import org.eclipse.ui.actions.CloseResourceAction; //导入依赖的package包/类
/**
 * Creates a new <code>ProjectActionGroup</code>. The group requires
 * that the selection provided by the given selection provider is of type
 * {@link IStructuredSelection}.
 *
 * @param site the site that will own the action group.
 * @param selectionProvider the selection provider used instead of the
 *  page selection provider.
 *
 * @since 3.4
 */
public ProjectActionGroup(IWorkbenchSite site, ISelectionProvider selectionProvider) {
	fSelectionProvider= selectionProvider;
	ISelection selection= selectionProvider.getSelection();

	fCloseAction= new CloseResourceAction(site);
	fCloseAction.setActionDefinitionId(IWorkbenchCommandConstants.PROJECT_CLOSE_PROJECT);

	fCloseUnrelatedAction= new CloseUnrelatedProjectsAction(site);
	fCloseUnrelatedAction.setActionDefinitionId(IWorkbenchCommandConstants.PROJECT_CLOSE_UNRELATED_PROJECTS);

	fOpenAction= new OpenProjectAction(site);
	fOpenAction.setActionDefinitionId(IWorkbenchCommandConstants.PROJECT_OPEN_PROJECT);
	if (selection instanceof IStructuredSelection) {
		IStructuredSelection s= (IStructuredSelection)selection;
		fOpenAction.selectionChanged(s);
		fCloseAction.selectionChanged(s);
		fCloseUnrelatedAction.selectionChanged(s);
	}

	fSelectionChangedListener= new ISelectionChangedListener() {
		public void selectionChanged(SelectionChangedEvent event) {
			ISelection s= event.getSelection();
			if (s instanceof IStructuredSelection) {
				performSelectionChanged((IStructuredSelection) s);
			}
		}
	};
	selectionProvider.addSelectionChangedListener(fSelectionChangedListener);

	IWorkspace workspace= ResourcesPlugin.getWorkspace();
	workspace.addResourceChangeListener(fOpenAction);
	workspace.addResourceChangeListener(fCloseAction);
	workspace.addResourceChangeListener(fCloseUnrelatedAction);
}