Ragazzi mi rivolgo a tutti...se potete aiutatemi non capisco più che debbo fare...
Sto cercando di validare un form tramite json e ajax su un progetto jsp
Però non ottengo il response della XMLhttprequest.
Questa è la pagina del form:

codice:
<?xml version="1.0" encoding="ISO-8859-1" ?>
<%@page import="it.polito.elite.sistinf.newEl.RoleEnum"%>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<jsp:useBean id="newUserError" class="it.polito.elite.sistinf.msg.error.ErrMsg" scope="request"/>
<jsp:useBean id="newUserFormData" class="it.polito.elite.sistinf.newEl.NewUserFormData" scope="request"/>
<div class="newUser">
<% 
out.println("<script type=\"text/javascript\" src=\""+request.getContextPath()+"/modules/users/js/newUserAjax.js\"></script>");

%>
<h2>Nuovo Utente</h2>
<form method="post" action="<%= request.getContextPath() %>/modules/users/doNewUser.jsp" id="newUserForm" name="newUserForm">

<% if (!newUserFormData.isValid()) { %>
<fieldset>
<legend>New User</legend>
<ul>[*]<label for="cognome">Cognome:<input id="newUserInput" type="text" name="cognome" size="8" value="${newUserFormData.cognome}"/></label>
<div id="cognome"></div>[*]<label for="nome">Nome:<input id="newUserInput" type="text" name="nome" size="8" value="${newUserFormData.nome}" /></label>
<div id="nome"></div>[*]<label for="matricola">Matricola:<input id="newUserInput" type="text" name="matricola" size="8" value="${newUserFormData.matricola}"/></label>
<div id="matricola"></div>[*]<label for="username">Username:<input id="newUserInput" type="text" name="username" size="8" value="${newUserFormData.username}"/></label>
<div id="username"></div>[*]<label for="telefono">Telefono:<input id="newUserInput" type="text" name="telefono" size="8" value="${newUserFormData.telefono}"/></label>
<div id="telefono"></div>[*]<label for="email">Email:<input id="newUserInput" type="text" name="email" size="8" value="${newUserFormData.email}"/></label>
<div id="email"></div>[*]<label for="tipo">Tipo:</label><select id="newUserSelect" name="tipo">
<option value="<%=RoleEnum.amministratore.toString()%>">amministratore</option>
<option value="<%=RoleEnum.intermedio1.toString()%>">intermedio1</option>
<option value="<%=RoleEnum.intermedio2.toString()%>">intermedio2</option>
<option value="<%=RoleEnum.base.toString()%>">base</option>
</select>[*]<div class="newUserResponsabile"><label for="tipo">Responsabile:<select id="newUserResp" name="responsabile">
<option class="utenti"></option>
</select></label><div id="responsabile"></div></div>[*]<label><input type="submit" name="submit" value="Crea"/></label>[/list]
</fieldset>
<% } %>
</form>
</div>
Questo è il file javascript(con jquery già incluso)

codice:
$(document).ready(function()
{	
	$(".newUserResponsabile").hide();
	

	var size = 0;
	$("#newUserForm").submit(function(){doCheckForm();	});
	
	
	// attach click handler to the post button
	$("#newUserInput").blur(function(){doCheckInput();});

});

function doCheckInput()
{
	// get the value
	var input = $("#newUserInput").attr("name");
	
	var value = $("#newUserInput").val();
	// compose the ajax request
	var url = "ajaxNewUser";

	// call the get method via ajax...
	$.getJSON(
		url,
		{nome : input, valore : value},
		function (data){ changeInput(data); }
		);
	
}

function changeInput(data)
{
	
	alert(data);
	var nome = data.nome ;
	var valore = data.valore ;
	if (valore.substring(1,6)=="errore"){
		$(".newUserForm input[name$=nome]").css({'color':'#FF0000'});
		$("div.$nome").append(valore);
	}else{
		$("#newUserForm input[name$=nome]").attr("type","hidden");
		$("div#$nome").append(valore);
		size++;
	}
	
}

}
e questa è la servlet:

codice:
package it.polito.elite.sistinf.newEl;

import it.polito.elite.sistinf.msg.error.RegExp;

import java.io.IOException;
import java.util.regex.Pattern;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.json.simple.JSONObject;

/**
 * Servlet implementation class ajaxNewUser
 */
@WebServlet(name="ajaxNewUser",
			description="Servlet for new user form",
		urlPatterns = { "ajaxNewUser" })
public class ajaxNewUser extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public ajaxNewUser() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		String nome = request.getParameter("nome") ;
		String valore = request.getParameter("valore") ;
		RegExp regExp = new RegExp() ;
		JSONObject obj = new JSONObject() ;
		if (Pattern.matches(regExp.getItem(nome),valore)){
			obj.put("nome", nome) ;
			obj.put("valore", valore) ;
			
		}else{
			obj.put("nome", nome) ;
			valore="errore"+ nome;
			obj.put("valore", valore) ;
			
		}
		response.getWriter().write(obj.toJSONString()) ;
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response) ;
	}

}
Spero Che qualcuno possa aiutarmi!!!!

Vi ringrazio!!!