javax.servlet.http
Class HttpServlet

java.lang.Object
  |
  +--javax.servlet.GenericServlet
        |
        +--javax.servlet.http.HttpServlet

public abstract class HttpServlet

extends GenericServlet

implements java.io.Serializable

The mother-of-all-HttpServlets. Every normal http servlet extends this class and overrides either the doGet or doPost methods (or both). The server calls service. Service in its turn calls doGet, doPost, whatever, depending on the client's request.

Since:

Servlet API 1.0

Version:

Servlet API 2.1

See Also:

Serialized Form

Constructor Summary

HttpServlet()
Does nothing

Method Summary

protected void	doDelete(HttpServletRequest request, HttpServletResponse response) This method is called on a "DELETE" request.
protected void	doGet(HttpServletRequest request, HttpServletResponse response) This method is called on a "GET" request.
protected void	doOptions(HttpServletRequest request, HttpServletResponse response) This method is called on a "OPTIONS" request.
protected void	doPost(HttpServletRequest request, HttpServletResponse response) This method is called on a "POST" request.
protected void	doPut(HttpServletRequest request, HttpServletResponse response) This method is called on a "PUT" request.
protected void	doTrace(HttpServletRequest request, HttpServletResponse response) This method is called on a "TRACE" request.
protected long	getLastModified(HttpServletRequest request) Returns the time the requested uri was last modified in seconds since 1 january 1970.
protected void	service(HttpServletRequest request, HttpServletResponse response) This method looks whether the request is a POST, GET, etc method, and then calls the appropriate doPost, doGet, whatever method. If the request method is something it can't handle it sends a HttpServletResponse.SC_BAD_REQUEST error through the response.
void	service(ServletRequest request, ServletResponse response) Frontend for calling service(HttpServletRequest,HttpServletResponse).

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, init, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HttpServlet

public HttpServlet()

Does nothing

Since:

Servlet API 1.0

Method Detail

doDelete

protected void doDelete(HttpServletRequest request,
                        HttpServletResponse response)
                 throws ServletException,
                        java.io.IOException

This method is called on a "DELETE" request. The default implementation is that HttpServletResponse.SC_BAD_REQUEST (error nr: 400) and the message "Method \"DELETE\" is not supported by this servlet" is returned to the client.

Throws:

ServletException - if an Servlet Exception occurs

java.io.IOException - if an IOException occurs

Since:

Servlet API 2.0

doGet

protected void doGet(HttpServletRequest request,
                     HttpServletResponse response)
              throws ServletException,
                     java.io.IOException

This method is called on a "GET" request. The default implementation is that HttpServletResponse.SC_BAD_REQUEST (error nr: 400) and the message "Method \"GET\" is not supported by this servlet" is returned to the client.

Throws:

ServletException - if an Servlet Exception occurs

java.io.IOException - if an IOException occurs

Since:

Servlet API 1.0

doOptions

protected void doOptions(HttpServletRequest request,
                         HttpServletResponse response)
                  throws ServletException,
                         java.io.IOException

This method is called on a "OPTIONS" request. It tells the client which methods are supported by the servlet.
This comes down to an implementation where HEAD, TRACE and OPTIONS are supported by default because this class contains default implementations of them. GET, POST, DELETE and PUT are added to this list if the subclass has its own implementation of the doGet, doPost, doDelete or doPut method respectively. Note:
This implementation is probably not the most efficient one, but the whole OPTIONS thing is intended for debugging purposes, and this implementation does the job.

Throws:

ServletException - if an Servlet Exception occurs

java.io.IOException - if an IOException occurs

Since:

Servlet API 2.0

doPost

protected void doPost(HttpServletRequest request,
                      HttpServletResponse response)
               throws ServletException,
                      java.io.IOException

This method is called on a "POST" request. The default implementation is that HttpServletResponse.SC_BAD_REQUEST (error nr: 400) and the message "Method \"POST\" is not supported by this servlet" is returned to the client.

Throws:

ServletException - if an Servlet Exception occurs

java.io.IOException - if an IOException occurs

Since:

Servlet API 1.0

doPut

protected void doPut(HttpServletRequest request,
                     HttpServletResponse response)
              throws ServletException,
                     java.io.IOException

This method is called on a "PUT" request. The default implementation is that HttpServletResponse.SC_BAD_REQUEST (error nr: 400) and the message "Method \"PUT\" is not supported by this servlet" is returned to the client.

Throws:

ServletException - if an Servlet Exception occurs

java.io.IOException - if an IOException occurs

Since:

Servlet API 2.0

doTrace

protected void doTrace(HttpServletRequest request,
                       HttpServletResponse response)
                throws ServletException,
                       java.io.IOException

This method is called on a "TRACE" request. This method is for debugging purposes.
When a client makes a TRACE request the following is returned:
content type = "message/http"
message size: <size of the complete message>
first line of the message : TRACE <requested uri> <protocol>
on the following lines all the request header names and values

Throws:

ServletException - if an Servlet Exception occurs

java.io.IOException - if an IOException occurs

Since:

Servlet API 2.0

getLastModified

protected long getLastModified(HttpServletRequest request)

Returns the time the requested uri was last modified in seconds since 1 january 1970. Default implementation returns -1.

Since:

Servlet API 1.0

service

protected void service(HttpServletRequest request,
                       HttpServletResponse response)
                throws ServletException,
                       java.io.IOException

This method looks whether the request is a POST, GET, etc method, and then calls the appropriate doPost, doGet, whatever method.
If the request method is something it can't handle it sends a HttpServletResponse.SC_BAD_REQUEST error through the response.

Throws:

ServletException - an error has occured

java.io.IOException - an error has occured

Since:

Servlet API 1.0

service

public void service(ServletRequest request,
                    ServletResponse response)
             throws ServletException,
                    java.io.IOException

Frontend for calling service(HttpServletRequest,HttpServletResponse).

This method tries to typecast the ServletRequest and the ServletResponse to HttpServletRequest and HttpServletResponse and then call service(HttpServletRequest,HttpServletResponse).

Parameters:

request - The client's request

response - The class to write the response date to.

Throws:

ServletException - an error has occured

java.io.IOException - an error has occured

Overrides:

service in class GenericServlet

Since:

Servlet API 1.0