/**
* Executes a background task.
*
* <p>The task payload is either type Deferrable or Key; in the latter case, retrieve (then
* delete) the Deferrable instance from the datastore.
*/
@Override
public void doPost(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
try {
Object payload = deserialize(req);
if (payload instanceof Key) {
// get Deferrable from datastore
Blob taskBlob = (Blob) getDatastoreService().get((Key) payload).getProperty(TASK_PROPERTY);
deleteEntity((Key) payload);
if (taskBlob != null) {
payload = deserialize(taskBlob.getBytes());
}
}
if (payload instanceof Deferrable) {
((Deferrable) payload).doTask();
} else if (payload != null) {
log.severe("invalid payload type: " + payload.getClass().getName());
// don't retry task
}
} catch (EntityNotFoundException e) {
log.severe(e.toString()); // don't retry task
} catch (PermanentTaskFailure e) {
log.severe(e.toString()); // don't retry task
}
}
@Override
public void stateChanged(ChangeEvent e) {
Component selected = jtp.getSelectedComponent();
if (selected instanceof Deferrable) {
Deferrable deferrable = (Deferrable) selected;
if (!deferrable.isInitialized()) deferrable.initialize();
}
if (selected instanceof Controllable) {
JPanel controlPanel = ((Controllable) selected).getControlPanel();
if (controlPanel == null) clearSpecificTaskPane();
else
setSpecificTaskPane(
controlPanel,
jtp.getTitleAt(jtp.getSelectedIndex()),
jtp.getIconAt(jtp.getSelectedIndex()));
} else {
clearSpecificTaskPane();
}
}
