java swing 树型结构

package swing_advance;import javax.swing.*;import javax.swing.event.TreeSelectionEvent;import javax.swing.event.TreeSelectionListener;import javax.swing.tree.*;import java.awt.*;import java.beans.PropertyChangeListener;public class TreeSelection extends JFrame {public TreeSelection(){Container c=getContentPane();setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);    setSize(200,300);                    DefaultMutableTreeNode root = new DefaultMutableTreeNode("根节点");    DefaultMutableTreeNode child1 = new DefaultMutableTreeNode("子节点A");    DefaultMutableTreeNode child2 = new DefaultMutableTreeNode("子节点B");        DefaultMutableTreeNode childchild1 = new DefaultMutableTreeNode("子节点AA",false);    DefaultMutableTreeNode childchild2 = new DefaultMutableTreeNode("子节点BB",false);        root.add(child1);    root.add(child2);    child1.add(childchild1);    child2.add(childchild2);    DefaultTreeModel dt=new DefaultTreeModel(root,true);    final JTree jt = new JTree(dt);        c.add(jt,BorderLayout.WEST);    setVisible(true);        TreeSelectionModel treeselect = jt.getSelectionModel();    treeselect.setSelectionMode(TreeSelectionModel.CONTIGUOUS_TREE_SELECTION);        jt.addTreeSelectionListener(new TreeSelectionListener() {@Overridepublic void valueChanged(TreeSelectionEvent e) {// TODO Auto-generated method stubif(!jt.isSelectionEmpty()){TreePath[] selectionpath=jt.getSelectionPaths();  //获得所有被选中的节点for(int i=0;i<selectionpath.length;i++){TreePath treepath=selectionpath[i];  //object 数组的形式返回数组Object[] path=treepath.getPath();for(int j=0;j<path.length;j++){DefaultMutableTreeNode node=(DefaultMutableTreeNode)path[i];String s=node.getUserObject()+(j==(path.length-1)?"":"-->");System.out.println(s);}System.out.println();}}}});}public static void main(String[] args) {// TODO Auto-generated method stubnew TreeSelection();}}