Spring AOP 方式三 BeanNameAutoProxyCreator

例子

IHello 接口类

package com.benx.mvc;

public interface IHello {

    public void say();
    
}

IHello接口实现类

package com.benx.mvc;


public class HelloImpl implements IHello {

    public void say() {
        System.out.println("Hello World");
    }
    
}

拦截器

package com.benx.mvc;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;


public class HelloInterceptor implements MethodInterceptor {

    public Object invoke(MethodInvocation methodinvocation) throws Throwable {

        System.out.println("start");

        Object ob = methodinvocation.proceed();

        System.out.println("end");

        return ob;
    }

}

spring.xml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" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jee="http://www.springframework.org/schema/jee" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.0.xsd 
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.0.xsd">

    <context:component-scan base-package="com.benx.mvc" />

    <bean id="hello1" class="com.benx.mvc.HelloImpl" />
    
    <bean id="hello2" class="com.benx.mvc.HelloImpl" />
    
    <bean id="helloInterceptor" class="com.benx.mvc.HelloInterceptor" />


    <bean
        class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">
        <property name="beanNames" value="hel*" />
        <property name="interceptorNames">
            <list>
                <value>helloInterceptor</value>
            </list>
        </property>
    </bean>


</beans>

测试类

package com.benx.mvc;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class BeanNameAutoProxyCreatorTest {

    public static void main(String[] args) {

        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("spring.xml");

        IHello hello1 = (IHello) context.getBean("hello1");

        hello1.say();

        IHello hello2 = (IHello) context.getBean("hello1");

        hello2.say();
    }
}

结果：

start
Hello World
end
start
Hello World
end

实现原理：

1、BeanNameAutoProxyCreator父类AbstractAutoProxyCreator 继承接口InstantiationAwareBeanPostProcessor，其方法postProcessBeforeInstantiation 在 Bean实例创建之前使用。

2、Spring在初始化Bean时，优先调用InstantiationAwareBeanPostProcessor.postProcessBeforeInstantiation,如果该方法不为NULL，那么直接返回该对象。BeanNameAutoProxyCreator就是使用该方式，返回代理对象。

3、创建代理对象，实际也是使用ProxyFactory来返回代理。