![Servlets Tutorial](https://www.tutorialspoint.com/servlets/images/servlets-mini-logo.jpg)
- Servlets Tutorial
- Servlets - Home
- Servlets - Overview
- Servlets - Environment Setup
- Servlets - Life Cycle
- Servlets - Examples
- Servlets - Form Data
- Servlets - Client Request
- Servlets - Server Response
- Servlets - Http Codes
- Servlets - Writing Filters
- Servlets - Exceptions
- Servlets - Cookies Handling
- Servlets - Session Tracking
- Servlets - Database Access
- Servlets - File Uploading
- Servlets - Handling Date
- Servlets - Page Redirect
- Servlets - Hits Counter
- Servlets - Auto Refresh
- Servlets - Sending Email
- Servlets - Packaging
- Servlets - Debugging
- Servlets - Internationalization
- Servlets - Annotations
- Servlets Useful Resources
- Servlets - Questions and Answers
- Servlets - Quick Guide
- Servlets - Useful Resources
- Servlets - Discussion
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Servlets - Http Status Codes
The format of the HTTP request and HTTP response messages are similar and will have following structure −
An initial status line + CRLF ( Carriage Return + Line Feed i.e. New Line )
Zero or more header lines + CRLF
A blank line, i.e., a CRLF
An optional message body like file, query data or query output.
For example, a server response header looks as follows −
HTTP/1.1 200 OK Content-Type: text/html Header2: ... ... HeaderN: ... (Blank Line) <!doctype ...> <html> <head>...</head> <body> ... </body> </html>
The status line consists of the HTTP version (HTTP/1.1 in the example), a status code (200 in the example), and a very short message corresponding to the status code (OK in the example).
Following is a list of HTTP status codes and associated messages that might be returned from the Web Server −
Code | Message | Description |
---|---|---|
100 | Continue | Only a part of the request has been received by the server, but as long as it has not been rejected, the client should continue with the request |
101 | Switching Protocols | The server switches protocol. |
200 | OK | The request is OK |
201 | Created | The request is complete, and a new resource is created |
202 | Accepted | The request is accepted for processing, but the processing is not complete. |
203 | Non-authoritative Information | |
204 | No Content | |
205 | Reset Content | |
206 | Partial Content | |
300 | Multiple Choices | A link list. The user can select a link and go to that location. Maximum five addresses |
301 | Moved Permanently | The requested page has moved to a new url |
302 | Found | The requested page has moved temporarily to a new url |
303 | See Other | The requested page can be found under a different url |
304 | Not Modified | |
305 | Use Proxy | |
306 | Unused | This code was used in a previous version. It is no longer used, but the code is reserved |
307 | Temporary Redirect | The requested page has moved temporarily to a new url. |
400 | Bad Request | The server did not understand the request |
401 | Unauthorized | The requested page needs a username and a password |
402 | Payment Required | You cannot use this code yet |
403 | Forbidden | Access is forbidden to the requested page |
404 | Not Found | The server cannot find the requested page. |
405 | Method Not Allowed | The method specified in the request is not allowed. |
406 | Not Acceptable | The server can only generate a response that is not accepted by the client. |
407 | Proxy Authentication Required | You must authenticate with a proxy server before this request can be served. |
408 | Request Timeout | The request took longer than the server was prepared to wait. |
409 | Conflict | The request could not be completed because of a conflict. |
410 | Gone | The requested page is no longer available. |
411 | Length Required | The "Content-Length" is not defined. The server will not accept the request without it. |
412 | Precondition Failed | The precondition given in the request evaluated to false by the server. |
413 | Request Entity Too Large | The server will not accept the request, because the request entity is too large. |
414 | Request-url Too Long | The server will not accept the request, because the url is too long. Occurs when you convert a "post" request to a "get" request with a long query information. |
415 | Unsupported Media Type | The server will 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 met an unexpected condition. |
501 | Not Implemented | The request was not completed. The server did not support the functionality required. |
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 overloading or down. |
504 | Gateway Timeout | The gateway has timed out. |
505 | HTTP Version Not Supported | The server does not support the "http protocol" version. |
Methods to Set HTTP Status Code
The following methods can be used to set HTTP Status Code in your servlet program. These methods are available with HttpServletResponse object.
Sr.No. | Method & Description |
---|---|
1 | public void setStatus ( int statusCode ) This method sets an arbitrary status code. The setStatus method takes an int (the status code) as an argument. If your response includes a special status code and a document, be sure to call setStatus before actually returning any of the content with the PrintWriter. |
2 | public void sendRedirect(String url) This method generates a 302 response along with a Location header giving the URL of the new document |
3 | public void sendError(int code, String message) This method sends a status code (usually 404) along with a short message that is automatically formatted inside an HTML document and sent to the client. |
HTTP Status Code Example
Following is the example which would send a 407 error code to the client browser and browser would show you "Need authentication!!!" message.
// Import required java libraries import java.io.*; import javax.servlet.*; import javax.servlet.http.*; import java.util.*; // Extend HttpServlet class public class showError extends HttpServlet { // Method to handle GET method request. public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // Set error code and reason. response.sendError(407, "Need authentication!!!" ); } // Method to handle POST method request. public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
Now calling the above servlet would display the following result −
HTTP Status 407 - Need authentication!!!
type Status report
messageNeed authentication!!!
descriptionThe client must first authenticate itself with the proxy (Need authentication!!!).
Apache Tomcat/5.5.29