实现了聊天功能 局域网文件传输功能 分客户端和服务器端-File transfer is one of the most commonly used services on the Internet, a multi-threaded file transfer can effectively improve the file transfer speed and efficiency, this system use the Windows sockets implementation, Socket can be regarded as two network applications for communications, each an endpoint of communication.Client software and server software system points two parts, the need to use multithreading knowledge at the same time, an application can have multiple threads at the same time with the use of CPU resources, greatly strengthen the CPU utilization, but also from another aspect to speed up the transmission speed.As TCP/IP agreement linking the service is designed client/server application procedures for the mainstream standards, Therefore, the software used mainly TCP/IP agreement network communication technology　client, server from CAsyncSocket inherited category, and therefore the software is completely asynchronous communi- cation　procedures in Windows XP system