AOP面向切面编程（使用注解和使用配置文件）

Aop（面向切面编程）

1. 使用注解的方式：

   1. 加入相应的jar包：

      1. com.springsource.org.aopalliance-1.0.0.jar
      2. com.springsource.org.aspectj.weaver-1.6.8.RELEASE.jar
      3. sping-aspects-4.3.3.RELEASE.jar

   2. 创建一个切面类

      package com.alibaba.wlq.invoke;
      
      import java.util.Arrays;
      
      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;
      //@Aspect:表示该类为切面类
      @Aspect
      //@Component:表示该类由Spring管理
      @Component
      public class logAspect {
          //@Before:表示before方法在被通知的程序类的方法执行之前执行
          //execution():表示需要被通知的类中的add方法，add方法可以用通配符表示，那就表示该类中所有的方法都要被通知
      	@Before(value="execution(* com.alibaba.wlq.invoke.ArithmeticImp.add(double,double))")
          //JoinPoint:是程序执行中的一个精确执行点，例如类中的一个方法。它是一个抽象的概念，在实现AOP时，并不需要去定义一个join point
      	public void before(JoinPoint joinpoint) {
              //获得被通知程序类的参数，返回类型是一个数组
      		Object[] args = joinpoint.getArgs();
              //获取被通知程序类的方法名，返回类型是字符串
      		String name = joinpoint.getSignature().getName();
      		System.out.println("alibaba------>the method "+name+" begin with"+Arrays.asList(args));
      	}
      
      	//@After:后置通知，表示在类的方法执行后、类中的return方法执行前执行
      	@After(value="execution(* com.alibaba.wlq.invoke.ArithmeticImp.add(double,double))")
      	public void after() {
      		System.out.println("alibaba------>the method *** end result");
      	}
      }
      

   3. 创建被通知的类的接口

      package com.alibaba.wlq.invoke;
      
      public interface Arithmetic {
      	public double add(double a,double b);
      }
      

   4. 创建被通知的类并且继承接口重写其中的方法

      package com.alibaba.wlq.invoke;
      
      import org.springframework.stereotype.Component;
      
      @Component
      public class ArithmeticImp implements Arithmetic{
      
      	@Override
      	public double add(double a, double b) {
      		double result = a + b;
      		System.out.println(result);
      		return result;
      	}
      
      }
      

   5. 配置文件中的配置

      <?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-4.2.xsd
      		http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.2.xsd">
      
      	<!-- 包扫描，前提加入aop的jar包 -->
      	<context:component-scan base-package="com.alibaba.wlq"></context:component-scan>
      	<!-- 开启切面注解 -->
      	<aop:aspectj-autoproxy/>
      </beans>
      

   6. 测试类

      package com.alibaba.wlq.test;
      
      import org.springframework.context.ApplicationContext;
      import org.springframework.context.support.ClassPathXmlApplicationContext;
      
      import com.alibaba.wlq.controller.UsersController;
      import com.alibaba.wlq.invoke.Arithmetic;
      import com.alibaba.wlq.invoke.ArithmeticImp;
      
      public class Test2 {
      
      	public static void main(String[] args) {
      		// TODO Auto-generated method stub
      		ApplicationContext app = new ClassPathXmlApplicationContext("app3.xml");
      		Arithmetic arith = (Arithmetic) app.getBean("arithmeticImp");
      		arith.add(15.0, 20.0);
      	}
      }
      

   7. 打印结果

      alibaba------>the method add begin with[15.0, 20.0]
      35.0
      alibaba------>the method *** end result
      

2. 使用xml配置文件

   1. 导入相应的jar包

   2. 创建接口并且创建相应的类实现该接口

      package com.alibaba.wlq.invoke;
      
      public interface Metic {
      	public double add(double a,double b);
      	public double sub(double a,double b);
      	public double mul(double a,double b);
      	public double div(double a,double b);
      }
      

      package com.alibaba.wlq.invoke;
      
      public class MeticImp implements Metic{
      
      	@Override
      	public double add(double a, double b) {
      		double result = a + b;
      		System.out.println(result);
      		return result;
      	}
      
      	@Override
      	public double sub(double a, double b) {
      		double result = a - b;
      		System.out.println(result);
      		return result;
      	}
      
      	@Override
      	public double mul(double a, double b) {
      		double result = a * b;
      		System.out.println(result);
      		return result;
      	}
      
      	@Override
      	public double div(double a, double b) {
      		double result = a / b;
      		System.out.println(result);
      		return result;
      	}
      
      }
      
      

   3. 创建切面类

      package com.alibaba.wlq.invoke;
      
      import java.util.Arrays;
      
      import org.aspectj.lang.JoinPoint;
      
      public class Invoke {
      	public void before(JoinPoint joinPoint) {
      		Object[] args = joinPoint.getArgs();
      		String name = joinPoint.getSignature().getName();
      		System.out.println("alibaba------>the method "+name+" begin with "+Arrays.asList(args));
      	}
      	public void after(JoinPoint joinPoint) {
      		String name = joinPoint.getSignature().getName();
      		System.out.println("alibaba------>the method "+name+" end result:");
      	}
      	public void afterreturn(Object result) {
      		System.out.println("result:========"+result);
      	}
      }
      

   4. 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"
      	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-4.2.xsd">
      
      	<!-- 定义被通知的程序类 -->
      	<bean id="metic" class="com.alibaba.wlq.invoke.MeticImp"></bean>
      
      	<!-- 定义切面类的Bean -->
      	<bean id="invoke" class="com.alibaba.wlq.invoke.Invoke"></bean>
      
      	<!-- 配置切面 -->
      	<aop:config>
      		<!-- 定义表达式、切点 -->
      		<aop:pointcut expression="execution(* com.alibaba.wlq.invoke.*.*(..))" id="point"/>
      		<!-- 定义切面 -->
      		<aop:aspect ref="invoke">
      			<!-- 定义前置通知 -->
      			<aop:before method="before" pointcut-ref="point" />
      			<!-- 定义后置通知 -->
      			<aop:after method="after" pointcut-ref="point"/>
      			<!-- 定义返回通知returning属性值得名称要和方法中的参数名称一致 -->
      			<aop:after-returning method="afterreturn" pointcut-ref="point" returning="result"/>
      		</aop:aspect>
      	</aop:config>
      </beans>
      

   5. 测试类

      package Test;
      
      import org.springframework.context.ApplicationContext;
      import org.springframework.context.support.ClassPathXmlApplicationContext;
      
      import com.alibaba.wlq.invoke.Metic;
      
      public class Test1 {
      	public static void main(String[] args) {
      		ApplicationContext app = new ClassPathXmlApplicationContext("app.xml");
      		Metic arith = (Metic) app.getBean("metic");
      		arith.add(15, 10);
      	}
      }	
      
      

   6. 输出结果

      alibaba------>the method add begin with [15.0, 10.0]
      25.0
      alibaba------>the method add end result:
      result:========25.0