JSP and send object

Question

I have problém with send servlet to JSP

I have "web.xml".

    <servlet>
    <description></description>
    <display-name>optimalizace5</display-name>
    <servlet-name>optimalizace5</servlet-name>
    <servlet-class>
BucketServlet2
 </servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>optimalizace5</servlet-name>
    <url-pattern>/optimalizace5</url-pattern>
  </servlet-mapping>

and BucketServlet2:

public class BucketServlet2 extends HttpServlet{

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse resp)
        throws ServletException, IOException {

     request.getSession().setAttribute("vysledek_list", "10101101");
     getServletContext().getRequestDispatcher("/optimalizace4.jsp").forward(request, resp); 
     super.doPost(request, resp);
    }
}

and JSP:

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Optimalizační úlohy</title>
</head>
<body>
<FORM action="/Eliminace_kosiku/optimalizace5" method="post">

Data:

<%=request.getParameter("vysledek_list")%>

</form>
</body>
</html>

For send from JSP to servlet is working. But send from servlet to JSP not working. I dont know, what is wrong??

Plz, specify your question. `from servlet to JSP not working` is ambiguous. — Masudul, Apr 06 '15 at 11:10
<%=request.getParameter("vysledek_list")%> return null. And return must be "10101101". — user3640712, Apr 06 '15 at 11:23

score 1 · Answer 1 · edited May 23 '17 at 12:06

You are putting value in session, not in request object.

request.getSession().setAttribute("vysledek_list", "10101101");
//          ^ setting attribute in session object.

So you need to take out value from session object in jsp.

Session is implicit object in jsp, so you can directly use it like

<%=session.getAttribute("vysledek_list")%>

Note: Don't forget to remove it from session if you don't need it further.

<%session.removeAttribute("vysledek_list");%>

Another approach: With reference to this.

You can just change below line in your code of doPost method

request.getSession().setAttribute("vysledek_list", "10101101");

with

request.setAttribute("vysledek_list", "10101101");

Update : Addition in second approach, in jsp use getAttribute method instead of getParameter method.

<%=request.getAttribute("vysledek_list")%>

I am try it, but still is variable null. – user3640712 Apr 06 '15 at 14:28 — user3640712, Apr 06 '15 at 14:28
Did you try both approach? – Naman Gala Apr 06 '15 at 15:22 — Naman Gala, Apr 06 '15 at 15:22

Masudul · Accepted Answer · 2015-04-06T11:33:50.267

0

getParameter take the URL parameter value. At Servlet you set the value at session, so, you should use session.getAttribute instead of getParameter

<%=request.getSesstion().getAttribute("vysledek_list")%>

Another point, As you use forward method at Servlet so request.setAttribute enough to pass value to JSP page. You should not store temporary value(i.e. same request) at session. So, set the value at request instead of session like below.

 request.setAttribute("vysledek_list", "10101101");

edited Apr 06 '15 at 11:33

answered Apr 06 '15 at 11:25

Masudul

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I cant. "Vote up requires 15 reputation" :( – user3640712 Apr 07 '15 at 09:59
@user3640712, there is a check mark below the down-vote arrow, you can click on it. – Naman Gala Apr 07 '15 at 10:38

JSP and send object

2 Answers2