Can't pass data using JsonpRequestBuilder

[Blake McBride]

Greetings,

I have a GWT app talking to a Java servlet just fine except I can't seem to pass data.  I've already spent a day on it.  Any help would be greatly appreciated.

I am using JsonpRequestBuilder and attempting to get around SOP.  Here is my server code:

public class GWTServlet extends HttpServlet {

protected void processRequest(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

String callback = request.getParameter("callback");

PrintWriter out = response.getWriter();

try {

out.print(callback + "([{\"Hello\": \"world\"}]);");

} finally {

out.close();

}

}....

Here is my GWT code:

public void onClick(ClickEvent event) {

JsonpRequestBuilder jsonprb= new JsonpRequestBuilder();

jsonprb.requestObject("http://localhost:8084/XXX/GWTServlet", 

new AsyncCallback() {

              @Override

              public void onFailure(Throwable caught) {

                  Window.alert("Failure getting JSONP directly from remote server");

              }

@Override

public void onSuccess(Object result) {

Window.alert("Got response");

JavaScriptObject res = (JavaScriptObject) result;

Window.alert(res.toSource());

}

          });

I get the "Got response" message.  I am also able to put break points on the frontend or backend and it gets to where I expect.  The problem is that I can't seem to get at the data send from the server.  I don't know what to do in onSuccess().

Of course, once I get this working I will have the same challenge going the other way.  Help is greatly appreciated.

Blake McBride

[Thomas Broyer]

Your server sends an array with a single item being an element with a "Hello" property, so your client code should use an AsyncCallback<JsArray<X>> where X is some JavaScriptObject subclass with a JSNI method getting the "Hello" property

class X extends JavaScriptObject {

    protected X() { /* required by JSO */ }

    public final native String getHello() /*-{ return this.Hello; }-*/;

}

...

jsonprb.requestObject(url, new AsyncCallback<JsArray<X>>() {

    @Override

    public void onSuccess(JsArray<X> result) {

       X firstX = result.get(0);

       Window.alert("Hello " + firstX.getHello());

    }

...

[Blake McBride]

Thanks.  That was a big help.  Ultimately, I am trying to pass XML.  The following worked for me:

Client:

public void onClick(ClickEvent event) {

JsonpRequestBuilder jsonprb= new JsonpRequestBuilder();

jsonprb.requestString("http://localhost:8084/Arahant/GWTServlet", 

new AsyncCallback<String>() {

                @Override

                public void onFailure(Throwable caught) {

                    Window.alert("Failure getting JSONP directly from remote server");

                }

@Override

public void onSuccess(String result) {

Window.alert("Got " + result);

}

            });

Server:

protected void processRequest(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

String callback = request.getParameter("callback");

PrintWriter out = response.getWriter();

try {

out.print(callback + "(\"Hello there\")");

} finally {

out.close();

}

}

I figure I'll stick XML in the string.

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