fileviewer.java

利用SWT作为开发用户界面

		createTreeDragSource(tree);
		createTreeDropTarget(tree);
	}

	/**
	 * Creates the Drag & Drop DragSource for items being dragged from the tree.
	 * 
	 * @return the DragSource for the tree
	 */
	private DragSource createTreeDragSource(final Tree tree){
		DragSource dragSource = new DragSource(tree, DND.DROP_MOVE | DND.DROP_COPY);
		dragSource.setTransfer(new Transfer[] { FileTransfer.getInstance() });
		dragSource.addDragListener(new DragSourceListener() {
			TreeItem[] dndSelection = null;
			String[] sourceNames = null;
			public void dragStart(DragSourceEvent event){
				dndSelection = tree.getSelection();
				sourceNames = null;
				event.doit = dndSelection.length > 0;
				isDragging = true;
				processedDropFiles = null;
			}
			public void dragFinished(DragSourceEvent event){
				dragSourceHandleDragFinished(event, sourceNames);
				dndSelection = null;
				sourceNames = null;
				isDragging = false;
				processedDropFiles = null;
				handleDeferredRefresh();
			}
			public void dragSetData(DragSourceEvent event){
				if (dndSelection == null || dndSelection.length == 0) return;
				if (! FileTransfer.getInstance().isSupportedType(event.dataType)) return;
				
				sourceNames  = new String[dndSelection.length];
				for (int i = 0; i < dndSelection.length; i++) {
					File file = (File) dndSelection[i].getData(TREEITEMDATA_FILE);
					sourceNames[i] = file.getAbsolutePath();
				}
				event.data = sourceNames;
			}
		});
		return dragSource;
	}

	/**
	 * Creates the Drag & Drop DropTarget for items being dropped onto the tree.
	 * 
	 * @return the DropTarget for the tree
	 */
	private DropTarget createTreeDropTarget(final Tree tree) {
		DropTarget dropTarget = new DropTarget(tree, DND.DROP_MOVE | DND.DROP_COPY);
		dropTarget.setTransfer(new Transfer[] { FileTransfer.getInstance() });
		dropTarget.addDropListener(new DropTargetAdapter() {
			public void dragEnter(DropTargetEvent event) {
				isDropping = true;
			}
			public void dragLeave(DropTargetEvent event) {
				isDropping = false;
				handleDeferredRefresh();
			}
			public void dragOver(DropTargetEvent event) {
				dropTargetValidate(event, getTargetFile(event));
				event.feedback |= DND.FEEDBACK_EXPAND | DND.FEEDBACK_SCROLL;
			}
			public void drop(DropTargetEvent event) {
				File targetFile = getTargetFile(event);
				if (dropTargetValidate(event, targetFile))
					dropTargetHandleDrop(event, targetFile);
			}
			private File getTargetFile(DropTargetEvent event) {
				// Determine the target File for the drop 
				TreeItem item = tree.getItem(tree.toControl(new Point(event.x, event.y)));
				File targetFile = null;
				if (item != null) {
					// We are over a particular item in the tree, use the item's file
					targetFile = (File) item.getData(TREEITEMDATA_FILE);
				}
				return targetFile;
			}
		});
		return dropTarget;	
	}

	/**
	 * Handles expand events on a tree item.
	 * 
	 * @param item the TreeItem to fill in
	 */
	private void treeExpandItem(TreeItem item) {
		shell.setCursor(iconCache.stockCursors[iconCache.cursorWait]);
		final Object stub = item.getData(TREEITEMDATA_STUB);
		if (stub == null) treeRefreshItem(item, true);
		shell.setCursor(iconCache.stockCursors[iconCache.cursorDefault]);
	}
	
