public void registrarUsuario() {
    String dato = "";
    JSONParser parser = new JSONParser();
    try {
      while (true) {
        dato = dis.readUTF();
        String usuario = "";
        String contraseña = "";
        String contra = "";
        if (dato.equals("Usuario")) {
          while (true) {
            usuario = dis.readUTF();
            if (usuario != null) {
              JSONObject user = new JSONObject();
              user.put(usuario, null);
              FileWriter escribir = new FileWriter("texto.txt");
              BufferedWriter bw = new BufferedWriter(escribir);
              PrintWriter pw = new PrintWriter(bw);
              pw.write(user.toJSONString());
              pw.close();
              bw.close();
              while (true) {
                contra = dis.readUTF();
                if (contra.equals("Contraseña")) {
                  while (true) {
                    contraseña = dis.readUTF();
                    if (contraseña != null) {
                      Object obj = parser.parse(new FileReader("texto.txt"));
                      JSONObject asignaPass = (JSONObject) obj;
                      asignaPass.put(usuario, contra);
                      FileWriter escribir2 = new FileWriter("texto.txt");
                      BufferedWriter bw2 = new BufferedWriter(escribir2);
                      PrintWriter pw2 = new PrintWriter(bw2);
                      pw2.write(asignaPass.toJSONString());
                      bw2.newLine();
                      pw2.close();
                      bw2.close();
                      break;
                    }
                  }
                  break;
                }
              }
              break;
            }
          }
          break;
        }
      }
    } catch (Exception e) {

    }
  }
 /** @see Servlet#service(ServletRequest request, ServletResponse response) */
 public void service(ServletRequest request, ServletResponse response)
     throws ServletException, IOException {
   // TODO Auto-generated method stub
   String input_string = request.getParameter("text");
   PrintWriter out = response.getWriter();
   Query parsed_query = parse(input_string);
   // Wrong input format -> null returned in parse function
   if (parsed_query == null) {
     String message = "Unknown query format";
     out.write(message.toCharArray());
   }
   // correct input format
   else {
     String answer = handleQuery(parsed_query);
     out.write(answer);
   }
 }