spring aop demo

前置增强：

通过aop在目标逻辑代码前后增加其他功能，先创建某个类用于某个功能。例如创建服务员，用来模拟服务功能。

package AOPdemo;

public class NaiveWaiter implements Waiter {

    @Override
    public void greetTo(String name) {
        System.out.println("greetTO "+name);
    }

    @Override
    public void serveTo(String name) {
        System.out.println("serveTo "+name);
    }

}

此服务员并没有礼貌语气，通过aop添加礼貌功能，先模拟添加礼貌功能的代码

package AOPdemo;

import java.lang.reflect.Method;

import org.springframework.aop.MethodBeforeAdvice;

public class GreetBeforeAdvice implements MethodBeforeAdvice {

    @Override
    public void before(Method arg0, Object[] args, Object obj) throws Throwable {
        
        String client = (String)args[0];
        System.out.println("welcome "+client);
        
    }

}

此类通过实现MethodBeforeAdvice接口，重写前置增强方法来实现功能。arg0是目标方法的全名，args是目标方法入参，obj是目标实例。

package AOPdemo;

import org.springframework.aop.framework.ProxyFactory;

public class WaiterBerforeTest {

    public static void main(String[] args) {
        
        Waiter target = new NaiveWaiter();
        
        GreetBeforeAdvice advice = new GreetBeforeAdvice();
        
        ProxyFactory pf = new ProxyFactory();
        
        pf.setTarget(target);
        
        pf.addAdvice(advice);
        
        Waiter waiter = (Waiter)pf.getProxy();
        waiter.greetTo("kobe");
        waiter.serveTo("jordan");
        
    }
    
}

上述代码中使用ProxyFactory工厂创建代理对象，从而完成在目标方法上的增强，也可使用spring的配置方式来完成。

     <!-- aop配置 -->
     <bean id="target" class="AOPdemo.NaiveWaiter" ></bean>
     <bean id="greetBeforeAdvice" class="AOPdemo.GreetBeforeAdvice"></bean>
     
     <bean id="waiter" class="org.springframework.aop.framework.ProxyFactoryBean" 
         p:proxyInterfaces="AOPdemo.Waiter"
         p:interceptorNames="greetBeforeAdvice"
         p:target-ref="target"
     />

ProxyFactoryBean在内部使用ProxyFactory来完成。ProxyFactoryBean实现了FactoryBean来创建bean。

属性介绍：proxyInterfaces，指定代理的接口

　　　　　 interceptorNames，使用的增强

　　　　　target-ref，对目标实例进行处理

后置增强：

package AOPdemo;

import java.lang.reflect.Method;

import org.springframework.aop.AfterReturningAdvice;

public class GreetAfterAdvice implements AfterReturningAdvice {

    @Override
    public void afterReturning(Object arg0, Method arg1, Object[] arg2, Object arg3) throws Throwable {
        
        System.out.println("please enjoy yourself");
        
    }

}

     <bean id="target" class="AOPdemo.NaiveWaiter" ></bean>
     <bean id="greetBeforeAdvice" class="AOPdemo.GreetBeforeAdvice"></bean>
     <bean id="greetAfterAdvice" class="AOPdemo.GreetAfterAdvice" ></bean>
     
     <bean id="waiter" class="org.springframework.aop.framework.ProxyFactoryBean" 
         p:proxyInterfaces="AOPdemo.Waiter"
         p:interceptorNames="greetBeforeAdvice,greetAfterAdvice"
         p:target-ref="target"
     />