Thursday, 17 July 2014

doHead (HttpServletRequest req, HttpServletResponse resp)

protected void doHead(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
The HEAD method is identical to GET except that the server MUST NOT return a message-body in the response. Receives an HTTP HEAD request from the protected service method and handles the request.

The client sends a HEAD request when it wants to see only the headers of a response, such as document size, modification-time, Content-Type or Content-Length. The HTTP HEAD method counts the output bytes in the response to set the Content-Length header accurately. DoGet method automatically supports HEAD request also.

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
   
     <title>Filter Example</title>
    </head>
    <body>
        <form method="head" action="/servlet/HelloWorld">
            <input type="submit" value ="Get Header">
        </form>
    </body>
</html>

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
       
@WebServlet(urlPatterns="/HelloWorld")
public class HelloWorld extends HttpServlet {
    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException{
       try(PrintWriter out = res.getWriter()) {
            res.setContentType("text/html");
            System.out.println("I am here");
            String str = "<html>" +
                         "<head>" +
                         "<title> Hello World </title>" +
                         "</head>" +
                         "<body><h1> Hello World" +
                         "</h1> </body>" +
                         "</html>";
            out.println(str);
       }
   } 
  
}

@WebServlet Annotation used to declare a servlet. This annotation is processed by the container at deployment time, and the corresponding servlet made available at the specified URL patterns.



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