gwt file upload code - gwt

Question

I want to upload file in my application and want to set path where the files should be saved after uploading in my local system.I am using the following code but on the submit button getting no response while clicking.Please tell me the code which works fine for the file upload in gwt.
[code]
public class FormPanelExample implements EntryPoint {
public void onModuleLoad() {
// Create a FormPanel and point it at a service.
final FormPanel form = new FormPanel();
form.setAction("/myFormHandler");
// Because we're going to add a FileUpload widget, we'll need to set the
// form to use the POST method, and multipart MIME encoding.
form.setEncoding(FormPanel.ENCODING_MULTIPART);
form.setMethod(FormPanel.METHOD_POST);
// Create a panel to hold all of the form widgets.
VerticalPanel panel = new VerticalPanel();
form.setWidget(panel);
// Create a TextBox, giving it a name so that it will be submitted.
final TextBox tb = new TextBox();
tb.setName("textBoxFormElement");
panel.add(tb);
// Create a ListBox, giving it a name and some values to be associated with
// its options.
ListBox lb = new ListBox();
lb.setName("listBoxFormElement");
lb.addItem("foo", "fooValue");
lb.addItem("bar", "barValue");
lb.addItem("baz", "bazValue");
panel.add(lb);
// Create a FileUpload widget.
FileUpload upload = new FileUpload();
upload.setName("uploadFormElement");
panel.add(upload);
// Add a 'submit' button.
panel.add(new Button("Submit", new ClickListener() {
public void onClick(Widget sender) {
form.submit();
}
}));
// Add an event handler to the form.
form.addFormHandler(new FormHandler() {
public void onSubmit(FormSubmitEvent event) {
// This event is fired just before the form is submitted. We can take
// this opportunity to perform validation.
if (tb.getText().length() == 0) {
Window.alert("The text box must not be empty");
event.setCancelled(true);
}
}
public void onSubmitComplete(FormSubmitCompleteEvent event) {
// When the form submission is successfully completed, this event is
// fired. Assuming the service returned a response of type text/html,
// we can get the result text here (see the FormPanel documentation for
// further explanation).
Window.alert(event.getResults());
}
});
RootPanel.get().add(form);
}
}
Thanks
Amandeep

Answer 1

Now, I remember.. There's a bug in the FormPanel code that causes form.submit() not to work, when the type of the form is changed from the default (don't know if it's fixed yet in any release of GWT). If you create a "native" submit button like this:
HTML nativeSubmitButton new HTML("<input class='gwt-Button' type='submit' value='" + buttonText + "' />")
It will submit the form.
The disadvantage is that you cannot use any Button methods on this object, since it's a simple HTML wrapper. So disabling the button on submit (to avoid accidental double submit, and to give feedback that the form is actually submitting) won't work .
I've created a utility class for this purpose myself called DisableableSubmitButton that is essentially a FlowPanel with one HTML button like the above, and one gwt Button that is disabled, and some logic to toggle each of them visible. Since it cannot modify the actual enabled status of the HTML button all submit handlers must ask this class if it's "enabled" or not and cancel the event if it is. If you're interested in this implementation, i could share it with you (I don't want to flood stackoverflow with code unless you are interested).