java swing的拖放例子

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我从java.sun.com和javaworld.com上的例子改过来的一棵文件系统树,支持拖放,CTRL+V复制文件

import java.awt.AlphaComposite;
import java.awt.Component;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Toolkit;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.StringSelection;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DragGestureEvent;
import java.awt.dnd.DragGestureListener;
import java.awt.dnd.DragSource;
import java.awt.dnd.DragSourceDragEvent;
import java.awt.dnd.DragSourceDropEvent;
import java.awt.dnd.DragSourceEvent;
import java.awt.dnd.DragSourceListener;
import java.awt.dnd.DropTarget;
import java.awt.dnd.DropTargetDragEvent;
import java.awt.dnd.DropTargetDropEvent;
import java.awt.dnd.DropTargetEvent;
import java.awt.dnd.DropTargetListener;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.geom.AffineTransform;
import java.awt.geom.Rectangle2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;

import javax.swing.Icon;
import javax.swing.JLabel;
import javax.swing.JTree;
import javax.swing.Timer;
import javax.swing.event.TreeExpansionEvent;
import javax.swing.event.TreeExpansionListener;
import javax.swing.filechooser.FileSystemView;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreePath;

class DragTree extends JTree implements DragGestureListener,
        DragSourceListener, DropTargetListener {
    BufferedImage ghostImage;

    private Rectangle2D ghostRect = new Rectangle2D.Float();

    private Point ptOffset = new Point();

    private Point lastPoint = new Point();

    private TreePath lastPath;

    private Timer hoverTimer;

    FileNode sourceNode;

    public DragTree() {
        DragSource dragSource = DragSource.getDefaultDragSource();

        dragSource.createDefaultDragGestureRecognizer(this, // component where
                // drag originates
                DnDConstants.ACTION_COPY_OR_MOVE, // actions
                this); // drag gesture recognizer
        setModel(createTreeModel());

        addTreeExpansionListener(new TreeExpansionListener() {
            public void treeCollapsed(TreeExpansionEvent e) {
            }

            public void treeExpanded(TreeExpansionEvent e) {
                TreePath path = e.getPath();

                if (path != null) {
                    FileNode node = (FileNode) path.getLastPathComponent();

                    if (!node.isExplored()) {
                        DefaultTreeModel model = (DefaultTreeModel) getModel();
                        node.explore();
                        model.nodeStructureChanged(node);
                    }
                }
            }
        });
        this.setCellRenderer(new DefaultTreeCellRenderer() {

            public Component getTreeCellRendererComponent(JTree tree,
                    Object value, boolean selected, boolean expanded,
                    boolean leaf, int row, boolean hasFocus) {
                TreePath tp = tree.getPathForRow(row);
                if (tp != null) {
                    FileNode node = (FileNode) tp.getLastPathComponent();
                    File f = node.getFile();
                    try {
                        Icon icon = FileSystemView.getFileSystemView()
                                .getSystemIcon(f);
                        this.setIcon(icon);
                        this.setLeafIcon(icon);
                        this.setOpenIcon(icon);
                        this.setClosedIcon(icon);
                        this.setDisabledIcon(icon);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                return super.getTreeCellRendererComponent(tree, value,
                        selected, expanded, leaf, row, hasFocus);
            }

        });

        super.setScrollsOnExpand(true);
        new DropTarget(this, DnDConstants.ACTION_COPY_OR_MOVE, this);

        //      Set up a hover timer, so that a node will be automatically expanded
        // or collapsed
        // if the user lingers on it for more than a short time
        hoverTimer = new Timer(1000, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (lastPath == null) {
                    return;
                }
                if (getRowForPath(lastPath) == 0)
                    return; // Do nothing if we are hovering over the root node
                if (isExpanded(lastPath))
                    collapsePath(lastPath);
                else
                    expandPath(lastPath);
            }
        });
        hoverTimer.setRepeats(false); // Set timer to one-shot mode

        this.addKeyListener(new KeyAdapter() {

            public void keyPressed(KeyEvent e) {
                int code = e.getKeyCode();
                int modifiers = e.getModifiers();
                if (code == 'v' || code == 'V') {
                    System.out.println("find v");
                    System.out.println("modifiers:" + modifiers + "\t"
                            + ((modifiers & KeyEvent.CTRL_MASK) != 0));
                }

                if ((modifiers & KeyEvent.CTRL_MASK) != 0
                        && (code == 'v' || code == 'V')) {
                    Transferable tr = Toolkit.getDefaultToolkit()
                            .getSystemClipboard().getContents(null);

