spring的aop解讀

之前講過動態代理，其實我們spring比較重要的是IOC和AOP 而IOC的底層原理是反射，AOP的底層實現原理就是動態代理

    spring實現aop的方式有兩種

     第一種：           

   

package com.asiainfo.spring;

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;

/**
 * 切面類（給主要的功能添加額外的功能）
 */
@Aspect
public class AspectDemo {
	/*
         *前置通知，只在方法之前執行
         *第一個*表示所有的返回對象
         *第二個*表示包中所有的類
         *第三個*表示以add開頭的所有方
         *第四個..表示方法中的所有參數
         * /
@Before("execution(* com.asiainfo.spring.*.add*(..))")public void before(){System.out.println("before");}}

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:context="http://www.springframework.org/schema/context"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
        
        <bean id="hello" class="com.asiainfo.spring.HelloBean"></bean>
        <bean id="aspect" class="com.asiainfo.spring.AspectDemo"></bean>
        <aop:aspectj-autoproxy /><!--打開aop的開關，自動代理-->
</beans>

測試：

package com.asiainfo.spring;

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

public class TestSpring {
    public static void main(String[] args) {
    	
    	ApplicationContext ac = new ClassPathXmlApplicationContext("aop.xml");
    	
    	HelloBean HelloBean = (HelloBean)ac.getBean("hello");
    	
    	HelloBean.add();
	}
}

結果：

四月 25, 2016 12:37:46 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@27dd2519: startup date [Mon Apr 25 00:37:46 GMT+08:00 2016]; root of context hierarchy
四月 25, 2016 12:37:46 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [aopconfig.xml]
before
spring add

第二種：配置xml方式

   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:context="http://www.springframework.org/schema/context"
	xmlns:aop="http://www.springframework.org/schema/aop"
	xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
        <bean id="hello" class="com.asiainfo.spring.HelloBean"></bean>
        <bean id="aspect" class="com.asiainfo.spring.AspectXml"></bean>
        
        <aop:config>
          <aop:aspect id="aspectj" ref="aspect">
            <aop:pointcut expression="execution(* com.asiainfo.spring.*.add*(..))" id="pointcut"/>
            <aop:before method="before" pointcut-ref="pointcut"/>
          </aop:aspect>
        </aop:config>
</beans>

切面類：  

package com.asiainfo.spring;

public class AspectXml {
	public void before(){
		System.out.println("before");
	}
}

測試

  

package com.asiainfo.spring;

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

public class TestSpring {
    public static void main(String[] args) {
    	
    	ApplicationContext ac = new ClassPathXmlApplicationContext("aopconfig.xml");
    	
    	HelloBean HelloBean = (HelloBean)ac.getBean("hello");
    	
    	HelloBean.add();
	}
}

結果：

四月 25, 2016 12:43:26 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@27aea0c1: startup date [Mon Apr 25 00:43:26 GMT+08:00 2016]; root of context hierarchy
四月 25, 2016 12:43:26 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [aopconfig.xml]
before
spring add

其實，如果動了動態代理，那麼spring的aop是很好理解的！