	/**
	 * Traverse the entire tree and update only what has changed.
	 * 
	 * @param roots the root directory listing
	 */
	private void treeRefresh(File[] masterFiles) {
		TreeItem[] items = tree.getItems();
		int masterIndex = 0;
		int itemIndex = 0;
		for (int i = 0; i < items.length; ++i) {
			final TreeItem item = items[i];
			final File itemFile = (File) item.getData(TREEITEMDATA_FILE);
			if ((itemFile == null) || (masterIndex == masterFiles.length)) {
				// remove bad item or placeholder
				item.dispose();
				continue;
			}
			final File masterFile = masterFiles[masterIndex];
			int compare = compareFiles(masterFile, itemFile);
			if (compare == 0) {
				// same file, update it
				treeRefreshItem(item, false);
				++itemIndex;
				++masterIndex;
			} else if (compare < 0) {
				// should appear before file, insert it
				TreeItem newItem = new TreeItem(tree, SWT.NULL, itemIndex);
				treeInitVolume(newItem, masterFile);
				new TreeItem(newItem, SWT.NULL); // placeholder child item to get "expand" button
				++itemIndex;
				++masterIndex;
				--i;
			} else {
				// should appear after file, delete stale item
				item.dispose();
			}
		}
		for (;masterIndex < masterFiles.length; ++masterIndex) {
			final File masterFile = masterFiles[masterIndex];
			TreeItem newItem = new TreeItem(tree, SWT.NULL);
			treeInitVolume(newItem, masterFile);
			new TreeItem(newItem, SWT.NULL); // placeholder child item to get "expand" button
		}		
	}
	
	/**
	 * Traverse an item in the tree and update only what has changed.
	 * 
	 * @param dirItem the tree item of the directory
	 * @param forcePopulate true iff we should populate non-expanded items as well
	 */
	private void treeRefreshItem(TreeItem dirItem, boolean forcePopulate) {
		final File dir = (File) dirItem.getData(TREEITEMDATA_FILE);
		
		if (! forcePopulate && ! dirItem.getExpanded()) {
			// Refresh non-expanded item
			if (dirItem.getData(TREEITEMDATA_STUB) != null) {
				treeItemRemoveAll(dirItem);
				new TreeItem(dirItem, SWT.NULL); // placeholder child item to get "expand" button
				dirItem.setData(TREEITEMDATA_STUB, null);
			}
			return;
		}
		// Refresh expanded item
		dirItem.setData(TREEITEMDATA_STUB, this); // clear stub flag

		/* Get directory listing */
		File[] subFiles = (dir != null) ? FileViewer.getDirectoryList(dir) : null;
		if (subFiles == null || subFiles.length == 0) {
			/* Error or no contents */
			treeItemRemoveAll(dirItem);
			dirItem.setExpanded(false);
			return;
		}

		/* Refresh sub-items */
		TreeItem[] items = dirItem.getItems();
		final File[] masterFiles = subFiles;
		int masterIndex = 0;
		int itemIndex = 0;
		File masterFile = null;
		for (int i = 0; i < items.length; ++i) {
			while ((masterFile == null) && (masterIndex < masterFiles.length)) {
				masterFile = masterFiles[masterIndex++];
				if (! masterFile.isDirectory()) masterFile = null;
			}

			final TreeItem item = items[i];
			final File itemFile = (File) item.getData(TREEITEMDATA_FILE);
			if ((itemFile == null) || (masterFile == null)) {
				// remove bad item or placeholder
				item.dispose();
				continue;
			}
			int compare = compareFiles(masterFile, itemFile);
			if (compare == 0) {
				// same file, update it
				treeRefreshItem(item, false);
				masterFile = null;
				++itemIndex;
			} else if (compare < 0) {
				// should appear before file, insert it
				TreeItem newItem = new TreeItem(dirItem, SWT.NULL, itemIndex);
				treeInitFolder(newItem, masterFile);
				new TreeItem(newItem, SWT.NULL); // add a placeholder child item so we get the "expand" button
				masterFile = null;
				++itemIndex;
				--i;
			} else {
				// should appear after file, delete stale item
				item.dispose();
			}
		}
		while ((masterFile != null) || (masterIndex < masterFiles.length)) {
			if (masterFile != null) {
				TreeItem newItem = new TreeItem(dirItem, SWT.NULL);
				treeInitFolder(newItem, masterFile);
				new TreeItem(newItem, SWT.NULL); // add a placeholder child item so we get the "expand" button
				if (masterIndex == masterFiles.length) break;
			}
			masterFile = masterFiles[masterIndex++];
			if (! masterFile.isDirectory()) masterFile = null;
		}
	}

