java something

在实际开发过程中会经常使用JTree组件，平时会遇到这样或那样的问题，在此将偶得一点经验写下来，与大家共享，希望对大家有所帮助。

private JTree jtNetDevice;//数组件申明
private JScrollPane jspTree;//滚动面板申明

1、初始化
    DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("root");
    jtNetDevice = new JTree(rootNode);
    jtNetDevice.setAutoscrolls(true);
    getTreeSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);//设置单选模式
    jspTree = new JScrollPane();
    jspTree.getViewport().add(jtNetDevice, null);

2、三个经常使用的取值函数
  private DefaultTreeModel getTreeModel(){
    return (DefaultTreeModel)jtNetDevice.getModel();
  }

  private DefaultMutableTreeNode getRootNode(){
    return (DefaultMutableTreeNode)getTreeModel().getRoot();
  }
 
  private TreeSelectionModel getTreeSelectionModel(){
    return jtNetDevice.getSelectionModel();
  }
 

3、根据node得到path：
  TreePath visiblePath = new TreePath(getTreeModel().getPathToRoot(node));

4、根据Path展开到该节点
  jtNetDevice.makeVisible(visiblePath);

5、根据path设定该节点选定
  jtNetDevice.setSelectionPath(visiblePath);

6、选中节点的方法
  首先，根据节点得到树路径，其中chosen为需要选中的节点
  TreePath visiblePath = new TreePath( ( (DefaultTreeModel) jtNetDevice.getModel()).
                                        getPathToRoot(chosen));
  然后根据Path选中该节点
  jtNetDevice.setSelectionPath(visiblePath);

7、滚动到可见位置
  jtNetDevice.scrollPathToVisible(visiblePath);

8、给JTree添加右键弹出菜单
  void jtNetDevice_mouseReleased(MouseEvent e) {
    if (e.isPopupTrigger()) {
      jPopupMenu1.show(e.getComponent(), e.getX(), e.getY());//弹出右键菜单
    }
  }

9、关于JTree的展开
   // If expand is true, expands all nodes in the tree.
   // Otherwise, collapses all nodes in the tree.
   public void expandAll(JTree tree, boolean expand) {
       TreeNode root = (TreeNode)tree.getModel().getRoot();
  
       // Traverse tree from root
       expandAll(tree, new TreePath(root), expand);
   }
   private void expandAll(JTree tree, TreePath parent, boolean expand) {
       // Traverse children
       TreeNode node = (TreeNode)parent.getLastPathComponent();
       if (node.getChildCount() >= 0) {
           for (Enumeration e=node.children(); e.hasMoreElements(); ) {
               TreeNode n = (TreeNode)e.nextElement();
               TreePath path = parent.pathByAddingChild(n);
               expandAll(tree, path, expand);
           }
       }
  
       // Expansion or collapse must be done bottom-up
       if (expand) {
           tree.expandPath(parent);
       } else {
           tree.collapsePath(parent);
       }
   }
 

10、如何遍历JTree
   // 创建树
   JTree tree = new JTree();
  
   // 添加树节点......
  
   // 遍历所有节点
   visitAllNodes(tree);
  
   // 仅遍历展开的节点
   visitAllExpandedNodes(tree);
  
   // Traverse all nodes in tree
   public void visitAllNodes(JTree tree) {
       TreeNode root = (TreeNode)tree.getModel().getRoot();
       visitAllNodes(root);
   }
   public void visitAllNodes(TreeNode node) {
       // node is visited exactly once
       process(node);
  
       if (node.getChildCount() >= 0) {
           for (Enumeration e=node.children(); e.hasMoreElements(); ) {
               TreeNode n = (TreeNode)e.nextElement();
               visitAllNodes(n);
           }
       }
   }
  
   // Traverse all expanded nodes in tree
   public void visitAllExpandedNodes(JTree tree) {
       TreeNode root = (TreeNode)tree.getModel().getRoot();
       visitAllExpandedNodes(tree, new TreePath(root));
   }
   public void visitAllExpandedNodes(JTree tree, TreePath parent) {
       // Return if node is not expanded
       if (!tree.isVisible(parent)) {
           return;
       }
  
       // node is visible and is visited exactly once
       TreeNode node = (TreeNode)parent.getLastPathComponent();
       process(node);
  
       // Visit all children
       if (node.getChildCount() >= 0) {
           for (Enumeration e=node.children(); e.hasMoreElements(); ) {
               TreeNode n = (TreeNode)e.nextElement();
               TreePath path = parent.pathByAddingChild(n);
               visitAllExpandedNodes(tree, path);
           }
       }
   }