客户服务器通讯的select模型，面向连接的，客户端向服务器端发送请求消息建立连接，此链接是一个长连接。-Select client-server model of communication, connection-oriented, client sends a request message to the server to establish a connection, this link is a long connectio

tcp 长链接client demo 111111111111(tcp long connection client demo 111111111111)