I think what you are missing is the function name in your output from
the servlet. From what I see, you just return:
[{color: \"red\",value: \"#f00\"}]
when I would expect a response something like:
mycallback([{color: \"red\",value: \"#f00\"}])
where the "mycallback" is the name of the function you add to the DOM
which calls your handleJSONResponse method - without returning a
function from your servlet, I'm not sure how your handle method is
being called.
Also, are you defining your callback code to pick up the parameter,
e.g.
public native static void setup(YourHandlerClass h, String callback) /
*-{
window[callback] = function(someData) {
[EMAIL PROTECTED]::handleJSONResponse(Lcom/
google/gwt/core/client/JavaScriptObject;)(someData);
}
}-*/;
without the (Lcom/google/gwt/core/client/JavaScriptObject;)(someData)
part it won't pick up the returned data
//Adam
On 7 Okt, 10:14, eggsy84 <[EMAIL PROTECTED]> wrote:
> Hi Adam,
>
> Thank you for the reply it definately helps! when you say it needs to
> be well-formed javascript I have implemented a method that performs
> the following:
>
> /* (non-Javadoc)
> * @see
> javax.servlet.http.HttpServlet#doPost(javax.servlet.http.HttpServletRequest,
> javax.servlet.http.HttpServletResponse)
> */
> @Override
> protected void doPost(HttpServletRequest req, HttpServletResponse
> resp) throws ServletException, IOException
> {
> String output ="[{color: \"red\",value: \"#f00\"}]";
> resp.setContentType("text/javascript");
> resp.addHeader("Pragma", "no-cache");
> resp.setStatus(200);
> PrintWriter out = resp.getWriter();
> out.println(output);
>
> }
>
> Would that be sufficient? Well I ask the question but I assume not as
> with my implementation I successfully go back to my client handle
> method now but the JavascriptObject passed in is always null.
>
> My client side handle method is very basic as a test (shown below) and
> I can confirm that when the claa is complete is definately hits this
> method so the glue between is wrong somehow?
>
> public void handleJsonResponse(JavaScriptObject jso)
> {
> if (jso == null)
> {
> Window.alert("Unable to parse JSON");
> return;
> }
> else
> {
> Window.alert("Well done Woohoo!!");
> }
>
> }
>
> eggsy
>
> On Oct 6, 9:28 pm, Adam T <[EMAIL PROTECTED]> wrote:
>
> > Eggsy,
>
> > To get it to work you need to get the plumbing right, and it's not
> > quite the same way as calling from code - btw, the example on that
> > page is aimed at client side not server side. The server is any
> > language you want as long as it returns a well-formed JavaScript
> > segment of the form:
>
> > mycallback({....some json content....})
>
> > So your servlet would work as long as it returns something like the
> > above.
>
> > In this approach you don't call the servlet in the normal way from the
> > program code, rather it gets called as a consequence of adding a
> > <script> tag to the DOM - this is what the addScript() method in the
> > example code does. Once the script is added to the DOM the browser
> > accesses the defined url of your service and expects a response. As
> > the response is a JavaScript function, it will get evaluated in the
> > browser.
>
> > If you also define a function in the DOM with the same name you expect
> > back in the server response, e.g. mycallback, and that function calls
> > the GWT handle() function then the loop is closed. The example code
> > adds such a function using the setUp() method.
>
> > The example code reserves a new function name for each "call" made to
> > the server, adds that new function to the DOM and then the <script>
> > tag.
>
> > Where things usually go wrong are if the server returns a function
> > name not set up, or the response is not a valid javascript expression.
>
> > Hope that helps in some small way!
>
> > //Adam
>
> > this then gets evaluated in the browser
>
> > On 6 Okt, 17:02, eggsy84 <[EMAIL PROTECTED]> wrote:
>
> > > Hi all,
>
> > > Taking the informative article by Dan Morrill at GWT
>
> > > Link:http://code.google.com/support/bin/answer.py?answer=65632&topic=11368
>
> > > It explains how to code for Server side mashups so that you can
> > > perform cross site JSONP calls.
>
> > > In the article he uses the handle method (Shown below) to handle the
> > > return from the server side:
>
> > > public void handle(JavaScriptObject jso) {
> > > JSONObject json = new JSONObject(jso);
> > > JSONArray ary =
> > > json.get("feed").isObject().get("entry").isArray();
> > > for (int i = 0; i < ary.size(); ++i) {
> > > RootPanel.get().add(new
> > > Label(ary.get(i).isObject().get("title").isObject().get("$t").toString()));
> > > }
> > > }
>
> > > I have tried writing my own basic Java Servlet GET/POST we all know
> > > the score and I can successfully call into my servlet but I never get
> > > back to my client side, in this case after the servlet has done its
> > > stuff, I never go back to the handle method to perform some whizz bang
> > > GWT stuff - is there something specific you are required to do on the
> > > server side? Such as extends RemoteServiceServlet as you would do in a
> > > normal GWT AsyncCallback call? Anyone got any ideas?
>
> > > Thanks all
>
> > > eggsy
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