说明：  一个多线程web服务器：将编译后的WebServer.class、RequestHandler.class和index.html文件至于网络主机的同一目录中. 首先运行服务器程序,服务器运行后显示端口信息”http Server runing on port 6789”, 然后在浏览器地址栏中输入http://localhost:6789/index.html，就可以正确的显示网页。
(A multi-threaded web server: the compiled WebServer.class, RequestHandler.class and index.html file As network host in the same directory. First run the server program, the port the "http Server runing the server running on the port 6789." And then enter in the browser address bar http://localhost:6789/index.html can display Web pages correctly.)