套接字连接超时设计方案：在使用tcp进行网络通信时，由于受到网路传输速度的限制，所以经常会导致套接字连接占用很长时间。本程序实现用户要求3秒中没有建立连接，就认为连接失败，要求重新连接来避免这种情况。-Socket connection timeout design: tcp in the use of network communications, the transmission speed of the network due to the restrictions, so often lead to socket connection occupied for a long time. This procedure user requirements to achieve three seconds does not establish a connection, that the connection fails, request to re-connect to avoid this situation.