clientcallback

代码说明：

  实现客户端回调的一段源码，可能对用不到这些得人没有什么用处，但用到了在去找很麻烦的，所以传上来与大家共享了(To achieve the client callback section of source code, may be less than those who were of no use, but used in very troublesome to find, therefore, Chuan-up and share the)