Strange behaviour with response.sendRedirect

Question

I have a strange problem with response.sendRedirect
--The following is part of a class that implements Filter (its main task is to check for authentication)
The redirect method hresponse.sendRedirect doesnot work (so i had to make it a forward method using dispatcher)
The second one however, works!!!! how could that be?
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
      throws ServletException, IOException
           HttpServletRequest h =(HttpServletRequest)request;
           HttpServletResponse hresponse = (HttpServletResponse)response;
           ServletContext application = config.getServletContext();
        Connection con = (Connection)application.getAttribute("connection");
           String username = (String)h.getSession().getAttribute("user");
           String credentials = (String)h.getSession().getAttribute("cred");
           PrintWriter out = response.getWriter();
           if (con != null)
               try
               Statement     stmt = con.createStatement(
                    ResultSet.TYPE_SCROLL_INSENSITIVE,
                     ResultSet.CONCUR_READ_ONLY);
          ResultSet rs;
                    rs = stmt.executeQuery("SELECT * FROM member WHERE username = '"+ username
                                                                                          +"' AND password ='" + credentials+ "' ");
                    if(rs.next() && rs != null)
     String path = h.getServletPath() ;
          h.getSession().setAttribute("user", username);
          h.getSession().setAttribute("cred", credentials);
          //RequestDispatcher dispatcher = config.getServletContext().getRequestDispatcher(path);
//dispatcher.forward(request,response);
          String s = hresponse.encodeURL("http://localhost:8080/support/mtext.html");
               //out.println(s);
               hresponse.sendRedirect(s);
                    else
     String path = h.getRequestURI();
     String query = h.getQueryString();
//     String query_sub = query.substring(0,equalPos);
     if (!query_sub.equals("threadID"))
          out.println("error occured");
               else
          if(query == "null")
               query="";
          else
               query= "?" + query;
               hresponse.sendRedirect(hostPath + "/support/index2.jsp?"+
               "forward="+h.getRequestURI() + query );
               }

Answer 1

Hi,
response.sendRedirect() may throw an IOException if URL not found.So you have to write throws or try & catch.
Ajay.