Servlet Http Status Codes

Servlet HTTP Status Codes

The format of HTTP requests and HTTP responses is similar, with the following structure:

Initial status line + carriage return line feed (CR+LF)
Zero or more header lines + carriage return line feed
A blank line, i.e., carriage return line feed
An optional message body, such as a file, query data, or query output

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

HTTP/1.1 200 OK
Content-Type: text/html
Header2: ......
HeaderN: ...
(Blank Line)
<!doctype ...><html><head>...</head><body>...</body></html>

The status line includes the HTTP version (HTTP/1.1 in this case), a status code (200 in this case), and a short message corresponding to the status code (OK in this case).

Below is a list of HTTP status codes and related information that may be returned from a 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 successful.
201	Created	The request is complete, and a new resource is created.
202	Accepted	The request has been 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. Up to five addresses are provided.
301	Moved Permanently	The requested page has been moved to a new URL.
302	Found	The requested page has been temporarily moved 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 been temporarily moved to a new URL.
400	Bad Request	The server did not understand the request.
401	Unauthorized	The requested page requires a username and password.
402	Payment Required	You cannot use this code yet.
403	Forbidden	Access to the requested page is forbidden.
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 first authenticate yourself with the proxy.
408	Request Timeout	The request took longer than the server was prepared to wait.
409	Conflict	The request could not be completed due to a conflict.
410	Gone	The requested page is no longer available.
411	Length Required	"Content-Length" is not defined. The server will not accept the request without a Content-Length.
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. This 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 incomplete. The server encountered an unexpected condition.
501	Not Implemented	The request was incomplete. The server does not support the functionality required.
502	Bad Gateway	The request was incomplete. The server received an invalid response from the upstream server.
503	Service Unavailable	The request was incomplete. The server is temporarily overloaded or down.
504	Gateway Timeout	The gateway timed out.
505	HTTP Version Not Supported	The server does not support the "HTTP protocol" version.

The following methods can be used to set HTTP status codes in a Servlet program. These methods are available through the HttpServletResponse object.

Serial No.	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 document, make sure to call setStatus before actually returning any content using PrintWriter.
2	public void sendRedirect(String url) This method generates a 302 response along with a Location header with the new document URL.
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.

The following example sends a 407 error code to the client browser, which will display the "Need authentication!!!" message.

// Import required java libraries
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
import javax.servlet.annotation.WebServlet;

@WebServlet("/showError")
// 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 will 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!!!).

YouTip

Servlet Http Status Codes

HTTP Status 407 - Need authentication!!!

Apache Tomcat/5.5.29

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