IllegalStateException problem...

Question

Hi, I have a problem with a jsp application. I have a form which I use to access to a secured area. To login I send to a servlet the username and the password but the result is this error:
java.lang.IllegalStateException
     org.apache.catalina.connector.ResponseFacade.sendRedirect(ResponseFacade.java:435)
     UnicolorController.doGet(UnicolorController.java:119)
     UnicolorController.doPost(UnicolorController.java:127)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
     javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
the code responsable of this is the following (a little piece from doGet(HttpServletRequest req, HttpServletResponse res) method)
        else if (action.equals("private") ) {
            HttpSession sessione = req.getSession(true);
            if (sessione.getAttribute("unicolor.utente") != null ) {
                Utente utente = (Utente)sessione.getAttribute("unicolor.utente");
                String p = utente.getPrivilegi();
                if (p.equals("admin")) {
                    res.sendRedirect("../admin_panel.jsp");
                } // else ... qua va inserito il codice nel caso ci siano utenti
                  // non admin ad effettuare l'accesso.
            } else {
                String user = req.getParameter("username");
                String pass = req.getParameter("password");
              //controlli
                if (user == null) user="";
                if (pass == null) pass="";
                String privilegi = null;
                try {
                    if (!DBInterface.driverLoad())
                        res.sendRedirect("../errore.jsp");
                    else {
                        Connection c = DBInterface.connect();
                        Statement s = c.createStatement();
                        ResultSet r = s.executeQuery("SELECT privilegi FROM utenti "+
                              "WHERE user=\'"+DBInterface.codificaApici(user)+
                              "\' AND password=\'"+DBInterface.codificaApici(pass)+"\'");
                        if (r.next())
                            privilegi = r.getString("privilegi");
                        else
                            res.sendRedirect("../privato.jsp");
                        r.close();
                        s.close();
                        c.close();
                } catch (SQLException e) {
                    res.sendRedirect("../errore.jsp");
                if (privilegi != null) {
                    //controllo i privilegi in base ai quali accedo alla sezione
                    Utente u = new Utente(user,pass,privilegi);
                    sessione.setAttribute("unicolor.utente", u);
                    if (privilegi.equals("admin"))
                            res.sendRedirect("admin_panel.jsp");
                    //else... per utenti non admin
                } else  if (user.length() > 0)
                            res.sendRedirect("../login_fallito.jsp");
                        else
                            res.sendRedirect("../privato.jsp");
[...]I overrided the method doPost by calling doGet in it and passing the same parameters...
The code in the JSP page is the following:
                    <form id="access" name="privato" method="post" action="servlet/controller?act=private" >
                        <table align="center">
                          <tr>
                            <td class="stile_form">Username:</td>
                            <td class="stile_form"><input name="username" type="text" size="20" maxlength="20" /></td>
                          </tr>
                          <tr>
                            <td class="stile_form">Password:</td>
                            <td class="stile_form"><input name="password" type="password" size="20" maxlength="20" /></td>
                          </tr>
                        </table>
                        <label>
                            <input type="submit" name="button" id="button" value="Accedi" />
                        </label>
                    </form>Anybody can help me?
thanks in advance

Answer 1

Well you've got a line number to work from. Which one of those is line 119 of the doGet method?
The only way to figure it out I think will be to trace it through.
I have one suggestion that might make it easier to follow though.
Have only ONE sendRedirect in your method.
Replace the other ones with setting a variable, and then use that variable in your redirect at the end of your method.
ie
String nextPageToGoTo == SUCCESS_PAGE;
if (somethingWrong){
  nextPageToGoTo = ERROR_PAGE;
response.sendRedirect(nextPageToGoTo);Its a medium sized change to the code, but it should make it easier to trace, and prevent double redirects.