*、request.getContextPath();
What gets is: /+ project folder name
*、request.getScheme();
What is obtained is: protocol name such as http
*、request.getServerName();
What is obtained is: service name or domain name
*、request.getServerPort();
What is obtained is: the port number of the server
*, Get the parameter information in the xml file in the java class
request.getSession().getServletContext().getInitParameter(key);