CODEWITHSUNDEEP
javaservletscookies
Mladen Adamovic
Mladen Adamovic

Reputation: 3211

response.addCookie after something is written already to

    PrintWriter out = response.getWriter();
  out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">");
  out.println("<html>");
  out.println("<head>");
    Cookie offeredCommunityCookie = new Cookie("offered_community", "true");
    offeredCommunityCookie.setMaxAge(51840000); // 600 days
    response.addCookie(offeredCommunityCookie);

Will this cookie will be actually added to the response? Since cookies goes into header of the message as:

Cookie: NAME1=OPAQUE_STRING1; NAME2=OPAQUE_STRING2

Why Servlet container, if this doesn't work, do not display a warning or throws an exception?

Upvotes: 0

Views: 1988

Answers (1)

Mladen Adamovic
Mladen Adamovic

Reputation: 3211

As suspected, adding cookies seems not to be working as expected if you did writing to the response before it.

This is the servlet I run which, after execution, I don't see "test_cookies" as a cookie in my localhost using Chrome. Web servlet is Glassfish 4.1, but I guess it is a container-independent issue.

package common;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 *
 * @author mladen
 */
public class TestCookiesServlet extends HttpServlet {

  /**
   * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
   *
   * @param request servlet request
   * @param response servlet response
   * @throws ServletException if a servlet-specific error occurs
   * @throws IOException if an I/O error occurs
   */
  protected void processRequest(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out = response.getWriter();
    try {
      out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">");
      out.println("<html>");
      out.println("<head>");
      out.flush();
      response.flushBuffer();
      Cookie offeredCommunityCookie = new Cookie("test_cookies", "true");
      offeredCommunityCookie.setMaxAge(51840000); // 600 days
      response.addCookie(offeredCommunityCookie);
    } finally {
      out.println("</head>");
      out.println("<body>Test<p/>Test<p/>Test");
      out.println("</body>");

      out.println("</html>");
      out.close();
    }
  }

  // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
  /**
   * Handles the HTTP <code>GET</code> method.
   *
   * @param request servlet request
   * @param response servlet response
   * @throws ServletException if a servlet-specific error occurs
   * @throws IOException if an I/O error occurs
   */
  @Override
  protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
    processRequest(request, response);
  }

  /**
   * Handles the HTTP <code>POST</code> method.
   *
   * @param request servlet request
   * @param response servlet response
   * @throws ServletException if a servlet-specific error occurs
   * @throws IOException if an I/O error occurs
   */
  @Override
  protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
    processRequest(request, response);
  }

  /**
   * Returns a short description of the servlet.
   *
   * @return a String containing servlet description
   */
  @Override
  public String getServletInfo() {
    return "Short description";
  }// </editor-fold>

}

Upvotes: 1

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