一个简简单单的网络程序，可是我觉得挺有用。以前看复杂的网络程序总是云里雾里，后来才弄明白，所以编写此码，初学者用-A simple network program, but I think quite used. Ago to see the complexity of the network program is always云里雾里, then find out, so the preparation of this code, for beginners to use