回调函数的理论我说不上多少，但以前给同事写的类中用到过，这次面试中又被问到相关的理论，故将其 摘录出来，做一个实例，以后参考。-Callback function of the theory I can not say how much was formerly a colleague used to write De Lei Zhong Guo, they asked in the interview relevant theories, Gu be extracted out an