JTree 遍历叶节点
我用JTree做了一个QQ好友列表。当服务器发送一个在线好友的ID过来，如"100 500 200"，ID之间用空格分隔。我要如何遍历JTree，找到该叶节点，并设置setEnable(true)。求帮忙解决。字数有限，贴出关键代码：
public class QQClientMain extends JFrame {

  //登入者id
  private String owner;

  // 是否有消息
  private static boolean hasMessage;
   
 // 初始化中部(好友列表和群列表的显示)
  public void initCenter() {
  // 初始化好友列表
  DefaultMutableTreeNode root = new DefaultMutableTreeNode(new TreeNode("0","好友列表"));
  // 一级节点
  DefaultMutableTreeNode node1 = new DefaultMutableTreeNode(new TreeNode("1","我的好友"));
  DefaultMutableTreeNode node2 = new DefaultMutableTreeNode(new TreeNode("2","陌生人"));
  DefaultMutableTreeNode node3 = new DefaultMutableTreeNode(new TreeNode("3","黑名单"));
   
  // 子节点
  // 好友
  DefaultMutableTreeNode node1_1 = new DefaultMutableTreeNode(new TreeNode("100","张三","image/1-1.gif", "0"));
  DefaultMutableTreeNode node1_2 = new DefaultMutableTreeNode(new TreeNode("200","李四","image/2-1.gif", "0"));
  DefaultMutableTreeNode node1_3 = new DefaultMutableTreeNode(new TreeNode("300","王五","image/3-1.gif", "0"));
  DefaultMutableTreeNode node1_4 = new DefaultMutableTreeNode(new TreeNode("400","李流","image/4-1.gif", "0"));
  DefaultMutableTreeNode node1_5 = new DefaultMutableTreeNode(new TreeNode("500","黄山","image/5-1.gif", "0"));
  DefaultMutableTreeNode node1_6 = new DefaultMutableTreeNode(new TreeNode("600","武当","image/6-1.gif", "0"));
  // 陌生人
  DefaultMutableTreeNode node2_1 = new DefaultMutableTreeNode(new TreeNode("1300","张三1","image/4-1.gif", "0"));
  // 黑名单
  DefaultMutableTreeNode node3_1 = new DefaultMutableTreeNode(new TreeNode("1010","张三1","image/2-1.gif", "0"));
   
  jpt1_tree1 = new JTree(root);
  jpt1_tree1.setCellRenderer(new MyCellRenderer());
  jpt1_jsp1 = new JScrollPane(jpt1_tree1);
  // 设置单击展开树节点
  jpt1_tree1.setToggleClickCount(1);
   
  root.add(node1);
  root.add(node2);
  root.add(node3);
   
  node1.add(node1_1);
  node1.add(node1_2);
  node1.add(node1_3);
  node1.add(node1_4);
  node1.add(node1_5);
  node1.add(node1_6);



  node2.add(node2_1);
   
  node3.add(node3_1);

  //设置是否显示根节点的“展开/折叠”图标,默认是false  
  jpt1_tree1.setShowsRootHandles(false);  
  //设置节点是否可见,默认是true  
  jpt1_tree1.setRootVisible(false);
  jpt1_tree1.setEditable(false);
   
  //设置使用Windows风格外观  
  try {
  UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
  } catch (ClassNotFoundException e1) {
  e1.printStackTrace();
  } catch (InstantiationException e1) {
  e1.printStackTrace();
  } catch (IllegalAccessException e1) {
  e1.printStackTrace();
  } catch (UnsupportedLookAndFeelException e1) {
  e1.printStackTrace();
  }  
  //更新JTree的UI外观  
  SwingUtilities.updateComponentTreeUI(jpt1_tree1);  

   
  // 创建选项卡窗口
  jtp1 = new JTabbedPane(JTabbedPane.TOP);
  // 选项卡一:好友列表