Ajax i servleti - pocetak...

[ kooole @ 05.02.2008. 01:20 ] @

Danas sam prvi put pokusao da uradim nesto sa Ajaxom i odmah zapelo. Pratio sam tutorial sa sun-ovog sajta, molio bih vas da pogledate gde gresim.
Evo JSP strane:

Code:

<%@page contentType="text/html; charset=UTF-8" %>
<html>

<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title> Web mail </title>
<script type="text/javascript" >

    function getXmlRequest()
    {
        var xmlHttp;
        try
          {
              // Firefox, Opera 8.0+, Safari
              xmlHttp=new XMLHttpRequest();
          }
        catch (e)
          {
              // Internet Explorer
              try
            {
                xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
            }
              catch (e)
            {
                try
                  {
                      xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
                  }
                catch (e)
                  {
                      alert("Your browser does not support AJAX!");
                      return null;
                  }
            }
          }

        return xmlHttp;
    }


    function setMessage(message) {
        var mdiv = document.getElementById("userIdMessage");
           mdiv.innerHTML = "<div style=\"color:red\">Message: "+message+"</ div>";
        }

    function saberi()
    {
        var req;
        req = getXmlRequest();

        if (req!=null)
        {
            var idField = document.getElementById("userid");
               var url = "/WebProjectTest/sabServlet?sab1=20&sab2=11";
               req.open("GET", url, true);
               req.onreadystatechange = function()
            {
                if (req.readyState == 4) {
                        alert("Response (responseText) : " + req.getResponseText);
                        alert("Response (getElementByTagName) " + req.responseXML.getElementsByTagName("message")[0]);
                         var message = req.responseXML.getElementsByTagName("message")[0];
                         setMessage(message.childNodes[0].nodeValue);
                       }
            };
           req.send(null);
        }
    }

</script>

</head>
<body>
    <h1> TEST  </h1>
      <form action="/WebProjectTest/startServlet" method="post">

        <table border="0">
            <tr>
                  <td>Rezultat</td>
                  <td> <div id="userIdMessage"></div></td>
              <tr>
            <tr>
                  <td><input type="Button" onclick="saberi();"></td>
              <tr>
        </table>
      </form>
</body>

</html>

A evo i Servlet-a, odnosno njegove doGet metode:

Code:

    protected void doGet(HttpServletRequest req, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        super.doGet(req, response);

         String sab1 = req.getParameter("sab1");
         String sab2 = req.getParameter("sab2");

         System.out.println("Sab 1 i 2 su: " + sab1 + sab2);

         response.setContentType("text/xml");
         response.setHeader("Cache-Control", "no-cache");
         response.getWriter().write("<message>"+ sab1 + sab2 +"</message>");

    }

Ne obracajte mnogo paznju na logiku jer ovo je glupost koja samo treba da proradi i nista vise. Zabetonirao sam dva parametra u samom kodu, i sve sto zelim je da pri kliku na dugme server spoji ta dva parametra u jedan string i prikaze na klijentskoj strani taj string. Problem nastaje u funkciji req.onreadystatechange = function()... prvi alert mi prikazuje "undefined", a drugi "null"... kao da nista nije primljeno sa servera???