我想实现从某个目录(例如某人的硬盘驱动器)中拖放文件,但不知道该怎么做。我已经阅读了Java api,但它谈到了颜色选择器以及在列表之间进行拖放,但是如何将文件从计算机文件系统拖放到我的应用程序中。我尝试编写什么时候开始拖动,但似乎没有任何效果的transferhandler类和鼠标事件。现在,我回到设置JFileChooser的位置,以便启用拖动功能,但如何放置?

任何信息或指向正确方向的信息都将不胜感激。

  import javax.swing.*;

  import java.awt.BorderLayout;
 import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;

import javax.swing.BorderFactory;
import javax.swing.DefaultListModel;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFileChooser;
import javax.swing.JFrame;

import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
import javax.swing.filechooser.FileFilter;

 public class FileChooserDemo
 extends JPanel
 implements ActionListener
  {

JLabel selectedFileLabel;
 JList selectedFilesList;
 JLabel returnCodeLabel;

 public FileChooserDemo()
    {
 super();
 createContent();
 }


void initFrameContent()
    {
        JPanel closePanel = new JPanel();
        add(closePanel, BorderLayout.SOUTH);
}


 private void createContent()
    {
 setLayout(new BorderLayout());

        JPanel NorthPanel = new JPanel();

     JMenuBar menuBar = new JMenuBar();
        JMenu menu = new JMenu("File");
        JMenuItem quit = new JMenuItem("Quit");

        menuBar.add(menu);
        menu.add(quit);

        NorthPanel.add(menu,BorderLayout.NORTH);


  JPanel buttonPanel = new JPanel(new GridLayout(7,1 ));
  JButton openButton = new JButton("Open...");
  openButton.setActionCommand("OPEN");
  openButton.addActionListener(this);
 buttonPanel.add(openButton);

 JButton saveButton = new JButton("Save...");
 saveButton.setActionCommand("SAVE");
 saveButton.addActionListener(this);
 buttonPanel.add(saveButton);




  JButton delete = new JButton("Delete");
  delete.addActionListener(this);
  delete.setActionCommand("DELETE");
  buttonPanel.add(delete);

 add(buttonPanel, BorderLayout.WEST);



 // create a panel to display the selected file(s) and the return code
 JPanel displayPanel = new JPanel(new BorderLayout());
 selectedFileLabel = new JLabel("-");

 selectedFileLabel.setBorder(BorderFactory.createTitledBorder
 ("Selected File/Directory   "));

 displayPanel.add(selectedFileLabel, BorderLayout.NORTH);

 selectedFilesList = new JList();
 JScrollPane sp = new JScrollPane(selectedFilesList);
 sp.setBorder(BorderFactory.createTitledBorder("Selected Files "));
 MouseListener listener = new MouseAdapter()
 {
   public void mousePressed(MouseEvent me)
   {
       JComponent comp = (JComponent) me.getSource();
       TransferHandler handler = comp.getTransferHandler();
       handler.exportAsDrag(comp, me, TransferHandler.MOVE);
   }
 };
 selectedFilesList.addMouseListener(listener);

 displayPanel.add(sp);

 returnCodeLabel = new JLabel("");
 returnCodeLabel.setBorder(BorderFactory.createTitledBorder("Return Code"));
 displayPanel.add(returnCodeLabel, BorderLayout.SOUTH);

 add(displayPanel);
}


 public void actionPerformed(ActionEvent e)
    {
          int option = 0;
 File selectedFile = null;
 File[] selectedFiles = new File[0];

 if (e.getActionCommand().equals("CLOSE"))
      {
   System.exit(0);
 }
 else if (e.getActionCommand().equals("OPEN"))
        {
     JFileChooser chooser = new JFileChooser();
        chooser.setDragEnabled(true);
        chooser.setMultiSelectionEnabled(true);
     option = chooser.showOpenDialog(this);
     selectedFiles = chooser.getSelectedFiles();
   }
 else if (e.getActionCommand().equals("SAVE"))
        {
     JFileChooser chooser = new JFileChooser();
     option = chooser.showSaveDialog(this);
     selectedFiles = chooser.getSelectedFiles();
   }

 // display the selection and return code
 if (selectedFile != null)
   selectedFileLabel.setText(selectedFile.toString());
 else
   selectedFileLabel.setText("null");
 DefaultListModel listModel = new DefaultListModel();
 for (int i =0; i < selectedFiles.length; i++)
   listModel.addElement(selectedFiles[i]);

 selectedFilesList.setModel(listModel);
 returnCodeLabel.setText(Integer.toString(option));
 }

 public static void main(String[] args)
    {
 SwingUtilities.invokeLater
 (new Runnable()
       {
    public void run()
         {
      FileChooserDemo app = new FileChooserDemo();
      app.initFrameContent();
      JFrame frame = new JFrame("LoquetUP");
      frame.getContentPane().add(app);
         frame.setDefaultCloseOperation(3);
         frame.setSize(600,400);
         frame.setResizable(false);
         frame.setLocationRelativeTo(null);

