Sending a variable from Servlet to JSP

Question

I got a question about servlets and jsp.

Servlet:

public class Servlet extends javax.servlet.http.HttpServlet {

    protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
        Integer i = new Integer(15);
        request.setAttribute("var", i);
        RequestDispatcher Dispatcher = getServletContext().getRequestDispatcher("/index.jsp");
        Dispatcher.forward(request, response);
    }

JSP page:

<html>
  <head>
    <title></title>
  </head>
  <body>
        <form id="id" method="get" action="servlet">
            <%= (request.getAttribute("var")) %>
        </form>
  </body>
</html>

As a result I expect to see 15, but I see null. Why does it happen?

Are both the servlet and the JSP contained in the same application (WAR, project...)? — david a., Feb 24 '14 at 16:07
how ur accessing that index.jsp ...In web.xml u have a entry like this index.jsp..Isn't it @user2246018? — Naren, Feb 24 '14 at 16:53
I am almost sure ...your not giving chance to application for complete request-response cycle... u should access servlet first then only u can see that 15 on index.jsp other wise it will show you NULL definitely — Naren, Feb 24 '14 at 17:04

score 5 · Accepted Answer · edited May 23 '17 at 11:43

Request parameters are sent from the view to the controller, request attributes are used to pass data in the current request to help build the new response. So, you should not use scriplets and access to the request attributes by using Expression Language:

<body>
    <!-- No need to use a form for this page -->
    The request attribute: ${var}
</body>

Note that by your current request, you should perform a GET request on your servlet. Since your servlet name is servlet (which I suggest your to change it immediately), you should access to this URL: http://yourServerName/yourApplicationName/servlet

Good suggestions all around. – Sotirios Delimanolis Feb 24 '14 at 16:02 — Sotirios Delimanolis, Feb 24 '14 at 16:02

score 0 · Answer 2 · answered Feb 24 '14 at 15:59

0

Use request.getAttribute("var");

answered Feb 24 '14 at 15:59

AzAh

41
1
1
14

I fixed it. And I still see "null" – Green Fireman Feb 24 '14 at 16:00
May be surrounding brackets is the problem...cant check right now. Btw I would prefer Luiggi solution ;) – AzAh Feb 24 '14 at 16:14

score 0 · Answer 3 · answered Feb 26 '14 at 21:55

I don't know in the servlet but in struts 2 you need getter and setter method to sent data from jsp, you try this:

public class Servlet extends javax.servlet.http.HttpServlet 
{
    private Integer i;
    protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
        i = new Integer(15);
        request.setAttribute("var", i);
        RequestDispatcher Dispatcher = getServletContext().getRequestDispatcher("/index.jsp");
        Dispatcher.forward(request, response);
    }

  public Integer getI()
  {
     return i;
  }
  public void setI(Integer i)
  {
    this.i = i;
   }

 }//also lacked this

Sending a variable from Servlet to JSP

3 Answers3

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