Application of common methods based on HttpServletRequest

Referer:

Public void referer (HttpServletRequest request, HttpServletResponse response)
Throws Exception {
String referer = request. getHeader ("referer ");
If (referer = null |! Referer. startsWith ("http: // localhost ")){
Response. sendRedirect ("/webTwo/index. jsp ");
Return;
}
String data = "welcome ";
Response. getOutputStream (). write (data. getBytes ());
}

URL writing skills:
Write '/' first, so you do not need to write the web application name for the server; Add the web application name for the browser;

RequestDispatcher:
// Request forwarding. The Request domain object is used to bring data to the forwarding resource;
Difference from redirection: the client sends a request only once and the server calls multiple resources without changing the address bar of the client browser;

Obtaining method:
ServletContext. getRequestDispatcher (String );
ServletContext. getNamedDispatcher (String );
ServletRequest. getRequestDispatcher (String );
Ex: request. getRequestDispatcher ("/index. jsp"). forward (request, response );

Encoder: Garbled Processing
Request. setCharacterEncoding ("UTF-8"); // valid only for Post Mode
// Handle garbled characters in get Mode
String value = request. getParameter ("username ");
String out = new String (value. getBytes ("iso8859-1"), "UTF-8 ");
System. out. println (out );
// Check the request data before using it.

GET Header:

// String value = request. getHeader ("headername ");
// Enumeration headers = request. getHeaders ("");
// Enumeration headernames = request. getHeaderNames ();