spring 5种通知

方法实现接口

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);
}

接口实现类

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;
    }
}

xml文件配置

<?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: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>

通知切面

package com.cn.spring.aop.impl;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
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 {

@Pointcut("execution(** ArithmeticCalculator.*(..))")
public void declareJointPointExpression(){

}
//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))")

//前置通知
@Before("declareJointPointExpression()")
public void beforeMethod(JoinPoint joinPoint) {
String methodName = joinPoint.getSignature().getName();
List<Object> args = Arrays.asList(joinPoint.getArgs());
Object target = joinPoint.getTarget();
System.out.println("The method " + methodName + " begins with " + args + target);
}

//后置通知
    @After("execution(** ArithmeticCalculator.*(int, int))")
    public void afterMethod(JoinPoint joinPoint){
        String methodName = joinPoint.getSignature().getName();
        System.out.println("The method " +  methodName + " ends ");
    }
    //返回通知，在方法正常结束后执行的方法，可以访问到方法的返回值
    @AfterReturning(value="execution(** ArithmeticCalculator.*(int, int))",
            returning = "result")
    public void afterReturning(JoinPoint joinPoint , Object result){
        String methodName = joinPoint.getSignature().getName(); 

        System.out.println("The method " +  methodName + " ends with " + result);
    }
    //异常通知
    @AfterThrowing(value="execution(** ArithmeticCalculator.*(int, int))",
            throwing = "ex")
    public void afterThrowing(Exception ex){

        System.out.println(ex);
    }

}

/*
 * JoinPoint访问到连接点上下文的信息
 * JoinPoint
             java.lang.Object[] getArgs()：获取连接点方法运行时的入参列表；
             Signature getSignature() ：获取连接点的方法签名对象；
             java.lang.Object getTarget() ：获取连接点所在的目标对象；
              java.lang.Object getThis() ：获取代理对象本身；
 * */

环绕通知类似于动态代理的全过程

如果环绕通知返回100，则结果为100

//功能最强大的环绕通知
    //ProceedingJoinPoint 类型的参数可以决定是否执行目标方法
    @Around("execution(** ArithmeticCalculator.*(..))")
    public Object aroundMethod(ProceedingJoinPoint pjd){
        Object result = null ;
        String methodName = pjd.getSignature().getName();

        try {
            System.out.println("before");
            result = pjd.proceed();
            System.out.println("after " + result);
        } catch (Throwable e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            System.out.println("Exception " + e);
        }
        System.out.println("return " + result);
        return result;
    }