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方法前置增强器
==============

动态代理开发的四个步骤：

- 原始类：public class UserServiceImpl implements UserService { ... }
- 增强类：public class Before implements MethodBeforeAdvice { ... }   <=
- 切入点：<aop:pointcut id="pc" expression="execution(* *(..))"/>
- 配增强：<aop:advisor advice-ref="before" pointcut-ref="pc"/>

public class 方法前置增强器 implements MethodBeforeAdvice {
                             原始方法   传递给原始方法的参数
    @Override                    |                |
    public void before(Method method, Object[] objects, Object o) throws Throwable {
        在原始方法之前执行                                     |
    }                                                       原始对象
}

/src/main/java/cn/tedu/proxy/Before.java：

public class Before implements MethodBeforeAdvice {
    private Logger logger = Logger.getLogger(Before.class);

    @Override
    public void before(Method method, Object[] objects, Object o) throws Throwable {
        logger.debug(">>>> BEFORE >>>>");
        logger.debug(method);
        for (Object object : objects)
            logger.debug(object);
        logger.debug(o);
        logger.debug(">>>>>>>>>>>>>>>>");
    }
}

>>>> BEFORE >>>>
public abstract void cn.tedu.proxy.UserService.register(cn.tedu.proxy.User)
User{username='zhangfei', password='123456'}
cn.tedu.proxy.UserServiceImpl@50de186c
>>>>>>>>>>>>>>>>
UserServiceImpl.register

>>>> BEFORE >>>>
public abstract cn.tedu.proxy.User cn.tedu.proxy.UserService.login(java.lang.String,java.lang.String)
zhangfei
123456
cn.tedu.proxy.UserServiceImpl@50de186c
>>>>>>>>>>>>>>>>
UserServiceImpl.login

>>>> BEFORE >>>>
public abstract void cn.tedu.proxy.OrderService.show(int)
1
cn.tedu.proxy.OrderServiceImpl@4f0100a7
>>>>>>>>>>>>>>>>
OrderServiceImpl.show

例程：Proxy

before方法的三个参数未必都有用，根据需要选择。