Spring-AOP的五种通知方式

AOP的五种通知方式：

前置通知：在我们执行目标方法之前运行（@Before）

后置通知：在我们目标方法运行结束之后，不管有没有异常（@After）

返回通知：在我们的目标方法正常返回值后运行（@AfterReturning）

异常通知：在我们的目标方法出现异常后运行（@AfterThrowing）

环绕通知：目标方法的调用由环绕通知决定，即你可以决定是否调用目标方法，joinPoint.procced()就是执行目标方法的代码 。环绕通知可以控制返回对象(@Around)

一、导jar包

com.springsource.net.sf.cglib-2.2.0.jar
com.springsource.org.aopalliance-1.0.0.jar
com.springsource.org.aspectj.weaver-1.6.8.RELEASE.jar
commons-logging-1.1.3.jar
spring-aop-4.0.0.RELEASE.jar
spring-aspects-4.0.0.RELEASE.jar
spring-beans-4.0.0.RELEASE.jar
spring-context-4.0.0.RELEASE.jar
spring-core-4.0.0.RELEASE.jar
spring-expression-4.0.0.RELEASE.jar
spring-jdbc-4.0.0.RELEASE.jar
spring-orm-4.0.0.RELEASE.jar
spring-tx-4.0.0.RELEASE.jar
spring-web-4.0.0.RELEASE.jar
spring-webmvc-4.0.0.RELEASE.jar

二、在类路径下建applicationContext.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:context="http://www.springframework.org/schema/context"

       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
                            http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
                            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    <!--配置自动扫描的包-->
    <context:component-scan base-package="com.atguigu.spring.aop"></context:component-scan>

    <!--配置自动为匹配aspectJ 注解的Java类生成代理对象-->
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>

</beans>

三、接口

//接口
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);
}

四、实现类

package com.atguigu.spring.aop;

import org.springframework.stereotype.Component;

/**
 * @Author 谢军帅
 * @Date2019/12/6 21:23
 * @Description
 */

//实现类
@Component("arithmeticCalculator")
public class ArithmeticCalculatorImpl implements ArithmeticCalculator {
    @Override
    public int add(int i, int j) {
        int relust = i+j;
        return relust;
    }

    @Override
    public int sub(int i, int j) {
        int relust = i-j;
        return relust;
    }

    @Override
    public int mul(int i, int j) {
        int relust = i*j;
        return relust;
    }

    @Override
    public int div(int i, int j) {
        int relust = i/j;
        return relust;
    }
}

五、定义切面类

package com.atguigu.spring.aop;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.*;
import org.springframework.stereotype.Component;

import java.util.Arrays;

/**
 * @Author 谢军帅
 * @Date2019/12/11 11:17
 * @Description
 */
@Component
@Aspect
public class LoggingAspect {
    /**
     * 在每一个接口的实现类的每一个方法开始之前执行一段代码
     */

    @Before("execution(public int com.atguigu.spring.aop.ArithmeticCalculator.* (..))")
    public void beforeMethod(JoinPoint joinPoint){
        String methodName = joinPoint.getSignature().getName();
        Object[] args = joinPoint.getArgs();

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

    @After("execution(public int com.atguigu.spring.aop.ArithmeticCalculator.* (..))")
    public void afterMethod(JoinPoint joinPoint){
        String methodName = joinPoint.getSignature().getName();

        System.out.println("The method "+methodName +" end......");
    }


    /**
     * 返回通知
     * 在方法正常结束后执行的代码
     * 返回通知是可以访问方法的返回值的！
     * @param joinPoint*/
     
    @AfterReturning(value = "execution(public int com.atguigu.spring.aop.ArithmeticCalculator.* (..))",
                    returning = "result")
    public void afterReturning(JoinPoint joinPoint,Object result){
        String methodName = joinPoint.getSignature().getName();
        System.out.println("The method "+methodName +" end......result:"+result);
    }


    /**
     * 在目标方法出现异常时会执行的代码
     * 可以访问到异常对象，且可以指定在出现特定异常时在执行通知代码
     * @param joinPoint
     * @param ex*/
     
    @AfterThrowing(value = "execution(public int com.atguigu.spring.aop.ArithmeticCalculator.* (..))", throwing = "ex")
    public void afterThrowing(JoinPoint joinPoint, Exception ex){
        String methodName = joinPoint.getSignature().getName();
        System.out.println("The method "+methodName +"occurs exception :" +ex);
    }

    /**
     * 环绕通知需要携带 ProceedingJoinPoint 类型的参数
     * 环绕通知类似于动态代理的全过程：ProceedingJoinPoint 类型的参数可以决定是否执行目标方法。
     * 且环绕通知必须有返回值，返回值即为目标方法的返回值
     * @param proceedingJoinPoint
     */
    /*@Around("execution(public int com.atguigu.spring.aop.ArithmeticCalculator.* (..))")
    public Object aroundMethod(ProceedingJoinPoint proceedingJoinPoint){

        Object result = null;
        String methodName = proceedingJoinPoint.getSignature().getName();

        try {
            //前置通知
            System.out.println("The method "+methodName+" begins with "+Arrays.asList(proceedingJoinPoint.getArgs()));
            //执行目标方法
            result = proceedingJoinPoint.proceed();

            //返回通知
            System.out.println("The method ends with "+result);
        } catch (Throwable e) {
            //异常通知
            System.out.println("The method occurs exception:"+e);

            throw new RuntimeException(e);
        }

        //后置通知
        System.out.println("The method "+methodName+" ends........");

        return result;
    }*/
}

六、测试

public class Test_aop {

    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");

        ArithmeticCalculator arithmeticCalculator = (ArithmeticCalculator) context.getBean("arithmeticCalculator");

        System.out.println(arithmeticCalculator.getClass().getName());

        int result = arithmeticCalculator.add(1,2);
        System.out.println("result:"+result);

        result = arithmeticCalculator.div(200,0);
        System.out.println("result:"+result);

    }
}