Blank page while servlet to jsp.

Question

Hi.
am working in a code for login verification.
In my login database i have different user.For each user user access will be different.
So am verifying password for a particular user.The verification is done in servlet page .
After verification am viewing only a blank page.
Can u give me any suggestion.
my code is given below.
response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
         HttpSession session=request.getSession();
        String user="",pass="";
        //ServletContext context=null;
        ServletContext context=getServletContext();
String userName=request.getParameter("user").trim();
String passWord=request.getParameter("pass").trim();
        String query="select * from login where user='"+userName+"' ";
       String DbUserName="";
       String DbPassword="";
       String finalUser="";
       try {
             Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
             Connection con1=DriverManager.getConnection("jdbc:odbc:register");
              Statement stat=con1.createStatement();
              ResultSet rst=stat.executeQuery(query);
                while(rst.next())
     user=rst.getString("user");
pass=rst.getString("pass");
              if((userName.equalsIgnoreCase(user))&&(passWord.equalsIgnoreCase(pass)))
            session.setAttribute("user",user);
        context.getRequestDispatcher("/Mainmenu.jsp").forward(request,response);
        else
               context.getRequestDispatcher("/LoginError.jsp").forward(request,response);
catch(Exception e){
             e.printStackTrace();
      }Thanks in advance,
regards,
satheeshkannan

Answer 1

Indeed, you are just printing and ignoring the exception instead of throwing it or change the flow.
Apart from this problem: why are you comparing the username once again after the query while the query should only return rows matching the username? Anyway, if your DB is well-designed (i.e. username is unique), then you can also just query for rows matching the username and the password so that you just need to check if ResultSet#next() returns true or not.
Oh, don't forget to use PreparedStatement instead. It will save you from SQL injections.