Client.java
You should set parameter as a variable,here the parameter is the URL of the web,then it will prompt you to enter the file name in the commend Prompt window, then you will see the header of the return in commend prompt window,eg,here I set parameter "www.nwpu.edu.cn" ,when code run, It will prompt you enter the name of the file you want ,enter "link.htm",then you will receive the file link.htm
Server.java
First,put a .htm or .jpg file in the file where you place the code file ,then open a IE, enter " 127.0.0.1/XXX.jpg", then enter back,you will see the .jpg file in the I/O terminal
ThreadServee.java
It's very like the Server.java ,the major difference is that you'd better send requests rom two PC to your PC,then you will see that the two PC both can have a return message,and if the two PC both requst a XXX.htm file,both of them can get it.