AJAX Call from JavaScript in Java

if(window.XMLHttpRequest)//non IE
{
    req = new XMLHttpRequest();
    try
    {
         req.open("GET",url,true);
         req.onreadystatechange=setInTextField;
    }
    catch(e)
    {
         alert("cannot connect to server");
    }
    req.send(null);
}
else if(window.ActiveXObject)//IE
{
    try
    {
         req=new ActiveXObject("Msxml2.XMLHTTP.3.0");
    }
    catch(e)
    {
         req=new ActiveXObject("Microsoft.XMLHTTP");
    }
    if(req)
    {
         req.open("GET",url,true);
         req.onreadystatechange=setInTextField;
         req.send(null);
    }
}