                    TreePath path = getSelectionPath();
                    if (path == null) {
                        return;
                    }
                    FileNode node = (FileNode) path.getLastPathComponent();
                    if (node.isDirectory()) {
                        System.out.println("file cp");
                        try {
                            List list = (List) (tr
                                    .getTransferData(DataFlavor.javaFileListFlavor));
                            Iterator iterator = list.iterator();
                            File parent = node.getFile();
                            while (iterator.hasNext()) {
                                File f = (File) iterator.next();
                                cp(f, new File(parent, f.getName()));
                            }
                            node.reexplore();
                        } catch (Exception ioe) {
                            ioe.printStackTrace();
                        }
                        updateUI();
                    }
                }
            }

        });
    }

    public void dragGestureRecognized(DragGestureEvent e) {
        // drag anything ...

        TreePath path = getLeadSelectionPath();
        if (path == null)
            return;
        FileNode node = (FileNode) path.getLastPathComponent();
        sourceNode = node;
        //      Work out the offset of the drag point from the TreePath bounding
        // rectangle origin
        Rectangle raPath = getPathBounds(path);
        Point ptDragOrigin = e.getDragOrigin();
        ptOffset.setLocation(ptDragOrigin.x - raPath.x, ptDragOrigin.y
                - raPath.y);
        //      Get the cell renderer (which is a JLabel) for the path being dragged
        int row = this.getRowForLocation(ptDragOrigin.x, ptDragOrigin.y);
        JLabel lbl = (JLabel) getCellRenderer().getTreeCellRendererComponent(
                this, // tree
                path.getLastPathComponent(), // value
                false, // isSelected (dont want a colored background)
                isExpanded(path), // isExpanded
                getModel().isLeaf(path.getLastPathComponent()), // isLeaf
                row, // row (not important for rendering)
                false // hasFocus (dont want a focus rectangle)
                );
        lbl.setSize((int) raPath.getWidth(), (int) raPath.getHeight()); // <--
        // The
        // layout
        // manager
        // would
        // normally
        // do
        // this

        // Get a buffered image of the selection for dragging a ghost image
        this.ghostImage = new BufferedImage((int) raPath.getWidth(),
                (int) raPath.getHeight(), BufferedImage.TYPE_INT_ARGB_PRE);
        Graphics2D g2 = ghostImage.createGraphics();

        // Ask the cell renderer to paint itself into the BufferedImage
        g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC, 0.5f));
        // Make the image ghostlike
        lbl.paint(g2);

        g2.dispose();
        //this.getGraphics().drawImage(ghostImage, e.getDragOrigin().x,
        //        e.getDragOrigin().y, this);

        e.startDrag(null, // cursor
                ghostImage, new Point(5, 5),
                new StringSelection(getFilename()), // transferable
                this); // drag source listener
    }

    public void dragDropEnd(DragSourceDropEvent e) {
        ghostImage = null;
        sourceNode = null;
    }

    public void dragEnter(DragSourceDragEvent e) {
    }

    public void dragExit(DragSourceEvent e) {
        if (!DragSource.isDragImageSupported()) {
            repaint(ghostRect.getBounds());
        }
    }

    public void dragOver(DragSourceDragEvent e) {

    }

    public void dropActionChanged(DragSourceDragEvent e) {
    }

    public String getFilename() {
        TreePath path = getLeadSelectionPath();
        FileNode node = (FileNode) path.getLastPathComponent();
        return ((File) node.getUserObject()).getAbsolutePath();
    }

    private DefaultTreeModel createTreeModel() {
        File root = FileSystemView.getFileSystemView().getRoots()[0];
        FileNode rootNode = new FileNode(root);

