Authenticate and fetch data

Question

I suppose scores of people have asked this question; and even after reading most of those threads, I still haven't been completely successful.
Here's my query:
I'm trying to write an application that opens an HttpURLConnection, fills the login and password on a form, and upon submitting the form, the server returns a data(.exe) file which has to be fetched.
My code pasted below works on my own company's website (i.e. authenticates me and fetches the redirected html page content after that).
However the site for which the application is meant for, returns the same initial logon page after execution, instead of the .exe file.
Here's my code:
===========================================================
package authhttpdatadownload;
import java.io.*;
import java.net.*;
import java.nio.charset.CharsetEncoder;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class AuthHTTPDataDownload {   
    public static void main(String[] args) {
       String localFilePath = new String("C:/Temp/0929.exe");
       String urlHost = new String("http://www.somesite.com");
       String urlUserName = new String("user1");
       String pwd = new String("pass1");
       String urlPath = new String("http://www.somesite.com//logon.aspx?ReturnUrl=%2fdata%2f0929.exe");
        try {
            String postData="txtUserName="+URLEncoder.encode(urlUserName,"UTF-8");
            postData+="&"+"password="+URLEncoder.encode(pwd,"UTF-8");
            FileOutputStream fos = new FileOutputStream(localFilePath);
            DataOutputStream dos = new DataOutputStream(new FileOutputStream(localFilePath));
            URL url = new URL(urlPath);
            HttpURLConnection huc = (HttpURLConnection) url.openConnection();
            huc.setDoInput(true);
            huc.setDoOutput(true);
            huc.setUseCaches (false);
            huc.setRequestMethod("POST");
            huc.setFollowRedirects(true);
            OutputStreamWriter osw = new OutputStreamWriter(new BufferedOutputStream(huc.getOutputStream()));
            osw.write(postData);
            osw.flush();
            osw.close();
            BufferedReader buffer = new BufferedReader(new InputStreamReader(huc.getInputStream()));
            String idata;
            while ((idata=buffer.readLine()) != null) {
                dos.writeBytes(idata);
            buffer.close();
            dos.close();
            fos.close();
            huc.disconnect();
        catch (Exception ex) {
            System.out.println("Exception - " + ex.getMessage());
}==========================================================
Here's the relevant part of the form on the logon page:
<form name="frmLogon" method="post" action="logon.aspx?ReturnUrl=%2fdata%2f0929.exe" id="frmLogon">
<input type="hidden" name="__VIEWSTATE" value="dDwxMzEyNjgwNzE0Ozs+8RfeXl1eee5WsfphofQJZlmlIDc=" />
               <table WIDTH="90%" cellpadding="0" cellpadding="0" border="0">
                    <tr>
                         <td>
                              <h1>Login</h1>
                              <table>
                                   <tr>
                                        <td Width="110px" align="left">
                                             <span id="lblUserName">User Name : </span>
                                        </td>
                                        <td width="260px" align="center">
                                             <input name="txtUserName" type="text" id="txtUserName" />
                                        </td>
                                   </tr>
                                   <tr>
                                        <td Width="110px" align="left">
                                             <span id="lblPassword">Password :</span>
                                        </td>
                                        <td width="260px" align="center">
                                             <input name="txtPassword" type="password" id="txtPassword" />
                                        </td>
                                   </tr>
                                   <tr>
                                        <td Width="110px" align="left">
                                        </td>
                                        <td width="260px" align="center" valign="middle" height="32px">
                                             <input type="submit" name="btnLogon" value="Log On" id="btnLogon" />
                                        </td>
                                   </tr>
                                   <tr>
                                        <td colspan="2" align="center">
                                             <span id="lblError"><font color="Red"></font></span>
                                        </td>
                                   </tr>
                              </table>===================================================
what I've noticed is a hidden input field on the form what looks like a randomly-generated value by the server on this form. Is this the reason why my program cannot authenticate to the server in this case?(in the other case where it works, the form doesn't have a hidden field) If yes, then given the form above, how could this be achieved? Any suggessions would be much appreciated.
Thanks!
-nitin
===================================================

Answer 1

If you have a model and needs to refresh the data, do not reinstantiate the model with new data. Add a set method to your model as such:
public void setData(Object data)
  // Set internal variables as necessary
fireTableDataChanged();
}Otherwise, you have new objects being created, the table has to readjust its listeners, etc. That's extra overhead that is not necessary.