	/**
	 * Foreign method: removes all children of a TreeItem.
	 * @param treeItem the TreeItem
	 */
	private static void treeItemRemoveAll(TreeItem treeItem) {
		final TreeItem[] children = treeItem.getItems();
		for (int i = 0; i < children.length; ++i) {
			children[i].dispose();
		}
	}

	/**
	 * Initializes a folder item.
	 * 
	 * @param item the TreeItem to initialize
	 * @param folder the File associated with this TreeItem
	 */
	private void treeInitFolder(TreeItem item, File folder) {
		item.setText(folder.getName());
		item.setImage(iconCache.stockImages[iconCache.iconClosedFolder]);
		item.setData(TREEITEMDATA_FILE, folder);
		item.setData(TREEITEMDATA_IMAGEEXPANDED, iconCache.stockImages[iconCache.iconOpenFolder]);
		item.setData(TREEITEMDATA_IMAGECOLLAPSED, iconCache.stockImages[iconCache.iconClosedFolder]);
	}

	/**
	 * Initializes a volume item.
	 * 
	 * @param item the TreeItem to initialize
	 * @param volume the File associated with this TreeItem
	 */
	private void treeInitVolume(TreeItem item, File volume) {
		item.setText(volume.getPath());
		item.setImage(iconCache.stockImages[iconCache.iconClosedDrive]);
		item.setData(TREEITEMDATA_FILE, volume);
		item.setData(TREEITEMDATA_IMAGEEXPANDED, iconCache.stockImages[iconCache.iconOpenDrive]);
		item.setData(TREEITEMDATA_IMAGECOLLAPSED, iconCache.stockImages[iconCache.iconClosedDrive]);
	}

	/**
	 * Creates the file details table.
	 * 
	 * @param parent the parent control
	 */
	private void createTableView(Composite parent) {
		Composite composite = new Composite(parent, SWT.NONE);
		GridLayout gridLayout = new GridLayout();
		gridLayout.numColumns = 1;
		gridLayout.marginHeight = gridLayout.marginWidth = 2;
		gridLayout.horizontalSpacing = gridLayout.verticalSpacing = 0;
		composite.setLayout(gridLayout);
		tableContentsOfLabel = new Label(composite, SWT.BORDER);
		tableContentsOfLabel.setLayoutData(new GridData(GridData.FILL_HORIZONTAL | GridData.VERTICAL_ALIGN_FILL));

		table = new Table(composite, SWT.BORDER | SWT.V_SCROLL | SWT.H_SCROLL | SWT.MULTI | SWT.FULL_SELECTION);
		table.setLayoutData(new GridData(GridData.FILL_HORIZONTAL | GridData.FILL_VERTICAL));

		for (int i = 0; i < tableTitles.length; ++i) {
			TableColumn column = new TableColumn(table, SWT.NONE);
			column.setText(tableTitles[i]);
			column.setWidth(tableWidths[i]);
		}
		table.setHeaderVisible(true);
		table.addSelectionListener(new SelectionAdapter() {
			public void widgetSelected(SelectionEvent event) {
				notifySelectedFiles(getSelectedFiles());
			}
			public void widgetDefaultSelected(SelectionEvent event) {
				doDefaultFileAction(getSelectedFiles());
			}
			private File[] getSelectedFiles() {
				final TableItem[] items = table.getSelection();
				final File[] files = new File[items.length];
				
				for (int i = 0; i < items.length; ++i) {
					files[i] = (File) items[i].getData(TABLEITEMDATA_FILE);
				}
				return files;
			}
		});

