Java JTree树（Swing树组件）

树状结构是一种常用的信息表现形式，它可以直观地显示出一组信息的层次结构。Swing中的JTree类用来创建树，该类的常用构造方法如下表所示：

创建简单的树：

import javax.swing.*;
import javax.swing.tree.*;
import java.util.*;
import java.awt.*;

public class t2 extends JFrame {
	
	public t2() {
		setTitle("树操作");
		setBounds(400, 400, 400, 400);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		DefaultMutableTreeNode root = new DefaultMutableTreeNode("根节点");//创建根节点
		DefaultMutableTreeNode nodeFirst = new DefaultMutableTreeNode("一级子节点A");//创建一级节点
		root.add(nodeFirst);// 将一级节点添加到根节点
		DefaultMutableTreeNode nodeSecond = new DefaultMutableTreeNode("二级子节点", false);//创建不允许有子节点的二级节点
		
		nodeFirst.add(nodeSecond);//将二级节点添加到一级节点
		root.add(new DefaultMutableTreeNode("一级子节点B"));//创建一级节点
		
		JTree treeRoot = new JTree(root);// 利用根节点直接创建树
		add(treeRoot, BorderLayout.WEST);
		
		DefaultTreeModel treeModelDefault = new DefaultTreeModel(root);//利用根节点创建树模型，采用默认的判断方式
		JTree treeDefault = new JTree(treeModelDefault);//利用树模型创建树
		add(treeDefault, BorderLayout.CENTER);
		
		DefaultTreeModel treeModelPointed = new DefaultTreeModel(root,true);//利用根节点创建树模型，并采用非默认的判断方式
		
		JTree treePointed = new JTree(treeModelPointed);//利用树模型创建树
		add(treePointed, BorderLayout.EAST);
		
		setVisible(true);
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		t2 T = new t2();
	}

}

 树的节点选择操作

树的节点允许被选中和取消选中状态，通过捕获树节点的选择事件，可以处理相应的操作。树的选择模式有3种，通过TreeSelectionModel类的对象可以设置树的选择模式。可以通过JTree类的getSelectionModel()方法获得TreeSelectionModel类的对象，然后通过TreeSelectionModel类的setSelectionMode(int mode)方法设置选择模式。该方法的入口参数可以从下表中列出的该类的静态常量中选择。

import javax.swing.*;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.*;

import java.util.*;
import java.awt.*;

public class t2 extends JFrame {
	
	private static final int DISCONTIGUOUS_TREE_SELECTION = 4;//单选的常量值为1，连选的常量值为2，多选的常量值为4

	public t2() {
		setTitle("树操作");
		setBounds(400, 400, 400, 400);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		DefaultMutableTreeNode root = new DefaultMutableTreeNode("根节点");
		DefaultMutableTreeNode rootFirst = new DefaultMutableTreeNode("一级子节点");
		DefaultMutableTreeNode rootSecond = new DefaultMutableTreeNode("二级子节点",false);
		root.add(rootFirst);
		root.add(rootSecond);
		
		rootFirst.add(new DefaultMutableTreeNode("子节点A",true));
		
		DefaultTreeModel treeModel = new DefaultTreeModel(root);//采用树模型
		JTree tree = new JTree(treeModel);
		
		TreeSelectionModel treeSelect;
		treeSelect = tree.getSelectionModel();//获得树的选择模式
		treeSelect.setSelectionMode(DISCONTIGUOUS_TREE_SELECTION);//设置树的选择模式为多选
		tree.addTreeSelectionListener(new TreeSelectionListener() {
			
			@Override
			public void valueChanged(TreeSelectionEvent e) {
				// TODO Auto-generated method stub
				
				if(!tree.isSelectionEmpty()) {//判断节点是否被选中，被选中为0，没被选中为1
					TreePath[] selectionPath =tree.getSelectionPaths();//获取所有被选中节点的路径
					for(int i = 0; i < selectionPath.length; i++) {
						TreePath path = selectionPath[i];
						Object[] obj = path.getPath();//以Object数组的形式返回该路径中所有节点的对象
						for(int j = 0; j < obj.length; j++) {
							DefaultMutableTreeNode node = (DefaultMutableTreeNode) obj[j];// 获得节点
							System.out.print(node.getUserObject());
						}
						System.out.println();
					}
				}
				
