echo服务器示例程序，当收到客户端的数据，服务器把数据不经加工地发送给客户。采用TCP连接，采用端口8080进行设计，在整个过程中主要涉及socket的通信。-echo server sample application, when received by the client data, the server does not re-processing the data sent to clients. The use of TCP connection, using port 8080 to design, in the entire process mainly involves the communication socket.