[Okta Webinar] Learn how to a build a cloud-first strategyRegister Now

x
?
Solved

jsp:forward ?

Posted on 2006-06-21
10
Medium Priority
?
368 Views
Last Modified: 2010-04-01
Hi,
I'm new to JSP
I code a simple game in JSP,
where the user has to guess a number between 0 and 9

if he wins, he gets a congrats message, if he looses, another message is displayed.
If he wins OR loses, the statistics (number games played, ...) are displayed. So I have this code :

if user wins
   display "congrats" message
   display stats
else
   display "u lose" message
   display stats

I read in a book that I need , after displaying the messages, use
<jsp:forward page = stats.jsp"/>
to display the statistics because it is common code and better for refactoring.
(its just an educational example)
So I tried to use the forward:jsp action but I lose the messages 'congrats' and 'u lose'

<html>
  <head>
    <title>Jeu de devinette</title>
  </head>
  <body>
    <h3>Jeu de devinette</h3>
    <hr/>

<%// récupération de la partie en cours, au besoin création et rangement d'une nouvelle partie

  jeu.JeuDeDevinette jeu
              = (jeu.JeuDeDevinette)session.getAttribute("jeu");
  if (jeu == null) {
      jeu = new jeu.JeuDeDevinette();
      session.setAttribute("jeu", jeu);
  }

   String essai = request.getParameter("essai");
   out.print("ESSAIIII "+essai+"<br/>");
  // si l'utilisateur arrive pour la premiere fois sur la page, il n'a pas encore fourni de valeur
  if (essai != null) {
      jeu.setEssai(essai);
  }

  if (jeu.isGagne()) {
      out.println("Bravo, vous avez gagn&eacute;<br/>");
      out.println("<a href='jeu.jsp'>Rejouer</a>");
      // si l'utilisateur revient sur la page, il doit commencer automatiquement une nouvelle partie
      session.removeAttribute("jeu");
  %>
  <jsp:forward page="stat.jsp"/>
  <%
  }
  else if (jeu.getNombreDEssaisRestant() == 0) {
            out.println("D&eacute;sol&eacute;, vous avez perdu<br/>");
        out.print("Il fallait trouver ");
        out.println(jeu.getValeur());
        out.println("<br/><a href='jeu.jsp'>Rejouer</a>");
        // si l'utilisateur revient sur la page, il doit commencer automatiquement une nouvelle partie
        session.removeAttribute("jeu");
  }
  else {  // partie en cours, on n'a pas gagné ni perdu
      out.print("Il vous reste ");
      out.print(jeu.getNombreDEssaisRestant());
      out.println(" essai(s)<br/>");
      out.println("<form>");
      out.println("  essai : <input type='text' name='essai'/><br/>");
      out.println("  <input type='submit' value='Essayer'/>");
      out.println("</form>");

      // on triche en affichant la valeur à  trouver, pour faciliter les tests
      out.println(jeu.getValeur());
  }
%>

</body>
</html>

0
Comment
Question by:matthew016
  • 4
  • 3
  • 2
  • +1
10 Comments
 
LVL 23

Accepted Solution

by:
Siva Prasanna Kumar earned 1000 total points
ID: 16953210
if you want to show both Message as well as stats use <jsp:include page="stat.jsp"/> instead of
<jsp:forward page="stat.jsp"/>

Thank You.

0
 
LVL 3

Assisted Solution

by:runa_paathak
runa_paathak earned 600 total points
ID: 16957308
Else if you want to use <jsp:forward page = stats.jsp"/>, add the message string into request (request.setAttribute("msg"), msg) and then do <jsp:forward page = stats.jsp"/>. Display the message itself on stats.jsp by doing out.println(request.getAttribute("msg"))

Hope this helps.
0
 
LVL 9

Author Comment

by:matthew016
ID: 16962381
Thank u,
What is the real use of jsp:forward then ?
Thx
0
Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

 
LVL 4

Assisted Solution

by:evnafets
evnafets earned 400 total points
ID: 16964216
You use a jsp:forward, when you want to cancel the current page and display a different one.
A jsp:include, includes the RESULT of invoking the url specified into the current page, at the current point.

0
 
LVL 23

Expert Comment

by:Siva Prasanna Kumar
ID: 16965750
Actuattly jsp:forward is very useful when you want to navigate from one JSP to another.
and when you say include it jsp:includes the secified JSP to the current JSP at runtime.

check out for better details

http://java.sun.com/products/jsp/tags/11/syntaxref11.fm9.html 
0
 
LVL 9

Author Comment

by:matthew016
ID: 16968614
isn't this already possible with html to navigate trough pages ?
why use jsp:forward and not an html request
0
 
LVL 23

Expert Comment

by:Siva Prasanna Kumar
ID: 16969579
what if you want to pass some active stuff between the pages??? and how will you maintain the sessions??? Lot many other reasons are there.
0
 
LVL 9

Author Comment

by:matthew016
ID: 16969645
Thank you :-)
0
 
LVL 4

Expert Comment

by:evnafets
ID: 16976994
A forward/include is different from HTML navigating the page, because it is all done in the same HTTP request.
To the client browser, all of the forwards/includes are invisible.
All it knows is it requested a url - eg stat.jsp

To build stat.jsp the server might use header.jsp, footer.jsp, statHeader.jsp and queryResults.jsp to make the final page - but the client knows nothing about it - all it knows is "stat.jsp" was requested, and it got back some HTML.

Forward lets you change your mind about which page to display, include lets you use a template multiple times in your site, without writing it every time.

0
 
LVL 9

Author Comment

by:matthew016
ID: 16977045
Thanks for the additional info .
0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This shares a stored procedure to retrieve permissions for a given user on the current database or across all databases on a server.
Applications for our next round of the Experts Exchange Scholarship Contest are starting to roll in. It made us wonder what our past winners are up to these days. Here's a look at what four winners experienced with the contest and what they're doing…
Exchange organizations may use the Journaling Agent of the Transport Service to archive messages going through Exchange. However, if the Transport Service is integrated with some email content management application (such as an anti-spam), the admin…
Is your OST file inaccessible, Need to transfer OST file from one computer to another? Want to convert OST file to PST? If the answer to any of the above question is yes, then look no further. With the help of Stellar OST to PST Converter, you can e…
Suggested Courses

872 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question