使用拖放对列表框进行重新排序代码,Java代码库,德仔网

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【Java】使用拖放对列表框进行重新排序
作者:DDT / 发布于2012/6/12/ 524
使用拖放对列表框进行重新排序
<div>public class ReorderableJList extends JList 
 implements DragSourceListener, DropTargetListener, DragGestureListener {

 static DataFlavor localObjectFlavor;
 static {
 try {
 localObjectFlavor =
 new DataFlavor (DataFlavor.javaJVMLocalObjectMimeType);
 } catch (ClassNotFoundException cnfe) { cnfe.printStackTrace(); } 
 } 
 static DataFlavor[] supportedFlavors = { localObjectFlavor }; 
 DragSource dragSource; 
 DropTarget dropTarget; 
 Object dropTargetCell; 
 int draggedIndex = -1;</div>
<div> public ReorderableJList () {
 super();
 setCellRenderer (new ReorderableListCellRenderer());
 setModel (new DefaultListModel());
 dragSource = new DragSource();
 DragGestureRecognizer dgr =
 dragSource.createDefaultDragGestureRecognizer (this,
 DnDConstants.ACTION_MOVE,
 this);
 dropTarget = new DropTarget (this, this);
 }
<div> // DragGestureListener
 public void dragGestureRecognized (DragGestureEvent dge) {
 System.out.println ("dragGestureRecognized");
 // find object at this x,y
 Point clickPoint = dge.getDragOrigin();
 int index = locationToIndex(clickPoint);
 if (index == -1)
 return;
 Object target = getModel().getElementAt(index);
 Transferable trans = new RJLTransferable (target);
 draggedIndex = index;
 dragSource.startDrag (dge,Cursor.getDefaultCursor(),
 trans, this);
 }
 // DragSourceListener events
 public void dragDropEnd (DragSourceDropEvent dsde) {
 System.out.println ("dragDropEnd()");
 dropTargetCell = null;
 draggedIndex = -1;
 repaint();
 }
public void dragEnter (DragSourceDragEvent dsde) {}
 public void dragExit (DragSourceEvent dse) {}
 public void dragOver (DragSourceDragEvent dsde) {}
 public void dropActionChanged (DragSourceDragEvent dsde) {}
 // DropTargetListener events
 public void dragEnter (DropTargetDragEvent dtde) {
 System.out.println ("dragEnter");
 if (dtde.getSource() != dropTarget)
 dtde.rejectDrag();
 else {
 dtde.acceptDrag(DnDConstants.ACTION_COPY_OR_MOVE);
 System.out.println ("accepted dragEnter");
 }
 }
 public void dragExit (DropTargetEvent dte) {}
public void dragOver (DropTargetDragEvent dtde) { 
 // figure out which cell it's over, no drag to self 
 if (dtde.getSource() != dropTarget)
 dtde.rejectDrag();
 Point dragPoint = dtde.getLocation();
 int index = locationToIndex (dragPoint);
 if (index == -1)
 dropTargetCell = null; 
 else 
 dropTargetCell = getModel().getElementAt(index); 
 repaint(); 
}
<div>public void drop (DropTargetDropEvent dtde) { 
 System.out.println ("drop()!"); 
 if (dtde.getSource() != dropTarget) {
 System.out.println ("rejecting for bad source (" +
 dtde.getSource().getClass().getName() + ")"); 
 dtde.rejectDrop(); 
 return;
 }
 Point dropPoint = dtde.getLocation();
 int index = locationToIndex (dropPoint);
 System.out.println ("drop index is " + index);
 boolean dropped = false;
 try {
 if ((index == -1) || (index == draggedIndex)) {
 System.out.println ("dropped onto self");
 dtde.rejectDrop();
 return;
 }
 dtde.acceptDrop (DnDConstants.ACTION_MOVE);
 System.out.println ("accepted");
 Object dragged =
 dtde.getTransferable().getTransferData(localObjectFlavor);
 // move items - note that indicies for insert will 
 // change if [removed] source was before target 
 System.out.println ("drop " + draggedIndex + " to " + index);
 boolean sourceBeforeTarget = (draggedIndex < index); 
 System.out.println ("source is" +
 (sourceBeforeTarget ? "" : " not") +
 " before target");
 System.out.println ("insert at " +
 (sourceBeforeTarget ? index-1 : index));
 DefaultListModel mod = (DefaultListModel) getModel(); 
 mod.remove (draggedIndex); 
 mod.add ((sourceBeforeTarget ? index-1 : index), dragged); 
 dropped = true;
 } catch (Exception e) {
 e.printStackTrace();
 }
 dtde.dropComplete (dropped);
}
<div> public void dropActionChanged (DropTargetDragEvent dtde) {}

public static void main (String[] args) { 
 JList list = new ReorderableJList (); 
 DefaultListModel defModel = new DefaultListModel(); 
 list.setModel (defModel); 
 String[] listItems = {
 "Chris", "Joshua", "Daniel", "Michael",
 "Don", "Kimi", "Kelly", "Keagan"
 };
 Iterator it = Arrays.asList(listItems).iterator();
 while (it.hasNext())
 defModel.addElement (it.next());
 // show list
 JScrollPane scroller =
 new JScrollPane (list, 
 ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS, 
 ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
 JFrame frame = new JFrame ("Checkbox JList");
 frame.getContentPane().add (scroller);
 frame.pack();
 frame.setVisible(true);
}
<div>class RJLTransferable implements Transferable { 
 Object object; 
 public RJLTransferable (Object o) {
 object = o;
 }
 public Object getTransferData(DataFlavor df)
 throws UnsupportedFlavorException, IOException {
 if (isDataFlavorSupported (df))
 return object;
 else
 throw new UnsupportedFlavorException(df);
 }
 public boolean isDataFlavorSupported (DataFlavor df) {
 return (df.equals (localObjectFlavor));
 }
 public DataFlavor[] getTransferDataFlavors () {
 return supportedFlavors; } 
}
<div>class ReorderableListCellRenderer 
 extends DefaultListCellRenderer { 
 boolean isTargetCell; 
 boolean isLastItem; 
 public ReorderableListCellRenderer() {
 super();
 }
 public Component getListCellRendererComponent (JList list,
 Object value, 
 int index, 
 boolean isSelected, boolean hasFocus) {
 isTargetCell = (value == dropTargetCell);
 isLastItem = (index == list.getModel().getSize()-1);
 boolean showSelected = isSelected &
 (dropTargetCell == null);
 return super.getListCellRendererComponent (list, value, 
 index, showSelected, 
 hasFocus);
 }
 public void paintComponent (Graphics g) {
 super.paintComponent(g);
 if (isTargetCell) {
 g.setColor(Color.black); 
 g.drawLine (0, 0, getSize().width, 0); 
 } 
 } 
}
<div>}
</div>
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