Servlet HTTP status code and get browser URL

Servlet HTTP Status code

The format of the HTTP request and HTTP response message is similar, with the following structure:

• Initial status line + carriage return newline character (carriage return + line feed)
• 0 or more header lines + carriage return line break
• A blank line, the carriage return line break
• An optional message body, such as file, query data, or query output

For example, the server's response header looks like this:

http/1.1 okcontent-type:text/htmlheader2: ... HeaderN:  ... (Blank line) <!doctype ... >
The status line includes the HTTP version (in this case, http/1.1), a status code (200 in this example), and a short message that corresponds to the status code (OK in this case).
The following is a list of HTTP status codes and related information that may be returned from the WEB server:

 
 

  
  
 
   
 
    
Code
 
    
message
 
    
Description
 
   
 
   
 
    
100
 
    
Continue
 
    
Only part of the request has been received by the server, but as long as it is not rejected, the client should continue the request.
 
   
 
   
 
    
101
 
    
Switching protocols
 
    
Server switching protocol.
 
   
 
   
 
    
200
 
    
Ok
 
    
The request was successful.
 
   
 
   
 
    
201
 
    
Created
 
    
The request is complete, and a new resource is created.
 
   
 
   
 
    
202
 
    
Accepted
 
    
The request is accepted for processing, but the processing is incomplete.
 
   
 
   
 
    
203
 
    
Non-authoritative Information
 
    
 
   
 
   
 
    
204
 
    
No Content
 
    
 
   
 
   
 
    
205
 
    
Reset Content
 
    
 
   
 
   
 
    
206
 
    
Partial Content
 
    
 
   
 
   
 
    
300
 
    
Multiple Choices
 
    
A list of links. The user can select a link to go to that location. Maximum of five addresses.
 
   
 
   
 
    
301
 
    
Moved Permanently
 
    
The requested page has been transferred to a new URL.
 
   
 
   
 
    
60W
 
    
Found
 
    
The requested page has been temporarily transferred to a new URL.
 
   
 
   
 
    
303
 
    
See other
 
    
The requested page can be found under another different URL.
 
   
 
   
 
    
304
 
    
Not Modified
 
    
 
   
 
   
 
    
305
 
    
Use Proxy
 
    
 
   
 
   
 
    
306
 
    
Unused
 
    
Use this code in a previous version. It is no longer used, but the code is still preserved.
 
   
 
   
 
    
307
 
    
Temporary Redirect
 
    
The requested page has been temporarily transferred to a new URL.
 
   
 
   
 
    
400
 
    
Bad Request
 
    
The server does not understand the request.
 
   
 
   
 
    
401
 
    
Unauthorized
 
    
The requested page requires a user name and password.
 
   
 
   
 
    
402
 
    
Payment Required
 
    
You cannot use this code yet.
 
   
 
   
 
    
403
 
    
Forbidden
 
    
Access to the requested page is forbidden.
 
   
 
   
 
    
50U
 
    
Not Found
 
    
The server was unable to find the requested page.
 
   
 
   
 
    
405
 
    
Method not allowed
 
    
The method specified in the request is not allowed.
 
   
 
   
 
    
50W
 
    
Not acceptable
 
    
The server only generates a response that is not accepted by the client.
 
   
 
   
 
    
407
 
    
Proxy Authentication Required
 
    
You must use Proxy server authentication before requesting delivery.
 
   
 
   
 
    
408
 
    
Request Timeout
 
    
The request takes longer than the server can wait to time out.
 
   
 
   
 
    
409
 
    
Conflict
 
    
The request could not be completed because of a conflict.
 
   
 
   
 
    
410
 
    
Gone
 
    
The requested page is no longer available.
 
   
 
   
 
    
411
 
    
Length Required
 
    
"Content-length" is undefined. The server cannot process request information sent by the client without content-length.
 
   
 
   
 
    
412
 
    
Precondition Failed
 
    
The prerequisites given in the request are evaluated by the server as false.
 
