Listing 2. Source Code for the JSONRequest Class

package com.kereki.client;
public class JSONRequest {
    public static void get(String url,
                           JSONRequestHandler handler) {
        String callbackName = "JSONCallback"+handler.hashCode();
        get(url+callbackName, callbackName, handler);
    }

    public static void get(String url, String callbackName,
                           JSONRequestHandler handler) {
        createCallbackFunction(handler, callbackName);
        addScript(url);
    }

    public static native void addScript(String url) /*-{
        var scr = document.createElement("script");
        scr.setAttribute("language", "JavaScript");
        scr.setAttribute("src", url);
        document.getElementsByTagName("body")[0].appendChild(scr);
    }-*/;

    private native static void createCallbackFunction(
                                   JSONRequestHandler obj,
                                   String callbackName) /*-{
        tmpcallback = function(j) {
            obj.@com.kereki.client.JSONRequestHandler::
                onRequestComplete(
                    Lcom/google/gwt/core/client/JavaScriptObject;)(j);
        };
        eval( "window." + callbackName + "=tmpcallback" );
    }-*/;
}