		createTableDragSource(table);
		createTableDropTarget(table);
	}

	/**
	 * Creates the Drag & Drop DragSource for items being dragged from the table.
	 * 
	 * @return the DragSource for the table
	 */
	private DragSource createTableDragSource(final Table table) {
		DragSource dragSource = new DragSource(table, DND.DROP_MOVE | DND.DROP_COPY);
		dragSource.setTransfer(new Transfer[] { FileTransfer.getInstance() });
		dragSource.addDragListener(new DragSourceListener() {
			TableItem[] dndSelection = null;
			String[] sourceNames = null;
			public void dragStart(DragSourceEvent event){
				dndSelection = table.getSelection();
				sourceNames = null;
				event.doit = dndSelection.length > 0;
				isDragging = true;
			}
			public void dragFinished(DragSourceEvent event){
				dragSourceHandleDragFinished(event, sourceNames);
				dndSelection = null;
				sourceNames = null;
				isDragging = false;
				handleDeferredRefresh();
			}
			public void dragSetData(DragSourceEvent event){
				if (dndSelection == null || dndSelection.length == 0) return;
				if (! FileTransfer.getInstance().isSupportedType(event.dataType)) return;
				
				sourceNames  = new String[dndSelection.length];
				for (int i = 0; i < dndSelection.length; i++) {
					File file = (File) dndSelection[i].getData(TABLEITEMDATA_FILE);
					sourceNames[i] = file.getAbsolutePath();
				}
				event.data = sourceNames;
			}
		});
		return dragSource;
	}

	/**
	 * Creates the Drag & Drop DropTarget for items being dropped onto the table.
	 * 
	 * @return the DropTarget for the table
	 */
	private DropTarget createTableDropTarget(final Table table){
		DropTarget dropTarget = new DropTarget(table, DND.DROP_MOVE | DND.DROP_COPY);
		dropTarget.setTransfer(new Transfer[] { FileTransfer.getInstance() });
		dropTarget.addDropListener(new DropTargetAdapter() {
			public void dragEnter(DropTargetEvent event) {
				isDropping = true;
			}
			public void dragLeave(DropTargetEvent event) {
				isDropping = false;
				handleDeferredRefresh();
			}
			public void dragOver(DropTargetEvent event) {
				dropTargetValidate(event, getTargetFile(event));
				event.feedback |= DND.FEEDBACK_EXPAND | DND.FEEDBACK_SCROLL;
			}
			public void drop(DropTargetEvent event) {
				File targetFile = getTargetFile(event);
				if (dropTargetValidate(event, targetFile))
					dropTargetHandleDrop(event, targetFile);
			}
			private File getTargetFile(DropTargetEvent event) {
				// Determine the target File for the drop 
				TableItem item = table.getItem(table.toControl(new Point(event.x, event.y)));
				File targetFile = null;
				if (item == null) {
					// We are over an unoccupied area of the table.
					// If it is a COPY, we can use the table's root file.
					if (event.detail == DND.DROP_COPY) {
						targetFile = (File) table.getData(TABLEDATA_DIR);
					}
				} else {
					// We are over a particular item in the table, use the item's file
					targetFile = (File) item.getData(TABLEITEMDATA_FILE);
				}
				return targetFile;
			}
		});
		return dropTarget;
	}

	/**
	 * Notifies the application components that a new current directory has been selected
	 * 
	 * @param dir the directory that was selected, null is ignored
	 */
	void notifySelectedDirectory(File dir) {
		if (dir == null) return;
		if (currentDirectory != null && dir.equals(currentDirectory)) return;
		currentDirectory = dir;
		notifySelectedFiles(null);
		
		/* Shell:
		 * Sets the title to indicate the selected directory
		 */
		shell.setText(getResourceString("Title", new Object[] { currentDirectory.getPath() }));

		/* Table view:
		 * Displays the contents of the selected directory.
		 */
		workerUpdate(dir, false);

		/* Combo view:
		 * Sets the combo box to point to the selected directory.
		 */
		final File[] comboRoots = (File[]) combo.getData(COMBODATA_ROOTS);
		int comboEntry = -1;
		if (comboRoots != null) {		
			for (int i = 0; i < comboRoots.length; ++i) {
				if (dir.equals(comboRoots[i])) {
					comboEntry = i;
					break;
				}
			}
		}
		if (comboEntry == -1) combo.setText(dir.getPath());
		else combo.select(comboEntry);

		/* Tree view:
		 * If not already expanded, recursively expands the parents of the specified
		 * directory until it is visible.