   
 
   
 
    
413
 
    
Request Entity Too Large
 
    
The server does not accept the request because the request entity is too large.
 
   
 
   
 
    
414
 
    
Request-url Too Long
 
    
The server does not accept the request because the URL is too long. Occurs when you convert a "post" request to a "get" request with long query information.
 
   
 
   
 
    
415
 
    
Unsupported Media Type
 
    
The server does not accept the request because the media type is not supported.
 
   
 
   
 
    
417
 
    
Expectation Failed
 
    
 
   
 
   
 
    
500
 
    
Internal Server Error
 
    
The request was not completed. The server encountered an unexpected situation.
 
   
 
   
 
    
501
 
    
Not implemented
 
    
The request was not completed. The server does not support the required functionality.
 
   
 
   
 
    
502
 
    
Bad Gateway
 
    
The request was not completed. The server received an invalid response from the upstream server.
 
   
 
   
 
    
503
 
    
Service unavailable
 
    
The request was not completed. The server is temporarily overloaded or crashed.
 
   
 
   
 
    
504
 
    
Gateway Timeout
 
    
The gateway timed out.
 
   
 
   
 
    
505
 
    
HTTP Version not supported
 
    
The server does not support the "HTTP protocol" version.
 
   
 
  
 
 
How to set the HTTP status code
The following methods can be used to set the HTTP status code in a Servlet program. These methods are available through the  httpservletresponse  object. 

 
 

  
  
 
   
 
    
Serial Number
 
    
 Method & Description
 
   
 
   
 
    
1
 
    
Public void SetStatus (int statusCode) This method sets an arbitrary status code. The SetStatus method takes an int (status code) as a parameter. If your response contains a special status code and documentation, make sure to    call SetStatus before using PrintWriter to actually return any content. 
 
   
 
   
 
    
2
 
    
Public void Sendredirect (String URL) The method generates a 302 response, along with a location header with a new document URL    . 
 
   
 
   
 
    
3
 
    
Public void Senderror (int code, String message) This method sends a status code (typically 404), along with a short message that is automatically formatted and sent to the client inside the HTML document.
 
   
 
  
 
 
HTTP status code and get URL instance
The following example notes the code that sends the 407 error and sends the redirect, which is used to output the obtained URL information.
  Statuscode.java 
Package Hentai.servlet;import Java.io.ioexception;import Javax.servlet.servletexception;import Javax.servlet.annotation.webservlet;import Javax.servlet.http.httpservlet;import Javax.servlet.http.httpservletrequest;import javax.servlet.http.httpservletresponse;/** * servlet implementation Class StatusCode */@WebServlet ("/statuscode") public class StatusCode extends HttpServlet {private static final long seria           Lversionuid = 1L;        /** * @see httpservlet#httpservlet () */public StatusCode () {super (); TODO auto-generated Constructor stub}/** * @see Httpservlet#doget (httpservletrequest request, HttpServletResponse R esponse) */protected void doget (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {//TODO auto-generated Method Stub//response.senderror (407, "https://www.baidu.com/");// Response.sendredirect ("https://www.baidu.com/"); Response.getwriter (). Append ("Served at:"). Append ( Request.getcontextpath ()); RespoNse.getwriter (). Append ("<br/>url:"). Append (Request.getscheme () + "://" +request.getservername () + ":" + Request.getserverport () +request.getcontextpath () +request.getservletpath ()), Response.getwriter (). Append ("<br />requesturl: "). Append (Request.getrequesturl ()); Response.getwriter (). Append (" <br/> "+ Request.getservletcontext (). toString ()); Response.getwriter (). Flush (); /** * @see Httpservlet#dopost (httpservletrequest request, httpservletresponse response) */protected void DoPost ( HttpServletRequest request, HttpServletResponse response) throws Servletexception, IOException {//TODO auto-generated Method Stubdoget (Request, Response);}}
Servlet HTTP status code and get browser URL