Jsp and javabean

[Rohini thacker]

Hi all,
here are the steps :
. trying to populate javabean in servlet
. put that bean object in session using setAttribute
. pass control from servlet to jsp using
sendredirect
. in JSp using usebean tag I am trying to
access bean using session scopt but in jsp it is not showing me any data
. in servlet it is showing one record but in
jsp 0
I have tried same thing using requestdispatcher also. but same problem. I am trying to execute the code using visual age webshpere test enviroment.
Please help.
Thanks
Rohini

[Jessica Sant]

maybe you're losing the session between pages??
try printing out the Session ID on both pages -- are they different? if yes -- then make sure your browser accepts cookies. Or better yet... encode all your URLs with response.encodeURL() -- if cookies are disabled, it will automatically append the SessionID to the URL.

[Philip Shanks]

I doubt if the session is getting broken. I think the approach is fine, right up until the redirect. I suspect that a forward() is more appropriate here.
With a redirect, you don't passing control of the request, you create a new request (there is another round trip to the client and back).
But then, I could be wrong

[Geeta Ramasami]

Hi,
As the session is associated with the request object, if u use sendRedirect the request won't be available so if u try accesing the bean in session scope the values would be null.So use forward to forward the request and get the values from the session object.
Hope this helps
Cheers
Geeta

[Rohini thacker]

Hi Everyone,
I have tried same code using Forward() also. but same thing.
Please help.
Thanks
Rohini

[Rohini thacker]

hi everyone,
I have checked session id in servlet and jsp both are different.
what should I do now?
Rohini

[Chad McGowan]

Does the jsp you are forwarding to reside in the same application?

[suresh guru]

hi
It seems the useBean creates a new session. Pls retrieve the bean using scriplet<% %> and try to access the properties

[Rohini thacker]

Hi All,
here is my code.
I am using Visual Age for java's WTe to test the code.
my jsp is residing under
c:/ibm/VisualAge for Java\ide\project_resources\IBM WebSphere Test Environment\hosts\default_host\default_app\web\jsp\
and my servlet and bean are under shop packages.
I have include this in class path setting of websphere test environment.
is there any problem with my code or do I need to reinstall VAJ.
Please help
Rohini

  Shop Controller servlet
package shop;
/**
 * Insert the type's description here.
 * Creation date: (4/4/2003 7:08:18 AM)
 * @author: Administrator
 */
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class ShopController extends HttpServlet {
Connection con;

public void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, java.io.IOException {
performTask(request, response);
}
/**
 * Process incoming HTTP POST requests 
 * 
 * @param request Object that encapsulates the request to the servlet 
 * @param response Object that encapsulates the response from the servlet
 */
public void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, java.io.IOException {
performTask(request, response);
}
/**
 * Initializes the servlet.
 */
public void init() {
// insert code to initialize the servlet here
try{
Class.forName("COM.ibm.db2.jdbc.app.DB2Driver");
}
catch( ClassNotFoundException e2)
     {
      System.out.println("\nJDBC Driver class not found exception");
     }
     catch( Exception e)
     {
       System.out.println("\nDriver class not found exception");
    }


//con = DriverManager.getConnection();


}
public void performTask(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) {
ResultSet rs = null;
HttpSession session1 = request.getSession(true);
/*if (session == null) {
ServletContext sce = getServletContext();
response.sendRedirect(Localhost + "/Template/Logout.jsp");
}*/
//Vector prodlist = new Vector();
try{
con = DriverManager.getConnection("jdbc :mrgreen: b2:SHOP","","");
Statement stmt = con.createStatement();
rs = stmt.executeQuery("SELECT * from product");
System.out.println("Received results:");
       /* while (rs.next()) {
            String a = rs.getString(1);
            String str = rs.getString(2);
            System.out.print(" id= " + a);
            System.out.print(" product = " + str);
            System.out.print("\n");
        }
        rs.close();
        stmt.close();
        con.close();*/
        ProductListBean ProductListBean = new ProductListBean();
        ProductBean ProductBean = new ProductBean();
       // rs = prodinfo.getProductList();
        int j = 0;
        while (rs.next()) {
            int a = rs.getInt(1);
            String str = rs.getString(2);
            System.out.print(" id= " + a);
            System.out.print(" product = " + str);
            System.out.print("\n");
            
           // ProductListBean.add();
//ProductListBean.elementAt(j).setProductId(rs.getInt(1));
//ProductListBean.elementAt(j).setProductName(rs.getString(2));
//ProductListBean.elementAt(j).setProdDescription(rs.getString(3));
ProductBean.setProductId(rs.getInt(1));
 System.out.println(" Prod id : "+rs.getString(1));
 System.out.println(" Prod name : "+rs.getString(2));
ProductBean.setProductName(rs.getString(2));
 System.out.println(" Prod Description : "+rs.getString(3));
ProductBean.setProdDescription(rs.getString(3));
j++;
        }
        rs.close();
        stmt.close();
        con.close();
        System.out.println("No of  results:" + ProductListBean.getLength());
        // session.setAttribute("ProductListBean",ProductListBean);
        String str1 = "hi";
        session1.setAttribute("ProductBean",str1);
        //ProductBean ProductBean1;
        //ProductBean1 = (ProductBean) session1.getAttribute("ProductBean");
        //System.out.println(" Prod Id : "+ProductBean1.getProductId());
        //System.out.println(" Prod name : "+ProductBean1.getProductName());
        //System.out.println(" **************************************");
       // System.out.println("session1 : "+session1);
         RequestDispatcher rd = request.getRequestDispatcher("/jsp/test1.jsp");
         rd.forward(request,response);
        //response.sendRedirect("http://localhost:8080/jsp/test1.jsp");
}
catch(SQLException se){
System.out.println("error1");
}
catch(Exception e){
System.out.println("error2");
System.out.println(e.getClass().getName());
System.out.println(e.getMessage());
}
}
}

