18Spring后置通知

Spring后置通知，和前置通知类似，直接看代码：

package com.cn.spring.aop.impl;

//加减乘除的接口类

public interface ArithmeticCalculator {

    int add(int i, int j);

    int sub(int i, int j);

    int mul(int i, int j);

    int div(int i, int j);

}

package com.cn.spring.aop.impl;

import org.springframework.stereotype.Component;

//实现类

@Component

public class ArithmeticCalculatorImpl implements ArithmeticCalculator {

    @Override

    public int add(int i, int j) {

        int result = i + j;

        return result;

    }

    @Override

    public int sub(int i, int j) {

        int result = i - j;

        return result;

    }

    @Override

    public int mul(int i, int j) {

        int result = i * j;

        return result;

    }

    @Override

    public int div(int i, int j) {

        int result = i / j;

        return result;

    }

}

package com.cn.spring.aop.impl;

import org.aspectj.lang.JoinPoint;

import org.aspectj.lang.annotation.After;

import org.aspectj.lang.annotation.Aspect;

import org.aspectj.lang.annotation.Before;

import org.springframework.stereotype.Component;

import java.util.Arrays;

import java.util.List;

//把这个类声明为一个切面：首先需要把该类放入到IOC容器中，在声明为一个切面

@Aspect

@Component

public class LoggingAspect {

    //声明该方法是一个前置通知：在目标方法开始之前执行

    @Before("execution(public int ArithmeticCalculator.*(int, int))")

    public void beforeMethod(JoinPoint joinPoint) {

        String methodName = joinPoint.getSignature().getName();

        List<Object> args = Arrays.asList(joinPoint.getArgs());

        System.out.println("The method " +  methodName + " begins with " + args);

    }

    //后置通知：在目标方法执行后（无论是否发生异常），执行的通知

    //在后置通知中还不能访问目标方法执行的结果

    @After("execution(public int ArithmeticCalculator.*(int, int))")

    public void afterMethod(JoinPoint joinPoint) {

        String methodName = joinPoint.getSignature().getName();

        List<Object> args = Arrays.asList(joinPoint.getArgs());

        System.out.println("The method " +  methodName + " ends with " + args);

    }

}

package com.cn.spring.aop.impl;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {

    public static void main(String[] args) {

        //1.创建Spring的IOC容器

        ApplicationContext ctx = new ClassPathXmlApplicationContext("17-1.xml");

        //2.从IOC容器中huo获取bean的实例

        ArithmeticCalculator arithmeticCalculator = ctx.getBean(ArithmeticCalculator.class);

        //3.使用bean

        int result = arithmeticCalculator.add(3, 6);

        System.out.println("result:" + result);

    }

}

<?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.xsd

       http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd

       http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">

    <context:component-scan base-package="com.cn.spring.aop.impl">

    </context:component-scan>

    <!--使AspjectJ注解起作用：自动为匹配的类生成代理对象-->

    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>

</beans>