从JTree Transferable TransferHandler

Question

我正在探索如何实施Copy＆amp; Paste的{​​{1}}。

因为，我希望像JTree这样的DefaultMutableTreeNode复制粘贴到Sublime Text等其他应用程序中。

我正在查看代码，以便查看how copy & paste is implemented以及如何使用drag and drop in JTree。

我的第一个问题是，toString() DefaultMutableTreeNode JTree之间的复制和粘贴必须经过测试，之后如何从剪贴板粘贴到另一个应用程序，但我的代码无效并且不知道为什么失败了，我需要解决。

注意：抱歉我的代码有点长，因为如果我只放一个代码片段就会无效。对我来说，这里的所有代码都需要进行测试。

这是我的代码：

import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.event.ActionEvent;
import java.util.*;
import javax.swing.*;
import javax.swing.tree.*;

public class JTreeTransferHandler extends JFrame {

  public JTreeTransferHandler() {
    initiate();
  }

  private void initiate() {
    setTitle("Copy from JTree");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(400,400);
    setLocation(200,200);
    setVisible(true);

    DefaultMutableTreeNode root = new DefaultMutableTreeNode("Root");
    DefaultMutableTreeNode vegetableNode = new DefaultMutableTreeNode("Vegetables");
    vegetableNode.add(new DefaultMutableTreeNode("Capsicum"));
    vegetableNode.add(new DefaultMutableTreeNode("Carrot"));

    DefaultMutableTreeNode fruitNode = new DefaultMutableTreeNode("Fruits");
    fruitNode.add(new DefaultMutableTreeNode("Mango"));
    fruitNode.add(new DefaultMutableTreeNode("Apple"));
    root.add(vegetableNode);
    root.add(fruitNode);

    JTree tree = new JTree(root);

    TreeTransferHandler treeTransferHandler = new TreeTransferHandler();
    tree.setTransferHandler(treeTransferHandler);

    Clipboard clipboard = this.getToolkit().getSystemClipboard();

    JButton copy = new JButton("Copy");
    copy.addActionListener((ActionEvent e) -> {
      TransferHandler handler = tree.getTransferHandler();
      handler.exportToClipboard(tree, clipboard, TransferHandler.COPY);
    });

    JButton paste = new JButton("Paste");
    paste.addActionListener((ActionEvent e) -> {
      Transferable clipData = clipboard.getContents(clipboard);
      if (clipData != null) {
        if (clipData.isDataFlavorSupported(treeTransferHandler.nodesFlavor)) {
          TransferHandler handler = tree.getTransferHandler();
          handler.importData(tree, clipData);
        }
      }
    });

    JPanel buttonsPanel = new JPanel();
    buttonsPanel.add(copy);
    buttonsPanel.add(paste);

    add(new JScrollPane(tree), BorderLayout.CENTER);
    add(buttonsPanel, BorderLayout.SOUTH);
  }

  public static void main(String[] args) {
    SwingUtilities.invokeLater(() -> {
      JTreeTransferHandler jTreeTransferHandler = new JTreeTransferHandler();
    });
  }     
}

class TreeTransferHandler extends TransferHandler {
  DataFlavor nodesFlavor;
  DataFlavor[] flavors = new DataFlavor[1];
  DefaultMutableTreeNode[] nodesToRemove;

  public TreeTransferHandler() {
    try {
      String mimeType = DataFlavor.javaJVMLocalObjectMimeType + ";class=\"" +
          DefaultMutableTreeNode[].class.getName() + "\"";
      nodesFlavor = new DataFlavor(mimeType);
      flavors[0] = nodesFlavor;
    } catch(ClassNotFoundException e) {
      System.out.println("ClassNotFound: " + e.getMessage());
    }
  }

  //TransferHandler
  @Override public int getSourceActions(JComponent c) {
    return TransferHandler.COPY;
  }

  //TransferHandler
  @Override public boolean canImport(JComponent comp, DataFlavor flavor[]) {
    for (int i = 0, n = flavor.length; i < n; i++) {
      for (int j = 0, m = flavors.length; j < m; j++) {
        if (flavor[i].equals(flavors[j])) {
          return true;
        }
      }
    }
    return false;
  }

