Prentice Hall and Sun Microsystems. Personal use only; do not redistribute.

96

Chapter 4 Handling the Client Request: HTTP Request Headers

should usually check 

getProtocol

 before specifying response 

headers (Chapter 7) that are specific to HTTP 1.1.

4.2 Printing All Headers

Listing 4.1 shows a servlet that simply creates a table of all the headers it

receives, along with their associated values. It also prints out the three com 

ponents of the main request line (method, URI, and protocol). Figures 4 1

and 4 2 show typical results with Netscape and Internet Explorer. 

Listing 4.1 ShowRequestHeaders.java 

package coreservlets;

import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

import java.util.*;

/** Shows all the request headers sent on this

 *  particular request.

*/

public class ShowRequestHeaders extends HttpServlet {

  public void doGet(HttpServletRequest request,

                    HttpServletResponse response)

      throws ServletException, IOException {

    response.setContentType("text/html");

    PrintWriter out = response.getWriter();

    String title = "Servlet Example: Showing Request Headers";

    out.println(ServletUtilities.headWithTitle(title) +

                "\n" +

                "
" + title + "
\n" +

                "Request Method: " +

                request.getMethod() + "
\n" +

                "Request URI: " +

                request.getRequestURI() + "
\n" +

                "Request Protocol: " +

                request.getProtocol() + "

\n" +

Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.

Servlet and JSP training courses by book's author: courses.coreservlets.com.