      //frame.pack();
      frame.setVisible(true);
    }
  });
 }

}

最佳答案

这是我的想法。在此示例中,我使用了“传统”拖放API。它还有一些额外的“绘画”调整,只是为了炫耀您可能执行的操作。

此示例不扫描放置在其上的文件夹,因此任何文件夹都只会注册为一个文件,但是我敢肯定您可以解决它

public class TestDragNDropFiles {

    public static void main(String[] args) {
        new TestDragNDropFiles();
    }

    public TestDragNDropFiles() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new DropPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class DropPane extends JPanel {

        private DropTarget dropTarget;
        private DropTargetHandler dropTargetHandler;
        private Point dragPoint;

        private boolean dragOver = false;
        private BufferedImage target;

        private JLabel message;

        public DropPane() {
            try {
                target = ImageIO.read(new File("target.png"));
            } catch (IOException ex) {
                ex.printStackTrace();
            }

            setLayout(new GridBagLayout());
            message = new JLabel();
            message.setFont(message.getFont().deriveFont(Font.BOLD, 24));
            add(message);

        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(400, 400);
        }

        protected DropTarget getMyDropTarget() {
            if (dropTarget == null) {
                dropTarget = new DropTarget(this, DnDConstants.ACTION_COPY_OR_MOVE, null);
            }
            return dropTarget;
        }

        protected DropTargetHandler getDropTargetHandler() {
            if (dropTargetHandler == null) {
                dropTargetHandler = new DropTargetHandler();
            }
            return dropTargetHandler;
        }

        @Override
        public void addNotify() {
            super.addNotify();
            try {
                getMyDropTarget().addDropTargetListener(getDropTargetHandler());
            } catch (TooManyListenersException ex) {
                ex.printStackTrace();
            }
        }

        @Override
        public void removeNotify() {
            super.removeNotify();
            getMyDropTarget().removeDropTargetListener(getDropTargetHandler());
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (dragOver) {
                Graphics2D g2d = (Graphics2D) g.create();
                g2d.setColor(new Color(0, 255, 0, 64));
                g2d.fill(new Rectangle(getWidth(), getHeight()));
                if (dragPoint != null && target != null) {
                    int x = dragPoint.x - 12;
                    int y = dragPoint.y - 12;
                    g2d.drawImage(target, x, y, this);
                }
                g2d.dispose();
            }
        }

        protected void importFiles(final List files) {
            Runnable run = new Runnable() {
                @Override
                public void run() {
                    message.setText("You dropped " + files.size() + " files");
                }
            };
            SwingUtilities.invokeLater(run);
        }

        protected class DropTargetHandler implements DropTargetListener {

            protected void processDrag(DropTargetDragEvent dtde) {
                if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                    dtde.acceptDrag(DnDConstants.ACTION_COPY);
                } else {
                    dtde.rejectDrag();
                }
            }

            @Override
            public void dragEnter(DropTargetDragEvent dtde) {
                processDrag(dtde);
                SwingUtilities.invokeLater(new DragUpdate(true, dtde.getLocation()));
                repaint();
            }

            @Override
            public void dragOver(DropTargetDragEvent dtde) {
                processDrag(dtde);
                SwingUtilities.invokeLater(new DragUpdate(true, dtde.getLocation()));
                repaint();
            }

            @Override
            public void dropActionChanged(DropTargetDragEvent dtde) {
            }

            @Override
            public void dragExit(DropTargetEvent dte) {
                SwingUtilities.invokeLater(new DragUpdate(false, null));
                repaint();
            }

            @Override
            public void drop(DropTargetDropEvent dtde) {

                SwingUtilities.invokeLater(new DragUpdate(false, null));

                Transferable transferable = dtde.getTransferable();
                if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                    dtde.acceptDrop(dtde.getDropAction());
                    try {

                        List transferData = (List) transferable.getTransferData(DataFlavor.javaFileListFlavor);
                        if (transferData != null && transferData.size() > 0) {
                            importFiles(transferData);
                            dtde.dropComplete(true);
                        }

                    } catch (Exception ex) {
                        ex.printStackTrace();
                    }
                } else {
                    dtde.rejectDrop();
                }
            }
        }

        public class DragUpdate implements Runnable {

            private boolean dragOver;
            private Point dragPoint;

            public DragUpdate(boolean dragOver, Point dragPoint) {
                this.dragOver = dragOver;
                this.dragPoint = dragPoint;
            }

            @Override
            public void run() {
                DropPane.this.dragOver = dragOver;
                DropPane.this.dragPoint = dragPoint;
                DropPane.this.repaint();
            }
        }

    }
}

10-06 06:06
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