spring aop 上的进一步代理

先说下spring aop的普通切面的配置.

首先是maven需要依赖下面这些jar包

<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-core</artifactId>
			<version>4.1.6.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-web</artifactId>
			<version>4.1.6.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-aop</artifactId>
			<version>4.1.6.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-beans</artifactId>
			<version>4.1.6.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>4.1.6.RELEASE</version>
		</dependency>
		<dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aspects</artifactId>
            <version>3.0.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>1.6.11</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.6.11</version>
        </dependency>
        <dependency>
            <groupId>cglib</groupId>
            <artifactId>cglib</artifactId>
            <version>2.1_3</version>
        </dependency>

其次是建立普通的接口和类,名字我是随便起的

package com.demo.aop.test;

public interface UserService {

	void insert();
}


package com.demo.aop.test.impl;

import org.springframework.stereotype.Service;

import com.demo.aop.test.UserService;

@Service
public class UserServiceImpl implements UserService {

	@Override
	public void insert() {
		System.out.println("userServiceImpl insert");
	}

}

然后是建立切面类，目前只添加了前置方法

package com.demo.aop.test;

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.stereotype.Component;

@Component
@Aspect
public class UserAspect {

	@Before("execution(void com.demo.aop.test.impl ..* .*(..))")
	public void before() {
		System.out.println("UserAspect insert");
	}
}

最后是spring配置文件的配置

<?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" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:jpa="http://www.springframework.org/schema/data/jpa" xmlns:util="http://www.springframework.org/schema/util" 
	xsi:schemaLocation="
  http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
  http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
  http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
  http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
  http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd">


   <!-- 自动扫描的包 -->
   <context:component-scan base-package="com.demo.aop.test"></context:component-scan>
   
   <!-- 配置启动代理 -->
   <aop:aspectj-autoproxy proxy-target-class="true"></aop:aspectj-autoproxy>

</beans>

最后就是测试方法了

package com.demo.aop.test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {

	public static void main(String[] args) {
		
		ApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
		
		UserService userService = context.getBean(UserService.class);
		
		userService.insert();
		
		
	}
}

执行后如果看到下面这两行，说明配置成功了

前置通知被执行了，还有本来的方法也被执行了，如果你失败的话那可以看看我的另一篇文章，里面是具体的操作步骤，这里就不显示说了

http://blog.youkuaiyun.com/zxc_user/article/details/77856086

下面才是这篇文章要讲的东西，就是如果你想在类上面动态添加方法,如果修改原来的逻辑很复杂，那可以通过下面的方式进行为其代理类加上新的方法

首先，创建你新方法的接口和基本实现类

package com.demo.aop.test;

public interface OtherMethod {

	void method();
}

package com.demo.aop.test.impl;

import com.demo.aop.test.OtherMethod;

public class OtherMethodImpl implements OtherMethod{

	@Override
	public void method() {
		System.out.println("i am other method");
	}

}

然后，新增一个类，如下

package com.demo.aop.test;

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.DeclareParents;
import org.springframework.stereotype.Component;

import com.demo.aop.test.impl.OtherMethodImpl;

@Component
@Aspect
public class ParentAspect {

	// value 把当前的类注入到哪些代理类里面. + 号代表包括子类, defaultImpl 该接口的默认实现
	@DeclareParents(value = "com.demo.aop.test.impl.UserServiceImpl+", defaultImpl = OtherMethodImpl.class)
	public OtherMethod otherMethod;
}

然后是调用了

package com.demo.aop.test;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {

	public static void main(String[] args) {
		
		ApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
		
		UserService userService = context.getBean(UserService.class);
		
		userService.insert();
		
		//把 userService 强转为 OtherMethod,就可以获得他的方法了
		OtherMethod otherMethod = (OtherMethod) userService;
		
		otherMethod.method();
	}
}

如果你看到下面的情况,那就表示代理上的代理已经成功了

至于为什么要用接口，道理很简单，就是你这个OtherMethod 的实现类以后可能会要修改,容易替换点