  Here is javabean
package shop;
/**
 * Insert the type's description here.
 * Creation date: (4/17/2003 2:38:10 PM)
 * @author: Administrator
 */
public class ProductBean implements java.io.Serializable {
private int prodid;
private String prodname;
private String proddsc;

/**
 * ProductBean constructor comment.
 */
public ProductBean() {
super();
}
public String getProdDescription(){
return this.proddsc;
}
public int getProductId() {
return this.prodid;
}
/**
 * Insert the method's description here.
 * Creation date: (4/17/2003 2:38:56 PM)
 * @return java.lang.String
 */
public String getProductName() {
return this.prodname;
}
public void setProdDescription(String str){
this.proddsc = str;
}
public void setProductId(int id) {
this.prodid = id;
}
public void setProductName(String str) {
this.prodname = str;
}
}

  here is test1.jsp
<%@ page import="shop.ProductBean session="true"%>
<jsp:useBean id="productbean"  class="shop.ProductBean"  scope="session"></jsp:useBean>
<html>
<head>
</head>
<body>

Prod Name :  <%=productbean.getProductName() %>
       Prod desc :  <%=productbean.getProdDescription() %>

</body>
</html>

[Pravin Panicker]

Try accessing your bean in request scope within the jsp and use request.setAttribute within the servlet. It should work.

[Ani joshi]

Hello Rohini,
In controller, I couldnt see the code where u saved productbean object in the session.
I can see only one line which is session1.setAttribute("ProductBean",str1);
I suppose , u want to save your productbean object in the session.
On which line you performed above task?
Regards
Anirudha

[suresh guru]

Hi
you are putting only str in session not the bean so the bean wont be available in the jsp.
String str1 = "hi";
session1.setAttribute("ProductBean",str1);
insted use
String str1 = "hi";
session1.setAttribute("ProductBean",ProductBean);
that will solve the problm i think

[Rohini thacker]

hello everyone,
The actual code was like this
session1.setAttribute("ProductBean",ProductBean);
System.out.println("session1 : "+session1);
RequestDispatcher rd = request.getRequestDispatcher("/jsp/test1.jsp");
rd.forward(request,response);

Sorry for the trouble.'
Regards,
Rohini

[suresh guru]

try to get the bean using <% %> tags in jsp insted of useBean, If it works, the problem is with useBean creating nes session, otherwise try simple res.sendRedirect("jsp-page"). while redirecting dont give http://localhost:8080 (I think it creates the problem insted use relative path /jsp/test1.jsp) & try to get the bean. Otherwise check the session timeout property of the server which u r using
hope this helps

[Hugh Jamieson]

A few observations that might help:
Based on your replys, it seems evident that your application is not correctly handling the session. Since you state that the session IDs are different between the servlet & the jsp, this means that the host is tracking these as 2 seperate sessions.
Also, when you getSession() from the request object, you are specifying (TRUE), which means that if the session does not exist, a new one will be created. You might change this to FALSE, and then uncomment the test to check for a NULL session. You may find that a session has not been created.
In addition, the <useBean> tag will create a new instance of a bean if it cannot find one in the scope requested. This makes it pretty difficult to tell how it got created unless you put some signature in the bean to indicate how it was instantiated.
I have run into this issue before with Tomcat & IE. For some reason, the session cookie does not flow back to the server when you initiate the session. I used the debug options of IE to prompt me anytime a cookie was exchanged, and I found that the beginning of the session was NOT sending the start-session cookie when I expected it. I also posted this on the forum, but didn't find anything that really fixed it.
However, I did find something that had more than a causal effect: The hostname. Most of us use http://localhost:8080/... to develop. In this environment, everything worked GREAT. But, as sooon as my URL used a hostname, i.e. http://bigserver:8080/... , this silly session thing got in my face. If I simply replaced the hostname with the hosts IP address, the problem dissapeared!
I have come to the conclusion (and I could be smoking dope) that this is a DNS issue. I know the server is doing host lookups during http traffic, so I think this is plausable.
Anyway, try your code again, but this time, use the IP address. See what happens.
Hugh

[Rohini thacker]

Hi All,
As per rgsuresh suggestion, I have tried to get the bean using <% %> tags in jsp insted of useBean, and it worked.
this is my test1.jsp code

  
<%@ page import="shop.ProductBean"%>
<% 
ProductBean bean = null;
synchronized(session)
{
bean = (ProductBean) session.getAttribute("ProductBean");
if(bean==null)
{%>
bean is null
<%}
else
{
%>
 Prod id:  <%=bean.getProductId() %>
       Prod desc :  <%=bean.getProdDescription() %>
<% }
}
%>

Now can any body please explain me why Usebean is not working in my case?
Thanks
Rohini

[suresh guru]

Hi rohini
As of the code which u produced, I am also curious to know why it doesnt worked. But i think u must use the form <useBean/> insted of closing </useBean> and remove session="true" (as the default is true. try and if u find the correct tinng post the results here as i am also wondering the weired behaviour of useBean tag

[Rohini thacker]

Hi Everyone,
my problem is got solved now.
I have just come to know one thing
The attribute name that u have used to store oject in session, you have to use same attribute name in JSP:usebean tag to access it.

I will explain this using below code
In servlet
ProductBean ProductBean = new ProductBean();
// populate bean with data
session1.setAttribute("ProductBean",ProductBean);
Now is Jsp u should right following code to access bean.
<jsp:useBean id="ProductBean" class="shop.ProductBean" scope="session"> </jsp:useBean>
That means whatever value u put in id should be same as setattribute.
Regards
Rohini