Help : Servlet Service Method

Dear all,

I have one html page which calling a servlet. In this servlet service method is overridden. In form tag of html page method is either GET or POST. So after I click submit button in html page it calls servlet and servlet executes. So how this happens?

I am also giving code below

Test.html

<HTML>
<HEAD>
</HEAD>
<BODY>
<form name="e" method="POST" action="/servlet/TestServlet">
<INPUT TYPE="submit" value="Submit">
</form>
</BODY>
</HTML>

On submit it is calling TestServlet

package com.test.servlet;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class TestServlet extends HttpServlet
{
public void service(HttpServletRequest Req,HttpServletResponse Res)
{
try
{
PrintWriter out = Res.getWriter();
out.println("http://www.javaranch.com");
}
catch (Exception e)
{
e.printStackTrace();
}
}
}

How this service method written in servlet is identifying get or post method?

regards,
Amit Kulkarni
[ July 07, 2005: Message edited by: AmitVijay AVKulkarni ]

The defualt implementation of service method checks for the HTML form's method and it forward to GET and POst depending on method's type.But since your are overriding the service method, The new code will be executed insted of checking for method's type.
No errors, just works fine.

Here is the actual code of HttpServlet's service() method default implementation. request.getMethod() method is used to determine the type of method used by client browser while it invoked the service:

protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException
{
String method = req.getMethod();
 
if (method.equals(METHOD_GET)) {
    long lastModified = getLastModified(req);
    if (lastModified == -1) {
  // servlet doesn't support if-modified-since, no reason
  // to go through further expensive logic
  doGet(req, resp);
    } else {
  long ifModifiedSince = req.getDateHeader(HEADER_IFMODSINCE);
  if (ifModifiedSince < (lastModified / 1000 * 1000)) {
      // If the servlet mod time is later, call doGet()
                  // Round down to the nearest second for a proper compare
                  // A ifModifiedSince of -1 will always be less
      maybeSetLastModified(resp, lastModified);
      doGet(req, resp);
  } else {
      resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
  }
    }
 
} else if (method.equals(METHOD_HEAD)) {
    long lastModified = getLastModified(req);
    maybeSetLastModified(resp, lastModified);
    doHead(req, resp);
 
} else if (method.equals(METHOD_POST)) {
    doPost(req, resp);
    
} else if (method.equals(METHOD_PUT)) {
    doPut(req, resp);  
    
} else if (method.equals(METHOD_DELETE)) {
    doDelete(req, resp);
    
} else if (method.equals(METHOD_OPTIONS)) {
    doOptions(req,resp);
    
} else if (method.equals(METHOD_TRACE)) {
    doTrace(req,resp);
    
} else {
    //
    // Note that this means NO servlet supports whatever
    // method was requested, anywhere on this server.
    //
 
    String errMsg = lStrings.getString("http.method_not_implemented");
    Object[] errArgs = new Object[1];
    errArgs[0] = method;
    errMsg = MessageFormat.format(errMsg, errArgs);
    
    resp.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, errMsg);
}
}