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方法拦截器_其它增强
===================

1 后置增强

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

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

    @Override
    public Object invoke(MethodInvocation methodInvocation) throws Throwable {
        Object object = methodInvocation.proceed();
        logger.debug("<<<< AFTER INVOKE <<<<");
        return object;
    }
}

UserServiceImpl.register
<<<< AFTER INVOKE <<<<

例程：Proxy

2 环绕增强


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

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

    @Override
    public Object invoke(MethodInvocation methodInvocation) throws Throwable {
        logger.debug(">>>> BEFORE INVOKE >>>>");
        Object object = methodInvocation.proceed();
        logger.debug("<<<< AFTER INVOKE <<<<");
        return object;
    }
}

>>>> BEFORE INVOKE >>>>
UserServiceImpl.register
<<<< AFTER INVOKE <<<<

例程：Proxy

什么样的增强操作需要在原始方法之前和之后执行？

开启事务
原始方法
提交事务

3 异常增强

还有一些增强操作需要在原始方法抛出异常的时候执行。

public class 方法拦截器 implements MethodInterceptor {
    @Override
    public Object invoke(MethodInvocation methodInvocation) throws Throwable {
        Object object = null;
        try {
            Object object = methodInvocation.proceed();
        } catch (Throwable throwable) {
            在原始方法抛出异常时执行
        }
        return object;
    }
}

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

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

    @Override
    public Object invoke(MethodInvocation methodInvocation) throws Throwable {
        Object object = null;
        try {
            logger.debug(">>>> BEFORE INVOKE >>>>");
            object = methodInvocation.proceed();
            logger.debug("<<<< AFTER INVOKE <<<<");
        } catch (Throwable throwable) {
            throwable.printStackTrace();
        }
        return object;
    }
}

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

public class UserServiceImpl implements UserService {
    ...
    @Override
    public void register(User user) {
        logger.debug("UserServiceImpl.register");
        throw new RuntimeException("This is a test exception");
    }
    ...
}

>>>> BEFORE INVOKE >>>>
UserServiceImpl.register
This is a test exception

例程：Proxy

增强操作执行的四个时机：

- 调用原始方法之前——前置增强
- 调用原始方法之后——后置增强
- 调用原始方法之前和之后——环绕增强
- 原始方法抛出异常——异常增强