说明：  客户端，使用Socket对网络上某一个服务器的某一个端口发出连接请求，一旦连接成功，打开会话；会话完成后，关闭Socket。客户端不需要指定打开的端口，通常临时的、动态的分配一个1024以上的端口。 服务器，使用ServerSocket监听指定的端口，端口可以随意指定（由于1024以下的端口通常属于保留端口，在一些操作系统中不可以随意使用，所以建议使用大于1024的端口），等待客户连接请求，客户连接后，会话产生；在完成会话后，关闭连接。
(Client, use the Socket on one server on the network a port for a connection request, once the connection is successful, open the session session is complete, close the Socket. Clients do not need to specify the port to open, usually temporary, dynamically allocate a port above 1024. Server, use ServerSocket listen on the specified port, the port can specify (usually because ports below 1024 are reserved ports, in some operating systems can not be free to use, it is recommended to use a port greater than 1024), waiting for client connection request, the client connection, the session produced in the session is finished, close the connection.)