22.AOP开发（注解方式）

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目标类：
UserDaoImpl.java

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package com.course.dao.impl;

import org.springframework.stereotype.Component;

/**
 * 目标类
 * @author Bob
 *
 */
@Component
public class UserDaoImpl {

	public void addUser(String userName) {
		System.out.println("Save user, userName = " + userName);
		
	}

	public void deleteUser(Integer userId) {
		System.out.println("delete user, userId = " + userId);
		int[] a = new int[10];
		a[10] = 20;
	}
}

目标类：
TimeConsumption.java

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package com.course.experiment;

import org.springframework.stereotype.Component;

@Component
public class TimeConsumption {
	
	public void circulation() {
		int sum = 0;
		for (int i = 0; i < 100; i++) {
			sum = sum + i;
		}
		System.out.println("sum = " + sum);
	}
}

切面类
MyDMLAdvice.java

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package com.course.advice;

import org.aopalliance.intercept.MethodInvocation;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.After;
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;

@Component
@Aspect
public class MyDMLAdvice {

	/*
	 * 前置通知
	 */
	@Before("execution(* com.course.dao.impl.*.*(..))")
	public void openTransaction() {
		System.out.println("open transaction");
	}
	
	/*
	 * 后置通知
	 */
	@After("execution(* com.course.dao.impl.*.*(..))")
	public void commitTransaction() {
		System.out.println("commit transaction");
	}
	
	/*
	 * 环绕通知
	 */
	@Around("execution(* com.course.dao.impl.*.*(..))")
	public void dmlTransaction(ProceedingJoinPoint pj){
		
		try {
			openTransaction();
			//执行目标对象的方法
			pj.proceed();
			commitTransaction();
		} catch (Throwable e) {
			e.printStackTrace();
		}
		
	}
	
	/*
	 * 异常通知
	 */
	@AfterThrowing(value = "execution(* com.course.dao.impl.*.*(..))", throwing = "throwable")
	public void afterThrowing(Throwable throwable) throws Exception {
		System.out.println("产生异常：" + throwable.getMessage());
	}
	
	/*
	 * 计算程序执行时间(环绕通知)
	 */
	@Around("execution(* com.course.experiment.TimeConsumption.circulation(..))")
	public void computeTimeConsumption(ProceedingJoinPoint pj){
		
		try {
			long startTime = System.currentTimeMillis();
			//执行目标对象的方法
			pj.proceed();
			long endTime = System.currentTimeMillis();
			System.out.println("time consumption = " + (endTime - startTime) + " ms");
		} catch (Throwable e) {
			e.printStackTrace();
		}
		
	}
}

测试类

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package com.test;

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

import com.course.dao.impl.UserDaoImpl;
import com.course.experiment.TimeConsumption;

public class TestMain {

	public static void main(String[] args) {
		ApplicationContext applicationContext = 
				new ClassPathXmlApplicationContext("classpath:applicationContext.xml");
		
		UserDaoImpl userDaoImpl = (UserDaoImpl) applicationContext.getBean("userDaoImpl");
		
		/*
		 * 前置通知
		 * 后置通知
		 * 环绕通知
		 */
		userDaoImpl.addUser("user1");
        // open transaction
		// Save user, userName = user1
		// commit transaction
		
		/*
		 * 异常通知
		 */
		userDaoImpl.deleteUser(2);
        // delete user, userId = 2
		// 产生异常：Index 10 out of bounds for length 10
		
		/*
		 * 计算程序执行耗时
		 */
		TimeConsumption timeConsumption = applicationContext.getBean(TimeConsumption.class);
		timeConsumption.circulation();
		// sum = 4950
        // time consumption = 23 ms
		
	}
}

applicationContext.xml

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<?xml version="1.0" encoding="UTF-8"?>
<!-- 头文件 -->
<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">
        
        
	<!-- 开启扫描 -->
	<!-- 
	<context:component-scan base-package="com.course.dao.impl"></context:component-scan>
	<context:component-scan base-package="com.course.experiment"></context:component-scan>
	<context:component-scan base-package="com.course.advice"></context:component-scan>
	 -->
	<context:component-scan base-package="com.course.*"></context:component-scan>
	
	<!-- 开启注解的AOP -->
	<aop:aspectj-autoproxy></aop:aspectj-autoproxy>
	
</beans>