Question

I am using XMLHttpRequest to create a simple form submitand get session variable from the servlet. But nothing seems to work. Can somebody point out where am I going wrong?

Here is the Form

<form method="post" target="_self" action="/temp/Welcome.html">
    <table>
        <tr>
            <td>Email</td>
            <td><input type="text" id="email" name="email" value="[e-mail]"></td>
        </tr>
        <tr>
            <td>Project ID</td>
            <td><input type="text" id="projectid" name="projectid" value="1111"></td>
        </tr>
        <tr>
            <td colspan="2" align="right"><input type="button" id="submitbutton" value="Submit" onclick="submitLogin()"></td>
        </tr>
    </table>
</form>

here is the submitLogin function

function submitLogin()
{
 var url_action="/temp/Login";
 var client; 
 var dataString;
 if (client.XMLHttpRequest){ // IE7+, Firefox, Chrome, Opera, Safari
     client=new XMLHttpRequest();
 } else {                    // IE6, IE5
     client=new ActiveXObject("Microsoft.XMLHTTP");
 }

 client.onreadystatechange=function(){
     alert(client.responseText);
     if(client.readyState==4&&client.status==200)
     {
         alert(client.responseText);
     }
     else
         alert("Error: return status code "+client.status+" "+client.statusText);
 };
 dataString="email="+document.getElementById("email").value;
 client.open("POST",url_action,true);
 client.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

 client.send(dataString);
}

and my post method in Login.java servlet

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    PrintWriter out = response.getWriter();
    response.setContentType("text/plain");

    paramMap=request.getParameterMap();
    if (paramMap == null)
        throw new ServletException(
          "getParameterMap returned null in: " + getClass().getName());

    iterator=paramMap.entrySet().iterator();
    //System.out.println(paramMap.size());
    String str="";

    while(iterator.hasNext())
    {
        Map.Entry me=(Map.Entry)iterator.next();
        String[] arr=(String[])me.getValue();
        emailId=arr[0];
        //System.out.println(me.getKey()+" > "+emailId);

    }
    rand=new Random();
    randomInt=rand.nextInt(1000000);
    emailId=randomInt+emailId;
    System.out.println(emailId);
    out.println(emailId);

    /*creates a new session if a session does not exist already*/
    session=request.getSession();
    session.setAttribute("uid", emailId);

    out.close();
}

None of the alerts and the System.out seems to show any response. please guide me. Thanks

Note: in IE 8 it shows xmlhttprequest is null or not an object, login.js at Line no: 9

Answer 1

Looks like you have a simple typo in your Java Script

var client; 

if (client.XMLHttpRequest){
    client=new XMLHttpRequest();
} else {
    client=new ActiveXObject("Microsoft.XMLHTTP");
}

You are declaring some variable called client and asking it for it’s XMLHttpRequest member. You probably meant to use window.XMLHttpRequest.