        rootNode.explore();
        return new DefaultTreeModel(rootNode);
    }

    public void dragEnter(DropTargetDragEvent dtde) {

    }

    public void dragOver(DropTargetDragEvent dtde) {

        Point pt = dtde.getLocation();
        if (pt.equals(lastPoint)) {
            return;
        }
        if (ghostImage != null) {
            Graphics2D g2 = (Graphics2D) getGraphics();
            // If a drag image is not supported by the platform, then draw my
            // own drag image
            if (!DragSource.isDragImageSupported()) {
                paintImmediately(ghostRect.getBounds()); // Rub out the last
                // ghost image and cue
                // line
                // And remember where we are about to draw the new ghost image
                ghostRect.setRect(pt.x - ptOffset.x, pt.y - ptOffset.y,
                        ghostImage.getWidth(), ghostImage.getHeight());
                g2.drawImage((ghostImage), AffineTransform
                        .getTranslateInstance(ghostRect.getX(), ghostRect
                                .getY()), null);
            }
        }
        TreePath path = getClosestPathForLocation(pt.x, pt.y);
        if (!(path == lastPath)) {
            lastPath = path;
            hoverTimer.restart();
        }
    }

    public void dropActionChanged(DropTargetDragEvent dtde) {

    }

    public void drop(DropTargetDropEvent e) {
        try {
            DataFlavor stringFlavor = DataFlavor.stringFlavor;
            Transferable tr = e.getTransferable();

            TreePath path = this.getPathForLocation(e.getLocation().x, e
                    .getLocation().y);
            if (path == null) {
                e.rejectDrop();
                return;
            }
            FileNode node = (FileNode) path.getLastPathComponent();
            if (e.isDataFlavorSupported(DataFlavor.javaFileListFlavor)
                    && node.isDirectory()) {
                e.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
                System.out.println("file cp");
                List list = (List) (e.getTransferable()
                        .getTransferData(DataFlavor.javaFileListFlavor));
                Iterator iterator = list.iterator();
                File parent = node.getFile();
                while (iterator.hasNext()) {
                    File f = (File) iterator.next();
                    cp(f, new File(parent, f.getName()));
                }
                node.reexplore();
                e.dropComplete(true);
                this.updateUI();
            } else if (e.isDataFlavorSupported(stringFlavor)
                    && node.isDirectory()) {
                String filename = (String) tr.getTransferData(stringFlavor);
                if (filename.endsWith(".txt") || filename.endsWith(".java")
                        || filename.endsWith(".jsp")
                        || filename.endsWith(".html")
                        || filename.endsWith(".htm")) {
                    e.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
                    File f = new File(filename);
                    if (f.exists()) {
                        f.renameTo(new File(node.getFile(), f.getName()));
                        node.reexplore();
                        ((FileNode) sourceNode.getParent()).remove(sourceNode);
                        e.dropComplete(true);
                        this.updateUI();
                    } else {
                        e.rejectDrop();
                    }
                } else {
                    e.rejectDrop();
                }
            } else {
                e.rejectDrop();
            }
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } catch (UnsupportedFlavorException ufe) {
            ufe.printStackTrace();
        } finally {
            ghostImage = null;
            this.repaint();
        }
    }

    private void cp(File src, File dest) throws IOException {
        if (src.isDirectory()) {
            if (!dest.exists()) {
                boolean ret = dest.mkdir();
                if (ret == false)
                    return;
            }
            File[] fs = src.listFiles();
            for (int i = 0; i < fs.length; i++) {
                cp(fs[i], new File(dest, fs[i].getName()));
            }
            return;
        }
        byte[] buf = new byte[1024];
        FileInputStream in = new FileInputStream(src);
        FileOutputStream out = new FileOutputStream(dest);
        int len;
        try {
            while ((len = in.read(buf)) > 0) {
                out.write(buf, 0, len);
            }
        } finally {
            in.close();
            out.close();
        }
    }

    public void dragExit(DropTargetEvent dte) {

    }
}

class FileNode extends DefaultMutableTreeNode {
    private boolean explored = false;

    public FileNode(File file) {
        setUserObject(file);
    }

    public boolean getAllowsChildren() {
        return isDirectory();
    }

    public boolean isLeaf() {
        return !isDirectory();
    }

    public File getFile() {
        return (File) getUserObject();
    }

    public boolean isExplored() {
        return explored;
    }

    public boolean isDirectory() {
        File file = getFile();
        return file.isDirectory();
    }

    public String toString() {
        File file = (File) getUserObject();
        String filename = file.toString();
        int index = filename.lastIndexOf(File.separator);

        return (index != -1 && index != filename.length() - 1) ? filename
                .substring(index + 1) : filename;
    }

    public void explore() {
        if (!isDirectory())
            return;

        if (!isExplored()) {
            File file = getFile();
            File[] children = file.listFiles();

            for (int i = 0; i < children.length; ++i) {
                if (children[i].isDirectory())
                    add(new FileNode(children[i]));
            }
            for (int i = 0; i < children.length; ++i) {
                if (!children[i].isDirectory())
                    add(new FileNode(children[i]));
            }
            explored = true;
        }
    }

    public void reexplore() {
        this.removeAllChildren();
        explored = false;
        explore();
    }
}

