Spring AOP 详解

转载于one_piece20的博客，原文地址：http://blog.csdn.net/kuangfengbuyi/article/details/52487657

Spring AOP的几个概念

1.切面(Aspect)：切面就是一个关注点的模块化，如事务管理、日志管理、权限管理等； 
2.连接点(Joinpoint)：程序执行时的某个特定的点，在Spring中就是一个方法的执行； 
3.通知(Advice)：通知就是在切面的某个连接点上执行的操作，也就是事务管理、日志管理等； 
4.切入点(Pointcut)：切入点就是描述某一类选定的连接点，也就是指定某一类要织入通知的方法； 
5.目标对象(Target)：就是被AOP动态代理的目标对象； 
借助下图进行理解： 

先来了解切面编程的使用 

前置增强

创建一个前置增强类

package cjq.demo.spring.aop;import org.springframework.aop.MethodBeforeAdvice;import java.lang.reflect.Method;/** * author: cjianquan * date: 2016/9/9 */public class GreetingBeforeAdvice implements MethodBeforeAdvice {    @Override    public void before(Method method, Object[] args, Object target) throws Throwable {        System.out.println("GreetingBeforeAdvice Before");    }}
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后置增强

package cjq.demo.spring.aop;import org.springframework.aop.AfterReturningAdvice;import java.lang.reflect.Method;/** * author: cjianquan * date: 2016/9/9 */public class GreetingAfterAdvice implements AfterReturningAdvice {    @Override    public void afterReturning(Object result, Method method, Object[] args, Object target) throws Throwable {        System.out.println("GreetingAfterAdvice After");    }}
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测试代码：

    @Test    public void test_springAop(){        ProxyFactory proxyFactory = new ProxyFactory();     // 创建代理工厂        proxyFactory.setTarget(new GreetingImpl());         // 射入目标类对象        proxyFactory.addAdvice(new GreetingBeforeAdvice()); // 添加前置增强        proxyFactory.addAdvice(new GreetingAfterAdvice());  // 添加后置增强        Greeting greeting = (Greeting) proxyFactory.getProxy(); // 从代理工厂中获取代理        greeting.sayHello("Jack");    }
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当然，我们完全可以只定义一个增强类，让它同时实现 MethodBeforeAdvice 与 AfterReturningAdvice 这两个接口，如下 

package cjq.demo.spring.aop;import org.springframework.aop.AfterReturningAdvice;import org.springframework.aop.MethodBeforeAdvice;import java.lang.reflect.Method;/** * author: cjianquan * date: 2016/9/9 */public class GreetingBeforeAndAfterAdvice implements MethodBeforeAdvice, AfterReturningAdvice {    @Override    public void before(Method method, Object[] args, Object target) throws Throwable {        System.out.println(" GreetingBeforeAndAfterAdvice  Before");    }    @Override    public void afterReturning(Object result, Method method, Object[] args, Object target) throws Throwable {        System.out.println("GreetingBeforeAndAfterAdvice  After");    }}
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测试代码：

    @Test    public void test_springAop1(){        ProxyFactory proxyFactory = new ProxyFactory();     // 创建代理工厂        proxyFactory.setTarget(new GreetingImpl());         // 射入目标类对象        proxyFactory.addAdvice(new GreetingBeforeAndAfterAdvice()); // 添加增强        Greeting greeting = (Greeting) proxyFactory.getProxy(); // 从代理工厂中获取代理        greeting.sayHello("Jack");    }
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环绕增强

package cjq.demo.spring.aop;import org.aopalliance.intercept.MethodInterceptor;import org.aopalliance.intercept.MethodInvocation;import org.springframework.stereotype.Component;/** * author: cjianquan * date: 2016/9/9 */@Component("greetingAroundAdvice")public class GreetingAroundAdvice implements MethodInterceptor {    @Override    public Object invoke(MethodInvocation invocation) throws Throwable {        before();        Object result = invocation.proceed();        after();        return result;    }    private void before() {        System.out.println("GreetingAroundAdvice  Before");    }    private void after() {        System.out.println("GreetingAroundAdvice  After");    }}
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测试代码：

    @Test    public void test_greetingAroundAdvice(){        ProxyFactory proxyFactory = new ProxyFactory();     // 创建代理工厂        proxyFactory.setTarget(new GreetingImpl());         // 射入目标类对象        proxyFactory.addAdvice(new GreetingAroundAdvice()); // 添加增强        Greeting greeting = (Greeting) proxyFactory.getProxy(); // 从代理工厂中获取代理        greeting.sayHello("Jack");    }
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前置增强、后置增强、环绕增强的接口类图：

转载于one_piece20的博客，原文地址：http://blog.csdn.net/kuangfengbuyi/article/details/52487657