GXT Paging Grid With Remote Search

I'm using paging grid in GXT to view a list.
The basic is shown below:

ScriptTagProxy<PagingLoadResult<ModelData>> proxy = new ScriptTagProxy<PagingLoadResult<ModelData>>(url);
JsonPagingLoadResultReader<PagingLoadResult<ModelData>> reader = new JsonPagingLoadResultReader<PagingLoadResult<ModelData>>(type);
final PagingLoader<PagingLoadResult<ModelData>> loader = new BasePagingLoader<PagingLoadResult<ModelData>>(proxy, reader);
loader.setRemoteSort(true);
final ListStore<ModelData> mystore = new ListStore<ModelData>(loader);
return mystore;

But I want to use the same paging component for remote search. Finally I came out with this solution.

private void searchStaff() {
 String url = "index.php?option=com_model&model={0}&action=getStaffList";
 PagingLoadConfig config = new BasePagingLoadConfig();
 config.setOffset(0);
 config.setLimit(50);

 BasePagingLoader loader = ((BasePagingLoader) store.getLoader());
 ScriptTagProxy proxy = (ScriptTagProxy) loader.getProxy();
 if (keyword.getValue() == null || keyword.getValue().equals("")) {
 } else {
     url += "&keyword=" + keyword.getValue().toString();
 }
 url = url.replace("{0}", "Staff");
 url = DataUtils.formatURL(url);
 url = url.replaceAll("kpiwebgwt", "kpiweb");
 proxy.setUrl(url);
 store.getLoader().load(config);
}