关于JAVA树,该怎么处理

   /**       * 在光标退出放置组件的显示区时发生       * @param e DragSourceEvent       */      public void dragExit(DragSourceEvent e) {}         /**       * 在光标进入放置组件显示区之后移动时调用       * @param e DragSourceDragEvent       */      public void dragOver(DragSourceDragEvent e) {}         /**       * 选择放置操作的修饰键的状态变化       * @param e DragSourceDragEvent       */      public void dropActionChanged(DragSourceDragEvent e) {}         /**       *放置发生并调用DropTargetListener的drop()方法后，调用dragDropEnd()方法，       * 告诉拖动源放置已经完成       * @param e DragSourceDropEvent       */      public void dragDropEnd(DragSourceDropEvent e) {           //getDropSuccess()对应DropTargetListener的drop()方法调用dropcomplete()时指目标指定的值           //getDropAction()对应DropTargetListener的drop()方法调用acceptDrop()时指定的操作           if (!e.getDropSuccess()||e.getDropAction()!= DnDConstants.ACTION_MOVE) {               return;           }             DragSourceContext context = e.getDragSourceContext();           Object comp = context.getComponent();           if (comp==null||!(comp instanceof JTree)) {               return ;           }           DefaultMutableTreeNode dragTreeNode = getDragTreeNode();                      if (dragTreeNode!=null) {               ((DefaultTreeModel) tree.getModel()).removeNodeFromParent(dragTreeNode);               //设置拖动的树节点为空               setDragTreeNode(null);           }         }   }             public static void main(String[] args) {          new Frame1().setVisible(true);      }   }         class Frame1_jButton2_actionAdapter implements ActionListener {       private Frame1 adaptee;       Frame1_jButton2_actionAdapter(Frame1 adaptee) {           this.adaptee = adaptee;       }         public void actionPerformed(ActionEvent e) {           adaptee.jButton2_actionPerformed(e);       }   }       class Frame1_jButton1_actionAdapter implements ActionListener {       private Frame1 adaptee;       Frame1_jButton1_actionAdapter(Frame1 adaptee) {           this.adaptee = adaptee;       }         public void actionPerformed(ActionEvent e) {           adaptee.jButton1_actionPerformed(e);       }   }
------解决方案--------------------
DragAndDropDropTargetListener.java
Java code
package tree;     import java.awt.Component;   import java.awt.datatransfer.Transferable;   import java.awt.dnd.*;     import javax.swing.JTree;   import javax.swing.tree.*;     //* Drop Target Listener */   public class DragAndDropDropTargetListener implements DropTargetListener {         //e.rejectDrop()只可以在dragEnter()、dragOver()和dropActionChanged()中调用，不能在drop()中调用         /**       * 在光标进入放置组件的显示区时调用       * @param e DropTargetDragEvent       */      public void dragEnter(DropTargetDragEvent e) {       }         /**       * 在光标进入放置组件显示区之后移动时调用       * @param e DropTargetDragEvent       */      public void dragOver(DropTargetDragEvent e) {       }         /**       * 选择放置操作的修饰键的状态变化       * @param e DropTargetDragEvent       */      public void dropActionChanged(DropTargetDragEvent e) {}         /**       * 在光标退出放置组件的显示区时发生       * @param e DropTargetEvent       */      public void dragExit(DropTargetEvent e) {}           /**       * 在发生放置时调用，负责接受或拒绝放置请求和处理放置的数据       * @param e DropTargetDropEvent       */      public void drop(DropTargetDropEvent e) {           //获取要传递的数据           Transferable transfer = e.getTransferable();           DefaultMutableTreeNode dragSource = null;           //是否支持树节点数据的传递           if (transfer.isDataFlavorSupported(DragAndDropTransferable.TREENODE_FLAVOR)) {               try {                   //设置接受移动的操作                   e.acceptDrop(DnDConstants.ACTION_MOVE);                   //获取传递的数据                   dragSource = (DefaultMutableTreeNode) transfer.getTransferData(                           DragAndDropTransferable.TREENODE_FLAVOR);               } catch (Exception ex) {                   ex.printStackTrace();               }           }           if (dragSource == null) { //拖动的数据源为空则退出               //放置不成功               e.dropComplete(false);               return;           }           //获取dropTo对象           DropTarget dt = (DropTarget) e.getSource();           Component comp = dt.getComponent();           if (!(comp instanceof JTree)) {               //放置不成功               e.dropComplete(false);               return;           }           JTree jtr = (JTree) comp;           TreePath treePath = jtr.getPathForLocation(e.getLocation().x,e.getLocation().y);           if (treePath==null) {                //放置不成功               e.dropComplete(false);               return;           }           DefaultMutableTreeNode treeNode = (DefaultMutableTreeNode) treePath.getLastPathComponent();           if (!isCanDrop(dragSource,treeNode,jtr)) {               //放置不成功               e.dropComplete(false);               return;           }             //把节点添加到当前树节点下           treeNode.add(dragSource);           //更新树节点           ((DefaultTreeModel)jtr.getModel()).reload(treeNode);             //设置放置成功           e.dropComplete(true);       }         /**       * 判断是否可以放置操作       * @param dragTreeNode DefaultMutableTreeNode 拖动源的树节点       * @param dropTreeNode DefaultMutableTreeNode 放置目标的树节点       * @return boolean       */      public boolean isCanDrop(DefaultMutableTreeNode dragTreeNode,                                DefaultMutableTreeNode dropTreeNode, JTree jtr) {           if (dragTreeNode == null) { //拖动源为空则退出               return false;           }           //设置放置目标为空时不可放置           if (dropTreeNode == null ) {               return false;           }           //放置目标是拖动源则退出           if (dragTreeNode==dropTreeNode) {            return false;           }          TreePath dragPath = new TreePath (((DefaultTreeModel )jtr.getModel()).getPathToRoot(dragTreeNode));          TreePath dropPath = new TreePath (((DefaultTreeModel )jtr.getModel()).getPathToRoot(dropTreeNode));          String strDragPath = dragPath.toString();          String strDropPath = dropPath.toString();          String subDragPath = strDragPath.substring(0,strDragPath.length()-1);            if (strDropPath.startsWith(subDragPath)) {//放置目标是拖动源的子孙节点              return false;          }          if ( dragPath.getParentPath().toString().equals(strDropPath)) {//放置目标是拖动源的父节点              return false;          }            //放置目标是拖动源的父节点则退出          if (dragTreeNode.getParent().equals(dropTreeNode)) {              return false;          }            return true;       }   }