How to pass parameters to controller using ajax and javascript? -

i trying delete item shopping cart using ajax javascript, have trouble passing parameters controller. parameters null in controller.

my javascript code shows below:

function removerow(itemid, rowid){         if (xmlhttp == null)         {             alert("your browser not support ajax!");             return;         }         var query = "action=remove&item=" + itemid;          /* alert(query); */         xmlhttp.onreadystatechange = function statechanged()         {             if (xmlhttp.readystate == 4)             {                 var row = document.getelementbyid(rowid);                 row.parentnode.removechild(row);             }         };         xmlhttp.open("get", "addto.htm", true);         xmlhttp.setrequestheader("content-type", "application/x-www-form-urlencoded");         xmlhttp.send(query);         return false;          /* var row = document.getelementbyid(rowid);         row.parentnode.removechild(row); */ 

}

my controller code shows below:

@controller  @requestmapping("/addto.htm") public class addtocontroller{     @requestmapping(method=requestmethod.get)     protected modelandview handlerequestinternal(httpservletrequest request, httpservletresponse response) throws exception {         httpsession session = request.getsession();         string action = request.getparameter("action");         system.out.println(action);         modelandview mv = new modelandview();         arraylist<item> cart;         if(action.equals("remove")){             system.out.println("cart size is" + cart.size());             long itemid = long.parselong(request.getparameter("item"));             itemdao itemdao= new itemdao();             item item = itemdao.get(itemid);             cart.remove(item);             system.out.println(cart.size());         }         return mv;     } } 

the action , item null in controller.

can problem?

you're sending request, add parameters query after url:

xmlhttp.open("get", "addto.htm?" + query, true); 

and pass in null (rather query string) when calling .send method:

xmlhttp.send(null); 

also, "application/x-www-form-urlencoded" header used when you're sending serialised parameters using post, remove xmlhttp.setrequestheader line.

more info: https://developer.mozilla.org/en-us/docs/ajax/getting_started