dndtree.java

JTREE的例子

package dragTree;

import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.dnd.*;
import java.awt.dnd.peer.*;
import java.awt.event.*;
import java.awt.datatransfer.*;
import java.io.*;

import util3.DMTreeNode;

public class DnDTree extends JTree implements DragGestureListener{
  private TreePath dragingTP;
  private DragSource dragSource;
  private DragSourceImpl dsi=new DragSourceImpl();
  private DMTreeNode currenParent=null;
  private boolean dropAble=false;

  public DnDTree(DMTreeNode dmTreeNode) {
    super(dmTreeNode);
    currenParent=(DMTreeNode)
      this.getPathForRow(0).getLastPathComponent();
    dragSource=DragSource.getDefaultDragSource();
    DragGestureRecognizer dgr=dragSource.createDefaultDragGestureRecognizer(
        this,DnDConstants.ACTION_COPY_OR_MOVE,this);
    dgr.setSourceActions(dgr.getSourceActions() & ~InputEvent.BUTTON3_MASK);

    DropTarget dropTarget = new DropTarget(this,new DropTargetImpl());
  }

  public void dragGestureRecognized(DragGestureEvent e){
    Point p=e.getDragOrigin();
    Cursor cursor=null;
    try{
      dragingTP = getPathForLocation(p.x,p.y);
    }catch(NullPointerException npe){return;}

    if(dragingTP!=null){//System.out.println("here");
      Transferable transferable = (Transferable)
          (((DMTreeNode)dragingTP.getLastPathComponent()).getUserObject());
      cursor = DragSource.DefaultCopyNoDrop;
      int action = e.getDragAction();
      if (action == DnDConstants.ACTION_MOVE){
        this.dropAble=true;
        cursor = DragSource.DefaultMoveDrop;
      }
      else if(action==DnDConstants.ACTION_COPY){
        if(!((DMTreeNode)dragingTP.getLastPathComponent()).isLeaf()){
          this.dropAble=false;
          cursor=DragSource.DefaultCopyNoDrop;
        }
        else{
          this.dropAble=true;
          cursor=DragSource.DefaultCopyDrop;
        }
      }
      dragSource.startDrag(e, cursor, transferable, dsi);
    }
  }

  public void addNode(String name){
    TransferableImpl ti=new TransferableImpl(name);
    DMTreeNode tn=null;
    this.currenParent.add(tn=new DMTreeNode(ti));
    this.currenParent=tn;
  }

  class DropTargetImpl extends DropTargetAdapter{
    public void dragOver(DropTargetDragEvent e) {
    }

    public void drop(DropTargetDropEvent e) {//System.out.println("here0");
      try{
        Transferable tr = e.getTransferable();
        if (!tr.isDataFlavorSupported(TransferableImpl.TRAN_FLAVOR)) e.rejectDrop();
        TransferableImpl transfer = (TransferableImpl)tr.getTransferData(TransferableImpl.TRAN_FLAVOR);
        Point p=e.getLocation();
        TreePath toTP = getPathForLocation(p.x, p.y);
        //whether it can be droped here?
        if(!(isDropOK(dragingTP,toTP) && dropAble)) return;

        boolean isCopyDrop = DnDConstants.ACTION_COPY==e.getDropAction();
        DMTreeNode toParent=(DMTreeNode)toTP.getLastPathComponent();
        DMTreeNode dragingTN=null;
        DMTreeNode oldParent=null;
        int oldIndex=0;
        int newIndex=0;
        if(isCopyDrop){
          TransferableImpl tranCopy=transfer.copy();
          dragingTN=new DMTreeNode(tranCopy);
        }else{
          oldParent=(DMTreeNode)dragingTP.getParentPath().getLastPathComponent();
          DMTreeNode tn=(DMTreeNode)dragingTP.getLastPathComponent();
          oldIndex=oldParent.getIndex(tn);
          newIndex=toParent.getParent().getIndex(toParent);
          oldParent.remove(tn);
          dragingTN=tn;
        }
        if(!toParent.isLeaf()){
          toParent.add(dragingTN);
        }else{
          DMTreeNode parent=(DMTreeNode)toParent.getParent();
          int index=parent.getIndex(toParent);
          //System.out.println(parent.getChildCount());
          if(parent==oldParent && newIndex>oldIndex)index++;
          parent.insert(dragingTN,index);
        }
        DnDTree.this.updateUI();
      }catch(Exception ex){
        ex.printStackTrace();
        e.rejectDrop();
      }
    }

    boolean isDropOK(TreePath fromTP,TreePath toTP){
      if(fromTP==null || toTP==null) {/*System.out.println("cant0");*/ return false;}
      if(fromTP.equals(toTP)) {/*System.out.println("cant1");*/ return false;}
      if(fromTP.isDescendant(toTP)) {/*System.out.println("cant2");*/ return false;}
      return true;
    }
  }

  class DragSourceImpl extends DragSourceAdapter{
  }
}