JDT:Choose Source Container Dialog(选择src目录的功能)

源码位于org.eclipse.jdt.ui.wizards.NewContainerWizardPage类中，注意一下ElementTreeSelectionDialog对话框的使用。

// ------------- choose source container dialog
	/**
	 * Opens a selection dialog that allows to select a source container.
	 *
	 * @return returns the selected package fragment root  or null if the dialog has been canceled.
	 * The caller typically sets the result to the container input field.
	 * 

	 * Clients can override this method if they want to offer a different dialog.
	 * 
	 *
	 * @since 3.2
	 */
	protected IPackageFragmentRoot chooseContainer() {
		IJavaElement initElement= getPackageFragmentRoot();
		Class[] acceptedClasses= new Class[] { IPackageFragmentRoot.class, IJavaProject.class };
		TypedElementSelectionValidator validator= new TypedElementSelectionValidator(acceptedClasses, false) {
			public boolean isSelectedValid(Object element) {
				try {
					if (element instanceof IJavaProject) {
						IJavaProject jproject= (IJavaProject)element;
						IPath path= jproject.getProject().getFullPath();
						return (jproject.findPackageFragmentRoot(path) != null);
					} else if (element instanceof IPackageFragmentRoot) {
						return (((IPackageFragmentRoot)element).getKind() == IPackageFragmentRoot.K_SOURCE);
					}
					return true;
				} catch (JavaModelException e) {
					JavaPlugin.log(e.getStatus()); // just log, no UI in validation
				}
				return false;
			}
		};

		acceptedClasses= new Class[] { IJavaModel.class, IPackageFragmentRoot.class, IJavaProject.class };
		ViewerFilter filter= new TypedViewerFilter(acceptedClasses) {
			public boolean select(Viewer viewer, Object parent, Object element) {
				if (element instanceof IPackageFragmentRoot) {
					try {
						return (((IPackageFragmentRoot)element).getKind() == IPackageFragmentRoot.K_SOURCE);
					} catch (JavaModelException e) {
						JavaPlugin.log(e.getStatus()); // just log, no UI in validation
						return false;
					}
				}
				return super.select(viewer, parent, element);
			}
		};

		StandardJavaElementContentProvider provider= new StandardJavaElementContentProvider();
		ILabelProvider labelProvider= new JavaElementLabelProvider(JavaElementLabelProvider.SHOW_DEFAULT);
		ElementTreeSelectionDialog dialog= new ElementTreeSelectionDialog(getShell(), labelProvider, provider);
		dialog.setValidator(validator);
		dialog.setComparator(new JavaElementComparator());
		dialog.setTitle(NewWizardMessages.NewContainerWizardPage_ChooseSourceContainerDialog_title);
		dialog.setMessage(NewWizardMessages.NewContainerWizardPage_ChooseSourceContainerDialog_description);
		dialog.addFilter(filter);
		dialog.setInput(JavaCore.create(fWorkspaceRoot));
		dialog.setInitialSelection(initElement);
		dialog.setHelpAvailable(false);

		if (dialog.open() == Window.OK) {
			Object element= dialog.getFirstResult();
			if (element instanceof IJavaProject) {
				IJavaProject jproject= (IJavaProject)element;
				return jproject.getPackageFragmentRoot(jproject.getProject());
			} else if (element instanceof IPackageFragmentRoot) {
				return (IPackageFragmentRoot)element;
			}
			return null;
		}
		return null;
	}

说明：
IPackageFragmentRoot接口表示一组包段，并将各段映射至底层资源，它可以是文件夹、JAR或ZIP文件。此处是返回源码包，判断如下：
(((IPackageFragmentRoot)element).getKind() == IPackageFragmentRoot.K_SOURCE