AOP之基于@Aspect 注解与Schema(xml)区别

雨点打透心脏的1/2处 2022-07-28 06:23 156阅读 0赞

# 基于@Aspect 注解 #

基于@Aspect 注解的AOP开发主要需要目标类、切面、配置文件。  
调用关系如图：  
![这里写图片描述][20160401101443075]

首先引入jar包：  
[下载jar][jar]  
目标类（HelloWorld）：

package com.demo.spring.aop;
    
    public class Helloworld {
        protected String message;//定义String 类型变量
    
        public String getMessage() {
            return message;
        }
    
        public void setMessage(String message) {
            this.message = message;
        }
    
        public void execute(){
            System.out.println("Hello"+getMessage()+"!");
        }
    
    }

切面：

package com.demo.spring.aop;
    
    import org.aspectj.lang.JoinPoint;
    import org.aspectj.lang.ProceedingJoinPoint;
    import org.aspectj.lang.annotation.After;
    import org.aspectj.lang.annotation.Around;
    import org.aspectj.lang.annotation.Aspect;
    import org.aspectj.lang.annotation.Before;
    import org.aspectj.lang.annotation.Pointcut;
    
    @Aspect
    public class MyAspect { 
    
        /** * 定义切入点函数 */
        @Pointcut("execution(* com.demo.spring.aop.*.execute*(..))")
        void pointcut(){
    
        }
        /** * 使用@Before声明前置通知 * @param thisJoinPoint */
        @Before("pointcut()")
        public void beforeExecute(JoinPoint thisJoinPoint){
            System.out.println("start to say:");
        }
        /** * 使用@Around 注解声明环绕通知 * @param thisJoinPoint * @return * @throws Throwable */
        @Around("pointcut()")
        public Object userOperate(ProceedingJoinPoint thisJoinPoint) throws Throwable{
            System.out.println("before 之前");
            Object va=thisJoinPoint.proceed();
            System.out.println("after 之前");
            return va;
        }
        /** * 使用@After 注解声明后置通知 * @param thisJoinPoint */
        @After("pointcut()")
        public void afterExecute(JoinPoint thisJoinPoint){
            System.out.print("end!");
        }
    }

applicationContext.xml配置文件：

客户端调用：  
package com.demo.spring.aop;

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

public class Test \{

public static void main(String[] args) {
        ApplicationContext ctx=new FileSystemXmlApplicationContext("WebRoot/WEB-INF/applicationContext.xml");
        Helloworld hello=(Helloworld) ctx.getBean("Helloworld");
        hello.execute();
    }

\}  
这中方式主要是用Spring的注解方式开发AOP，还有一种是通过Schema(xml)的方式

# 基于Schema(xml) #

与@Aspect注解相比不同之处主要在切面类与配置文件上，切面类不再用注解，而是在配置文件中配置增强  
切面类：

package com.demo.spring.aop;
    
    import org.aspectj.lang.JoinPoint;
    import org.aspectj.lang.ProceedingJoinPoint;
    import org.aspectj.lang.annotation.Aspect;
    
    /** * 切面类 * @author dandan * */
    @Aspect
    public class MyAspect { 
        /** * 前置通知 * @param thisJoinPoint */
        public void beforeExecute(JoinPoint thisJoinPoint){
            System.out.println("start to say：");
        }
        /** * 环绕通知类 * @param thisJoinPoint * @return * @throws Throwable */
        public Object userOperate(ProceedingJoinPoint thisJoinPoint) throws Throwable{
            return thisJoinPoint.proceed();
        }
        /** * 后置通知类 * @param thisJoinPoint */
        public void  afterExecute(JoinPoint thisJoinPoint){
            System.out.println("end!");
        }
    }

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:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd">
        <bean id="HelloWorld" class="com.demo.spring.aop.HelloWorld">
            <property name="message">
                <value>World</value>
            </property>
        </bean>
        <bean id="myAspect" class="com.demo.spring.aop.MyAspect"></bean>
        <aop:config>
            
            <aop:aspect id="aopAspect" ref="myAspect">
                
                <aop:pointcut id="pointcut" expression="execution(* execute(..)) and target(com.demo.spring.aop.HelloWorld)"/>
                
                <aop:before pointcut-ref="pointcut" method="beforeExecute"/>
                <aop:around pointcut-ref="pointcut" method="userOperate"/>
                <aop:after pointcut-ref="pointcut" method="afterExecute"/>
            </aop:aspect>
        </aop:config>
    </beans>

[20160401101443075]: /images/20220727/bc9c790e46734189ac952c35daeffb75.png
[jar]: http://download.csdn.net/detail/wangdan199112/9478633