext( "applicationContext.xml"); Animal animal = (Animal) context.getBean("human"); Book book = (Book) animal; animal.eat(); animal.drink(); book.read(); } }
输出:
eat... after eat before drink drink... read... after read
Spring还提供了另一个自动代理创建器:DefaultAdvisorAutoProxyCreator。这个自动代理创建器不需要任何配置,他会自动检查Ioc容器里声明的每一个增强器和Bean。如果存在与增强器切入点匹配的的Bean,那么DefaultAdvisorAutoProxyCreator将自动为其创建代理。
<bean class="org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator"/>
需要注意的是,DefaultAdvisorAutoProxyCreator可能会代理那些不希望被代理的目标Bean,所以使用时要格外小心。
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