使用方法示例:

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.dnd.DnDConstants;
import java.awt.dnd.DropTarget;
import java.awt.dnd.DropTargetDragEvent;
import java.awt.dnd.DropTargetDropEvent;
import java.awt.dnd.DropTargetEvent;
import java.awt.dnd.DropTargetListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;

import javax.swing.BorderFactory;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.UIManager;
import javax.swing.WindowConstants;
import javax.swing.filechooser.FileSystemView;
import javax.swing.text.Document;
import javax.swing.text.EditorKit;

public class Test extends JFrame implements DropTargetListener {
    private JEditorPane textPane = new JEditorPane();

    public Test() {
        super("Drag and Drop With Swing");

        new DropTarget(textPane, DnDConstants.ACTION_COPY_OR_MOVE, this);

        JSplitPane splitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
                createTreePanel(), createTextPanel());

        splitPane.setDividerLocation(250);
        splitPane.setOneTouchExpandable(true);

        getContentPane().add(splitPane, BorderLayout.CENTER);
    }

    public static void main(String args[]) {
       
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception e1) {
            e1.printStackTrace();
        }
        Test test = new Test();

        test.setBounds(300, 300, 850, 350);
        test.setVisible(true);
        test.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
        test.addWindowListener(new WindowAdapter() {
            public void windowClosed(WindowEvent e) {
                System.exit(0);
            }
        });
    }

    private JPanel createTreePanel() {
        JPanel treePanel = new JPanel();
        DragTree tree = new DragTree();

        treePanel.setLayout(new BorderLayout());
        treePanel.add(new JScrollPane(tree), BorderLayout.CENTER);
        treePanel.setBorder(BorderFactory
                .createTitledBorder("Drag source for filenames"));
       
        return treePanel;
    }

    private JPanel createTextPanel() {
        JPanel textPanel = new JPanel();

        textPanel.setLayout(new BorderLayout());
        textPanel.add(new JScrollPane(textPane), BorderLayout.CENTER);
        textPanel.setMinimumSize(new Dimension(375, 0));
        textPanel.setBorder(BorderFactory
                .createTitledBorder("Drop target for filenames"));

        return textPanel;
    }

    private void readFile(final String filename) {
        try {
            textPane.setPage(new File(filename).toURL());
        } catch (IOException e) {
            EditorKit kit = textPane.getEditorKit();
            Document document = textPane.getDocument();

            try {
                document.remove(0, document.getLength());
                kit.read(new FileReader(filename), document, 0);
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
    }

    public void drop(DropTargetDropEvent e) {
        try {
            DataFlavor stringFlavor = DataFlavor.stringFlavor;
            Transferable tr = e.getTransferable();

            if (e.isDataFlavorSupported(stringFlavor)) {
                String filename = (String) tr.getTransferData(stringFlavor);
                if (filename.endsWith(".txt")
                        || filename.endsWith(".java") ||
                        filename.endsWith(".jsp") || filename.endsWith(".html") || filename.endsWith(".htm")) {
                    e.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);
                    readFile(filename);
                    textPane.setCaretPosition(0);
                    e.dropComplete(true);
                } else {
                    e.rejectDrop();
                }
            }
            else {
                e.rejectDrop();
            }
        } catch (IOException ioe) {
            ioe.printStackTrace();
        } catch (UnsupportedFlavorException ufe) {
            ufe.printStackTrace();
        }
    }

    public void dragEnter(DropTargetDragEvent e) {
    }

    public void dragExit(DropTargetEvent e) {
    }

    public void dragOver(DropTargetDragEvent e) {
    }

    public void dropActionChanged(DropTargetDragEvent e) {
    }
}

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