aop介绍

 AOP（Aspect Oriented Programming）,即面向切面编程，可以说是OOP（Object Oriented Programming，面向对象编程）的补充和完善。
  面向切面是面向对象中的一种方式而已。在代码执行过程中，动态嵌入其他代码，叫做面向切面编程。常见的使用场景：
i ：日志
ii： 事务
iii：数据库操作

aop的实现方式(schema)

前置通知(MethodBeforeAdvice)

@Component
public class MyBeforeAdvice implements MethodBeforeAdvice{@Overridepublic void before(Method method, Object[] args, Object target) throws Throwable {System.out.println("前置通知执行:"+method.getName());}
}

后置通知(AfterReturningAdvice)

@Component
public class AfterAdvice implements AfterReturningAdvice{@Overridepublic void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable {System.out.println("后置通知 :"+returnValue);}

环绕通知(MethodInterceptor)

@Component
public class AroundInterceptor implements MethodInterceptor{@Overridepublic Object invoke(MethodInvocation invocation) throws Throwable {System.out.println("环绕通知执行1");String msg  = (String)invocation.proceed();System.out.println("环绕通知执行2");return msg==null?null:msg.toUpperCase();}
}

异常处理通知(ThrowsAdvice)

@Component
public class MyThrowsAdvice implements ThrowsAdvice {public void afterThrowing(Exception ex){System.out.println("异常参数了:"+ex.getMessage());}}

测试类

public class Test {public static void main(String[] args) {ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");IWindow window =  ac.getBean("mytarget",IWindow.class);window.say();System.out.println("----------");System.out.println(window.doSome());}
}   

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:p="http://www.springframework.org/schema/p"xmlns:context="http://www.springframework.org/schema/context"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"><!-- 开启扫描 --><context:component-scan base-package="com.sxt.*"></context:component-scan><!-- 1.注册目标对象 --><!--        <bean class="com.sxt.pojo.Window" id="window"/>2.注册前置通知对象--><bean class="com.sxt.advice.MyBeforeAdvice" id="methodBeforeAdvice"/> <bean class="com.sxt.advice.AfterAdvice" id="afterAdvice"></bean><bean class="com.sxt.advice.AroundInterceptor" id="around"></bean><bean class="com.sxt.advice.MyThrowsAdvice" id="myThrowsAdvice"></bean> <bean class="org.springframework.aop.framework.ProxyFactoryBean" id="mytarget"><property name="target" ref="window" /><property name="interfaces" value="com.sxt.pojo.IWindow" /><property name="interceptorNames"><array><!-- 关联前置通知 --><value>methodBeforeAdvice</value><value>afterAdvice</value><value>aroundInterceptor</value><value>myThrowsAdvice</value></array></property></bean></beans>

基于aspectJ方式实现

  对于AOP这种编程思想，很多框架都进行了实现。Spring就是其中之一，可以完成面向切面编程。然而，AspectJ也实现了AOP的功能，且其实现方式更为简捷，使用更为方便，而且还支持注解式开发。所以，Spring又将AspectJ的对于AOP的实现也引入到了自己的框架中。在Spring中使用AOP开发时，一般使用AspectJ的实现方式

xml配置的方式

实体类

public class Window implements IWindow{@Overridepublic void say(){System.out.println("div  dir");}@Overridepublic String doSome(){System.out.println("你好");return "hello";}
}

切面类

public class  Advice{public void before(){System.out.println("前置通知");}public void afterReturning(){System.out.println("后置通知");}public Object around(ProceedingJoinPoint pjp) throws Throwable{System.out.println("环绕通知1");Object msg = pjp.proceed();if (msg != null) {msg = msg.toString().toUpperCase();System.out.println("环绕通知2");return msg;}return null;}public void throwing(Exception ex){System.out.println("参数异常了:"+ex.getMessage());}public void after(){System.out.println("最终通知");}
}

测试类

public class Test {public static void main(String[] args) {ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml");IWindow window =  ac.getBean(IWindow.class);window.say();System.out.println("----------");System.out.println(window.doSome());}
}   

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:p="http://www.springframework.org/schema/p"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.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd"><!-- 注册目标对象 --><bean class="com.sxt.pojo.Window" id="window"></bean><!-- 注册切面对象 --><bean class="com.sxt.advice.Advice" id="myAdvice"></bean><!-- 3.配置AOP --><aop:config><!-- 配置切面对象 --><aop:aspect ref="myAdvice"><!-- 配置切面点 --><aop:pointcut expression="execution(* com.sxt.pojo.*.*(..))" id="pointcut"/><aop:after-returning method="afterReturning" pointcut-ref="pointcut"/> <aop:before method="before" pointcut-ref="pointcut"/>   <aop:around method="around" pointcut-ref="pointcut"/>   <aop:after-throwing method="throwing" pointcut-ref="pointcut" throwing="ex"/>    <aop:after method="after" pointcut-ref="pointcut"/> </aop:aspect></aop:config></beans>

注解的方式

切面类

@Component
@Aspect
public class  Advice{@Before(value="execution(* com.sxt.*.*.*(..))")    public void before(){System.out.println("前置通知");}@AfterReturning(value="execution(* com.sxt.*.*.*(..))")  public void afterReturning(){System.out.println("后置通知");}@Around(value="execution(* com.sxt.pojo.*.*(..))")public Object around(ProceedingJoinPoint pjp) throws Throwable{System.out.println("环绕通知1");Object msg = pjp.proceed();if (msg != null) {msg = msg.toString().toUpperCase();System.out.println("环绕通知2");return msg;}return null;}@AfterThrowing(value="execution(* com.sxt.pojo.*.*(..))",throwing="ex")public void throwing(Exception ex){System.out.println("参数异常了:"+ex.getMessage());}@After(value="execution(* com.sxt.pojo.*.*(..))")public void after(){System.out.println("最终通知");}
}

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:p="http://www.springframework.org/schema/p"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.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd"><!-- 开启扫描 --><context:component-scan base-package="com.sxt.*"></context:component-scan><!-- 开启aspectJ注解 --><aop:aspectj-autoproxy></aop:aspectj-autoproxy></beans>

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