将图片上传到Blob存储

Question

i have uploaded an image to blob-store by applying the example here

https://developers.google.com/appengine/docs/java/blobstore/

and it worked just fine.. but when i removed the (index.jsp) file and used a formPanel and (com.google.gwt.user.client.ui.FileUpload) to upload my file it appeared on the datastore Viewer but couldn't see it on screen.help??

another issue that if i want to view the uploaded image on another view of my project, how can i handle that.. I'm very new to web-application field and need alittle explanation please.. thanks .

Answer 1

The FormPanel use an hidden iframe for send form request.

You can use a NamedFrame :

String actionUrl = getActionURLFromServer();
NamedFrame frame = new NamedFrame("iframe");
frame.setSize("400px","600px");
final FormPanel form = new FormPanel(frame);
form.setEncoding(FormPanel.ENCODING_MULTIPART);
form.setMethod(FormPanel.METHOD_POST);
form.setAction(actionUrl);
FileUpload upload = new FileUpload();
upload.setName("myFile");
upload.addChangeHandler(new ChangeHandler() {
  void onChange(ChangeEvent event) {
    form.submit();
  }
});
form.setWidget(upload);
RootPanel.get().add(form);
RootPanel.get().add(frame);