JTree

import  java.awt.Dimension;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.BoxLayout;
import javax.swing.tree.TreePath;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
/**//*
JTree的构造函数:
JTree()
JTree(Hashtable value)
JTree(Object[] value)//只有这个构造函数可以创建多个根结点
JTree(TreeModel newModel)
JTree(TreeNode root)
JTree(TreeNode root, boolean asksAllowsChildren)
JTree(Vector value)

*/
public class JTreeDemo
...{
public static void main (String[] args)
...{


   // 构造函数：JTree()
   JTree example1 = new JTree();



  
   // 构造函数：JTree(Object[] value)
   Object[] letters = ...{ " a " , " b " , " c " , " d " , " e " };
   JTree example2 = new JTree (letters);




   // 构造函数：JTree(TreeNode root)(TreeNode空)
   // 用空结点创建树
   DefaultMutableTreeNode node1 = new DefaultMutableTreeNode(); // 定义树结点
   JTree example3 = new JTree (node1); // 用此树结点做参数调用 JTree的构造函数创建含有一个根结点的树




   // 构造函数：JTree(TreeNode root)(同上,只是TreeNode非空)
   // 用一个根结点创建树
   DefaultMutableTreeNode node2 = new DefaultMutableTreeNode( " Color " );
   JTree example4 = new JTree (node2); // 结点不可以颜色,默认为白面黑字
   example4.setBackground (Color.lightGray);




   // 构造函数：JTree(TreeNode root, boolean asksAllowsChildren)(同上,只是TreeNode又有不同)
   // 使用DefaultMutableTreeNode类先用一个根结点创建树，设置为可添加孩子结点,再添加孩子结点
   DefaultMutableTreeNode color = new DefaultMutableTreeNode( " Color " , true );
   DefaultMutableTreeNode gray = new DefaultMutableTreeNode ( " Gray " );
   color.add (gray);
   color.add ( new DefaultMutableTreeNode ( " Red " ));
   gray.add ( new DefaultMutableTreeNode ( " Lightgray " ));
   gray.add ( new DefaultMutableTreeNode ( " Darkgray " ));
   color.add ( new DefaultMutableTreeNode ( " Green " ));
   JTree example5 = new JTree (color);
  
  
  
  
   // 构造函数：JTree(TreeNode root)(同上,只是TreeNode非空)
   // 通过逐个添加结点创建树
   DefaultMutableTreeNode biology = new DefaultMutableTreeNode ( " Biology " );
   DefaultMutableTreeNode animal = new DefaultMutableTreeNode ( " Animal " );
   DefaultMutableTreeNode mammal = new DefaultMutableTreeNode ( " Mammal " );
   DefaultMutableTreeNode horse = new DefaultMutableTreeNode ( " Horse " );
   mammal.add (horse);
   animal.add (mammal);
   biology.add (animal);
   JTree example6 = new JTree (biology);
   horse.isLeaf();
   horse.isRoot();
  
  


   // 构造函数:JTree(TreeModel newModel)
   // 用DefaultMutableTreeNodel类定义一个结点再用这个结点做参数定义一个用DefaultTreeMode
   // 创建一个树的模型,再用JTree的构造函数创建一个树
  
   DefaultMutableTreeNode root = new DefaultMutableTreeNode ( " Root1 " );
   DefaultMutableTreeNode child1 = new DefaultMutableTreeNode ( " Child1 " );
   DefaultMutableTreeNode child11 = new DefaultMutableTreeNode ( " Child11 " );
   DefaultMutableTreeNode child111 = new DefaultMutableTreeNode ( " Child111 " );
   root.add (child1); child1.add (child11); child11.add (child111);
  
  
  
   DefaultTreeModel model = new DefaultTreeModel (root);
  
   JTree example7 = new JTree (model);



   JPanel panel = new JPanel();
   panel.setLayout ( new BoxLayout (panel, BoxLayout.X_AXIS));
   panel.setPreferredSize ( new Dimension ( 700 , 400 ));
   panel.add ( new JScrollPane (example1)); // JTree必须放在JScrollPane上
   panel.add ( new JScrollPane (example2));
   panel.add ( new JScrollPane (example3));
   panel.add ( new JScrollPane (example4));
   panel.add ( new JScrollPane (example5));
   panel.add ( new JScrollPane (example6));
   panel.add ( new JScrollPane (example7));
  



   JFrame frame = new JFrame ( " JTreeDemo " );
   frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
   frame.setContentPane (panel);
   frame.pack();
   frame.show();
}
} ××××××××××××××××××××××××××××××××××××××××××××××

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);
           }
       }
   }