Spring4学习笔记-AOP

package com.spring.aop.impl;
 
public interface ArithmeticCalculator {
    public int add(int i, int j);
 
    public int sub(int i, int j);
 
    public int mul(int i, int j);
 
    public int div(int i, int j);
}

package com.spring.aop.impl;
 
import org.springframework.stereotype.Component;
 
@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.spring.aop.impl;
 
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
 
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.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.stereotype.Component;
 
//把这个类声明为一个切面：需要把该类放入到IOC容器中。再声明为一个切面.
@Aspect
@Component
public class LoggingAspect {
 
    /**
    *前置通知，在目标方法开始之前执行。
    *@Before("execution(public int com.spring.aop.impl.ArithmeticCalculator.add(int, int))")这样写可以指定特定的方法。
     * @param joinpoint
     */
    @Before("execution(public int com.spring.aop.impl.ArithmeticCalculator.*(int, int))")
    public void beforeMethod(JoinPoint joinpoint) {
        String methodName = joinpoint.getSignature().getName();
        List<Object>args = Arrays.asList(joinpoint.getArgs());
        System.out.println("前置通知：The method "+ methodName +" begins with " + args);
    }
 
    /**
    *后置通知，在目标方法执行之后开始执行，无论目标方法是否抛出异常。
    *在后置通知中不能访问目标方法执行的结果。
     * @param joinpoint
     */
    @After("execution(public int com.spring.aop.impl.ArithmeticCalculator.*(int, int))")
    public void afterMethod(JoinPoint joinpoint) {
        String methodName = joinpoint.getSignature().getName();
        //List<Object>args = Arrays.asList(joinpoint.getArgs());  后置通知方法中可以获取到参数
        System.out.println("后置通知：The method "+ methodName +" ends ");
    }
     
    /**
    *返回通知，在方法正常结束之后执行。
    *可以访问到方法的返回值。
     * @param joinpoint
     * @param result 目标方法的返回值
     */
    @AfterReturning(value="execution(public int com.spring.aop.impl.ArithmeticCalculator.*(..))", returning="result")
    public void afterReturnning(JoinPoint joinpoint, Object result) {
        String methodName = joinpoint.getSignature().getName();
        System.out.println("返回通知：The method "+ methodName +" ends with " + result);
    }
     
    /**
    *异常通知。目标方法出现异常的时候执行，可以访问到异常对象，可以指定在出现特定异常时才执行。
    *假如把参数写成NullPointerException则只在出现空指针异常的时候执行。
     * @param joinpoint
     * @param e
     */
    @AfterThrowing(value="execution(public int com.spring.aop.impl.ArithmeticCalculator.*(..))", throwing="e")
    public void afterThrowing(JoinPoint joinpoint, Exception e) {
        String methodName = joinpoint.getSignature().getName();
        System.out.println("返回通知：The method "+ methodName +" occurs exception " + e);
    }
     
    /**
     * 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。
     * @param point 环绕通知需要携带ProceedingJoinPoint类型的参数。
     * @return 目标方法的返回值。必须有返回值。
     */
     /*不常用
    @Around("execution(public int com.spring.aop.impl.ArithmeticCalculator.*(..))")
    public Object aroundMethod(ProceedingJoinPoint point) {
        Object result = null;
        String methodName = point.getSignature().getName();
        try {
            //前置通知
            System.out.println("The method "+ methodName +" begins with " + Arrays.asList(point.getArgs()));
            //执行目标方法
            result = point.proceed();
            //翻译通知
            System.out.println("The method "+ methodName +" ends with " + result);
        } catch (Throwable e) {
            //异常通知
            System.out.println("The method "+ methodName +" occurs exception " + e);
            throw new RuntimeException(e);
        }
        //后置通知
        System.out.println("The method "+ methodName +" ends");
        return 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: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.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.1.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd">
    <!-- 配置自动扫描包 -->
    <context:component-scan base-package="com.spring.aop.impl"></context:component-scan>
    <!-- 使AspectJ注解起作用：自动为匹配的类生产代理对象 -->
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>
</beans>

package com.spring.aop.impl;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
public class Main {
public static void main(String[] args) {
    //创建spring IOC容器
    ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
    //从IOC容器中获取bean实例
    ArithmeticCalculator arithmeticCalculator = applicationContext.getBean(ArithmeticCalculator.class);
    int result = arithmeticCalculator.add(4, 6);
    System.out.println(result);
    result = arithmeticCalculator.sub(4, 6);
    System.out.println(result);
    System.out.println(result);
    result = arithmeticCalculator.mul(4, 6);
    System.out.println(result);
    System.out.println(result);
    result = arithmeticCalculator.div(4, 0);
    System.out.println(result);
}
}