  //TransferHandler
  @Override protected Transferable createTransferable(JComponent c) {
    JTree tree = (JTree) c;
    TreePath[] paths = tree.getSelectionPaths();
    if (paths != null) {
      List<DefaultMutableTreeNode> copies = new ArrayList<>();
      List<DefaultMutableTreeNode> toRemove = new ArrayList<>();
      DefaultMutableTreeNode node = 
          (DefaultMutableTreeNode) paths[0].getLastPathComponent();
      DefaultMutableTreeNode copy = copy(node);
      copies.add(copy);
      toRemove.add(node);
      for (int i = 1; i < paths.length; i++) {
        DefaultMutableTreeNode next = 
            (DefaultMutableTreeNode) paths[i].getLastPathComponent();
        // Do not allow higher level nodes to be added to list.
        if (next.getLevel() < node.getLevel()) {
          break;
        } else if (next.getLevel() > node.getLevel()) {  // child node
          copy.add(copy(next));
          // node already contains child
        } else {                                        // sibling
          copies.add(copy(next));
          toRemove.add(next);
        }
      }
      DefaultMutableTreeNode[] nodes = 
          copies.toArray(new DefaultMutableTreeNode[copies.size()]);
      nodesToRemove = 
          toRemove.toArray(new DefaultMutableTreeNode[toRemove.size()]);
      return new NodesTransferable(nodes);
    }
    return null;
  }
  /** Defensive copy used in createTransferable. */
  private DefaultMutableTreeNode copy(TreeNode node) {
    return new DefaultMutableTreeNode(node);
  }

  //TransferHandler
  @Override public boolean importData(TransferHandler.TransferSupport support) {
    if (!canImport(support)) {
      return false;
    }
    // Extract transfer data.
    DefaultMutableTreeNode[] nodes = null;
    try {
      Transferable t = support.getTransferable();
      nodes = (DefaultMutableTreeNode[]) t.getTransferData(nodesFlavor);
    } catch (UnsupportedFlavorException ufe) {
      System.out.println("UnsupportedFlavor: " + ufe.getMessage());
    } catch (java.io.IOException ioe) {
      System.out.println("I/O error: " + ioe.getMessage());
    }
    // Get drop location info.
    JTree.DropLocation dl
        = (JTree.DropLocation) support.getDropLocation();
    int childIndex = dl.getChildIndex();
    TreePath dest = dl.getPath();
    DefaultMutableTreeNode parent
        = (DefaultMutableTreeNode) dest.getLastPathComponent();
    JTree tree = (JTree) support.getComponent();
    DefaultTreeModel model = (DefaultTreeModel) tree.getModel();
    // Configure for drop mode.
    int index = childIndex;    // DropMode.INSERT
    if (childIndex == -1) {     // DropMode.ON
      index = parent.getChildCount();
    }
    // Add data to model.
    for (int i = 0; i < nodes.length; i++) {
      model.insertNodeInto(nodes[i], parent, index++);
    }
    return true;
  }

  //TransferHandler
  public boolean importData(JComponent comp, Transferable t) {
    // Extract transfer data.
    DefaultMutableTreeNode[] nodes;
    try {
      nodes = (DefaultMutableTreeNode[]) t.getTransferData(nodesFlavor);
      if (comp instanceof JTree) {
        JTree tree = (JTree)comp;
        DefaultTreeModel model = (DefaultTreeModel) tree.getModel();

        JTree.DropLocation dl = tree.getDropLocation();
        int childIndex = dl.getChildIndex();
        TreePath dest = dl.getPath();
        DefaultMutableTreeNode parent = 
            (DefaultMutableTreeNode)dest.getLastPathComponent();
        // Configure for drop mode.
        int index = childIndex;    // DropMode.INSERT
        if (childIndex == -1) {     // DropMode.ON
          index = parent.getChildCount();
        }
        // Add data to model.
        for (DefaultMutableTreeNode node : nodes) {
          model.insertNodeInto(node, parent, index++);
        }
        return true;
      }
    } catch (UnsupportedFlavorException ufe) {
      System.out.println("UnsupportedFlavor: " + ufe.getMessage());
    } catch (java.io.IOException ioe) {
      System.out.println("I/O error: " + ioe.getMessage());
    }
    return false;
  }

  public class NodesTransferable implements Transferable {
    DefaultMutableTreeNode[] nodes;

    public NodesTransferable(DefaultMutableTreeNode[] nodes) {
      this.nodes = nodes;
    }

    //Transferable
    @Override public Object getTransferData(DataFlavor flavor)  {
      if(!isDataFlavorSupported(flavor)) {
        return false;
      }
      return nodes;
    }

    //Transferable
    @Override public DataFlavor[] getTransferDataFlavors() {
      return flavors;
    }

    //Transferable
    @Override public boolean isDataFlavorSupported(DataFlavor flavor) {
      return flavor.equals(nodesFlavor);
    }
  }
}

Answer 1

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TransferHandler.TransferSupport#isDrop()方法返回false，因此在此处切换它似乎工作正常。

Clipboard

<强> JTreeTransferHandler2.java

// Get drop location info.
int childIndex;
TreePath dest;
if (support.isDrop()) {
  JTree.DropLocation dl = (JTree.DropLocation) support.getDropLocation();
  childIndex = dl.getChildIndex();
  dest = dl.getPath();
} else {
  childIndex = -1;
  JTree tree = (JTree) support.getComponent();
  dest = tree.getSelectionPath();
}