详细了解MVC+proxy

/**
 * 创建目标接口，定义目标接口要完成的功能
 */
public interface UserService {
    boolean save(User user);
}

/**
 * 创建目标接口，定义目标接口要完成的功能
 */
public interface UserService {
    boolean save(User user);
}

public class UserServiceImpl implements UserService {
    private UserDao dao=new UserDaoImpl();
    @Override
    public boolean save(User user) {
        boolean success=false;
        success=dao.insert(user);
        return success;
    }
}

public class UserDaoImpl implements UserDao {
    @Override
    public boolean insert(User user) {
        System.out.println("insert into t_user (username,password)values('"+user.getUsername()+"','"+user.getPassword()+"')");
        return true;
    }
}

public class UserHandler implements InvocationHandler {

    //动态创建目标对象
    Object target=null;
    public UserHandler(Object target){
        this.target=target;
    }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        //返回值
        Object result=null;
        //增强功能
        System.out.println("begin Transaction.....");
        result=result=method.invoke(target,args);
        System.out.println("commit Transaction.....");
        System.out.println("rollback Transaction.....");
        System.out.println("end Transaction.....");
        //返回值
        return result;
    }
}

public class UserSaveServlet {
    public static void main(String[] args) throws Exception {
        //需要调用的目标类
        Class c= UserServiceImpl.class;
        Object obj = c.newInstance();
        //获取该类的类加载器
        ClassLoader loader = obj.getClass().getClassLoader();
        //目标对象实现的接口
        Class<?>[] interfaces=obj.getClass().getInterfaces();
        //获取InvocationHandler对象
        InvocationHandler handler=new UserHandler(obj);
        //创建代理对象
        //将返回值转为接口类型
        UserService service=(UserService)Proxy.newProxyInstance(loader,interfaces,handler);
        boolean success=service.save(new User("张三","123456"));
        System.out.println(success?"保存成功":"保存失败");
    }
}