java - 将文件从操作系统拖放到 Java 应用程序 (Swing)

Question

首先让我说我一直在阅读 drag'n drop tutorial以及在 SO 上提出的类似问题，但不幸的是，我对此事只会更加困惑。我想要实现的目标相对简单，所以我很惊讶它已经给我带来了这么多麻烦。我正在编写一个小型实用程序，它将一堆结果文件(自定义定义的 xml 类型)合并到一个大的制表符分隔的文本文件中。大多数功能已经编码，但我想为它制作一个像样的 GUI。

我想要的是能够以一种友好的方式将文件拖放到组件(例如 JTextArea)中(阅读:不是完整路径，而是一个小图标和姓名)。我也希望能够提供一个 JFileChooser 来浏览文件。然后我将按顺序解析文件以生成我想要的矩阵。

到目前为止，我所了解到的是框架已经存在，但是任何额外的功能都需要定制。我在 Netbeans 中创建了一个测试 GUI，并尝试将一堆文件拖到 JTextArea 上，但它们显示为文件路径，诚然，它看起来非常丑陋。

对于如何巧妙地解决(或阐明)此问题的任何提示和指导，我将不胜感激。请注意，我确实打算在多个不同的操作系统(Mac、Win 和 Linux)上使用该软件。

编辑:我目前的代码基于 Sun 教程中的示例之一，如下所示

import java.awt.datatransfer.*;
import java.awt.event.*;
import java.awt.*;
import java.io.*;
import javax.swing.*;
import javax.swing.UIManager.LookAndFeelInfo;
import javax.swing.border.TitledBorder;
import javax.swing.filechooser.FileNameExtensionFilter;
import javax.swing.text.*;

public class ConsolidatorDemo extends JPanel implements ActionListener {
    private static final long serialVersionUID = -4487732343062917781L;
    JFileChooser fc;
    JButton clear;
    JTextArea dropZone, console;
    JSplitPane childSplitPane, parentSplitPane;
    PrintStream ps;

  public ConsolidatorDemo() {
    super(new BorderLayout());

    fc = new JFileChooser();;
    fc.setMultiSelectionEnabled(true);
    fc.setDragEnabled(true);
    fc.setControlButtonsAreShown(false);
    fc.setFileSelectionMode(JFileChooser.FILES_ONLY);               


    JPanel fcPanel = new JPanel(new BorderLayout());
    fcPanel.add(fc, BorderLayout.CENTER);

    clear = new JButton("Clear All");
    clear.addActionListener(this);
    JPanel buttonPanel = new JPanel(new BorderLayout());
    buttonPanel.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
    buttonPanel.add(clear, BorderLayout.LINE_END);

    JPanel leftUpperPanel = new JPanel(new BorderLayout());
    leftUpperPanel.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
    leftUpperPanel.add(fcPanel, BorderLayout.CENTER);
    leftUpperPanel.add(buttonPanel, BorderLayout.PAGE_END);


    JScrollPane leftLowerPanel = new javax.swing.JScrollPane();
    leftLowerPanel.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
    dropZone = new JTextArea();
    dropZone.setColumns(20);
    dropZone.setLineWrap(true);
    dropZone.setRows(5);
    dropZone.setDragEnabled(true);
    dropZone.setDropMode(javax.swing.DropMode.INSERT);
    dropZone.setBorder(new TitledBorder("Selected files/folders"));
    leftLowerPanel.setViewportView(dropZone);

    childSplitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
            leftUpperPanel, leftLowerPanel);
    childSplitPane.setDividerLocation(400);
    childSplitPane.setPreferredSize(new Dimension(480, 650));

    console = new JTextArea();
    console.setColumns(40);
    console.setLineWrap(true);
    console.setBorder(new TitledBorder("Console"));

    parentSplitPane = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,
                    childSplitPane, console);
    parentSplitPane.setDividerLocation(480);
    parentSplitPane.setPreferredSize(new Dimension(800, 650));

    add(parentSplitPane, BorderLayout.CENTER);

}

public void setDefaultButton() {
    getRootPane().setDefaultButton(clear);
}

public void actionPerformed(ActionEvent e) {
    if (e.getSource() == clear) {
        dropZone.setText("");

    }
}

/**
 * Create the GUI and show it. For thread safety,
 * this method should be invoked from the
 * event-dispatching thread.
 */
private static void createAndShowGUI() {
    //Make sure we have nice window decorations.
    JFrame.setDefaultLookAndFeelDecorated(true);
    try {
      //UIManager.setLookAndFeel("de.javasoft.plaf.synthetica.SyntheticaBlackStarLookAndFeel");
        for (LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
            if ("Nimbus".equals(info.getName())) {
                UIManager.setLookAndFeel(info.getClassName());
                break;
            }
        }
    }catch (Exception e){
      e.printStackTrace();
    }

    //Create and set up the window.
    JFrame frame = new JFrame("Consolidator!");
    frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

    //Create and set up the menu bar and content pane.
    ConsolidatorDemo demo = new ConsolidatorDemo();
    demo.setOpaque(true); //content panes must be opaque
    frame.setContentPane(demo);

    //Display the window.
    frame.pack();
    frame.setVisible(true);
    demo.setDefaultButton();
}

public static void main(String[] args) {
    //Schedule a job for the event-dispatching thread:
    //creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });
}

Answer 1

这里有一个快速片段，用于将实际文件导入 JList(而不是将其字符串表示形式导入文本组件)并使用自定义渲染器很好地呈现它。它改编自 BasicDnD(在教程中):

    fileDropper = new JList(new DefaultListModel());
    fileDropper.setDragEnabled(true);
    leftLowerPanel.setViewportView(fileDropper);

    TransferHandler handler =   new TransferHandler() {

        @Override
        public boolean canImport(TransferHandler.TransferSupport info) {
            // we only import FileList
            if (!info.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                return false;
            }
            return true;
        }

        @Override
        public boolean importData(TransferHandler.TransferSupport info) {
            if (!info.isDrop()) {
                return false;
            }

            // Check for FileList flavor
            if (!info.isDataFlavorSupported(DataFlavor.javaFileListFlavor)) {
                displayDropLocation("List doesn't accept a drop of this type.");
                return false;
            }

            // Get the fileList that is being dropped.
            Transferable t = info.getTransferable();
            List<File> data;
            try {
                data = (List<File>)t.getTransferData(DataFlavor.javaFileListFlavor);
            } 
            catch (Exception e) { return false; }
            DefaultListModel model = (DefaultListModel) fileDropper.getModel();
            for (File file : data) {
                model.addElement(file);
            }
            return true;
        }

        private void displayDropLocation(String string) {
            System.out.println(string);
        }
    };
    fileDropper.setTransferHandler(handler);
    fileDropper.setCellRenderer(new DefaultListRenderer(
          StringValues.FILE_NAME, IconValues.FILE_ICON));

忍不住要显示 SwingX 渲染器配置 :-) 在核心 java 中，你会手动完成，比如

   class MyRenderer extends DefaultListCellRenderer {

        @Override
        public Component getListCellRendererComponent(...) {
            super.getList...
            if (value instanceof File) {
                setText(FileSystemView.getFileSystemView().getDisplayName(value);
                setIcon(FileSystemView.getFileSystemView().getSystemIcon(value);
            } 
            return this;
        }

   }