RCP 加载本地我的电脑树

package test.t1;
import org.eclipse.swt.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;

import java.io.*;
public class test {

	public static void main(String[] args) {
		final Display display = new Display ();
		final Shell shell = new Shell (display);
		shell.setText ("Lazy Tree");
		shell.setLayout (new FillLayout ());
		final Tree tree = new Tree (shell, SWT.BORDER| SWT.V_SCROLL | SWT.H_SCROLL);
		TreeItem r=new TreeItem(tree,0);
		r.setText("我的电脑");
		new TreeItem(r,0);
		File [] roots = File.listRoots ();
		for (int i=0; i<roots.length; i++) {
			TreeItem root = new TreeItem (r, 0);
			root.setText (roots [i].toString ());
			root.setData (roots [i]);
			new TreeItem (root, 0);
		}
		tree.addListener (SWT.Expand, new Listener () {
			@Override
			public void handleEvent (final Event event) {
				final TreeItem root = (TreeItem) event.item;
				TreeItem [] items = root.getItems ();
				for (int i= 0; i<items.length; i++) {
					if (items [i].getData () != null) return;
					items [i].dispose ();
				}
				File file = (File) root.getData ();
				File [] files = file.listFiles ();
				if (files == null) return;
				for (int i= 0; i<files.length; i++) {
					TreeItem item = new TreeItem (root, 0);
					item.setText (files [i].getName ());
					item.setData (files [i]);
					if (files [i].isDirectory()) {
						new TreeItem (item, 0);
					}
				}
			}
		});
		Point size = tree.computeSize (300, SWT.DEFAULT);
		int width = Math.max (300, size.x);
		int height = Math.max (300, size.y);
		shell.setSize (shell.computeSize (width, height));
		shell.open ();
		while (!shell.isDisposed ()) {
			if (!display.readAndDispatch ()) display.sleep ();
		}
		display.dispose ();
	}

}