输出日志实例改成用Spring的AOP来实现

1.采用Interception Around通知的形式实现

Interception Around通知会在Join Point的前后执行，实现Interception Around通知的类需要实现接口MethodInterceptor。其实现思路是：

1）首先实现接口MethodInterceptor，在Invoke()方法里编写负责输出日志信息的代码，具体业务逻辑还使用前面的接口TimeBookInterface和它的实现类TimeBook

2）然后在Spring的配置文档中定义PointCut

3）最后编写测试程序，执行，查看输出

1）编写负责输出日志信息的类LogAround

//****LogAround.java****
package com.gc.action

import org.aopalliance.interceptor.MethodInvocation;
import org.aopalliance.interceptor.MethodInterceptor;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;

//Interception Around通知会在Join Point的前后执行
public class LogAround implements MethodIntercetor{
      private Logger logger = Logger.getLogger(this.getClass().getName());
      //负责输出日志信息的代码
     public Object invoke(MethodInvocation mi) throw Throwabel{
           logger.log(Level.INFO,mi.getArguments()[]+"开始审核数据...");
         try{
            Object result = mi.proceed();
            return result;
             }
         finally{
             logger.log(Level.INFO,mi.getArguments()[]+"审核数据结束...")
                }
}
}    

参数MethodInvocation:通过它可以获得方法的名称，程序传入的参数Object[]等

proceed方法，通过它即可执行被调用的方法

return result，返回值为被调用方法的返回值

com.gc.impl包中的接口和 com.gc.action包中的类

//*****TimeBookInterface.java****

package com.gc.impl;
import org.apache.log4j.Level;

public interface TimeBookInterface{

    public void doAuding(String name);
}

//*****TimeBook.java*******
package com.gc.action;
import com.gc.impl.TimeBookInterface;

public class TimeBook implements TimeBookInterface{
         public void doAuditing(String name){
         ....
}
}

2）定义Spring的配置文档config.xml

<!xml version="1.0" encoding = "UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
 "http://www.springframework.org/dtd/spring-beans.dtd"
>
<beans>
     <bean id="HelloWorld" class = "com.gc.action.HelloWorld" depends-on="date">
          <property name = "msg">
               <value>HelloWorld</value>
         </property>
         <property name = "date">
              <ref bean = "date"/>
        </property>
    </bean>
    <bean id="date" class="java.util.Date"/>

    <bean id="log" class="com.gc.action.LogAround"/>
    <bean id="timeBook" class="com.gc.action.TimeBook"/>
    <bean id="logProxy" class="org.springframework.aop.framework.ProxyFactoryBean">
        <property name="proxyInterfaces">
               <value>com.gc.impl.TimeBookInterface</value>
        </property>
       <property name="target">
          <ref Bean="timeBook"/>
       </proterty>
       <property name="interceportNames">
          <list>
               <value>log</value>
         </list>
      </property>
   </bean>
</beans>

id为log的Bean，负责输出日志信息；

id为timeBook的Bean，负责具体的业务逻辑考勤审核

id为logProxy的Bean，使用Spring提供的ProxyFactoryBean来实现代理，在该Bean里定义相关的属性，包括要代理的接口，目标类急要使用的Interceptor。

3）测试代码

 //******TestHelloWorld*********

 package com.gc.test;

 import com.gc.action.TimeBook;
 import com.gc.aciton.TimeBookProxy;
 import com.gc.impl.TimeBookInterface;
 public class TestHelloWorld{
       public static void main(String[] args){
           ApplicationContext actx = new FileSystemXmlApplicationContext("config.xml");
           TimeBookInterface timeBookProxy = (TimeBookInterface)actx.getBean("logProxy");
         timeBookProxy.doAuditing("张三");
 }

 }