			}
		});
		
		add(tree);
		setVisible(true);
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		t2 T = new t2();
	}

}

 

 树的定制

import javax.swing.*;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.*;

import java.util.*;
import java.awt.*;

public class t2 extends JFrame {
	
	private static final int DISCONTIGUOUS_TREE_SELECTION = 4;//单选的常量值为1，连选的常量值为2，多选的常量值为4

	public t2() {
		setTitle("树操作");
		setBounds(400, 400, 400, 400);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		DefaultMutableTreeNode root = new DefaultMutableTreeNode("企业人事管理系统");
		
		DefaultMutableTreeNode nodeFirstA = new DefaultMutableTreeNode("人事管理");
		nodeFirstA.add(new DefaultMutableTreeNode("账套管理"));
		nodeFirstA.add(new DefaultMutableTreeNode("考勤管理"));
		nodeFirstA.add(new DefaultMutableTreeNode("奖惩管理"));
		nodeFirstA.add(new DefaultMutableTreeNode("培训管理"));
		root.add(nodeFirstA);
		
		DefaultMutableTreeNode nodeFirstB = new DefaultMutableTreeNode("待遇管理");
		nodeFirstB.add(new DefaultMutableTreeNode("帐套管理"));
		nodeFirstB.add(new DefaultMutableTreeNode("人员设置"));
		nodeFirstB.add(new DefaultMutableTreeNode("待遇报表"));
		root.add(nodeFirstB);
		
		DefaultMutableTreeNode nodeFirstC = new DefaultMutableTreeNode("系统维护");
		nodeFirstC.add(new DefaultMutableTreeNode("企业架构"));
		nodeFirstC.add(new DefaultMutableTreeNode("基本资料"));
		nodeFirstC.add(new DefaultMutableTreeNode("系统初始化"));
		root.add(nodeFirstC);
		
		JTree tree = new JTree(root);
		tree.setRootVisible(false);//不显示树的根节点
		tree.setRowHeight(20);//树节点的行高为20像素
		tree.setFont(new Font("宋体", Font.BOLD, 14));//设置树结点的字体
		//节点间不采用连接线
		tree.putClientProperty("JTree.lineStyle", "None");
		DefaultTreeCellRenderer treeCellRenderer;// 获得树节点的绘制对象
		treeCellRenderer = (DefaultTreeCellRenderer) tree.getCellRenderer();
		treeCellRenderer.setLeafIcon(null);// 设置叶子节点不采用图标
		treeCellRenderer.setClosedIcon(null);// 设置节点折叠时不采用图标
		treeCellRenderer.setOpenIcon(null);// 设置节点展开时不采用图标
		Enumeration<?> enumeration; // 按前序遍历所有树节点
		enumeration = root.preorderEnumeration();
		
		while (enumeration.hasMoreElements()) {
			DefaultMutableTreeNode node;
			node = (DefaultMutableTreeNode) enumeration.nextElement();
			if (!node.isLeaf()) {// 判断是否为叶子节点
				// 创建该节点的路径
				TreePath path = new TreePath(node.getPath());
				tree.expandPath(path);// 如果不是则展开该节点
			}
		}
		add(tree);
		setVisible(true);
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		t2 T = new t2();
	}

}

维护树模型：

import java.util.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;
import javax.swing.tree.*;

public class t3 extends JFrame{
	
	private JPanel panel = new JPanel();
	private JScrollPane scrollPane = new JScrollPane();
	private JTextField textField = new JTextField();
	private JLabel label = new JLabel("名称:");
	private JButton addButton = new JButton("添加");
	private JButton upButton = new JButton("修改");
	private JButton delButton = new JButton("删除");
	
	private DefaultTreeModel treeModel;
	private JTree tree;
	
	public t3() {
		setTitle("树操作");
		setBounds(400, 400, 400, 400);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		add(scrollPane, BorderLayout.WEST);
		add(panel, BorderLayout.SOUTH);
		
		DefaultMutableTreeNode root = new DefaultMutableTreeNode("根节点");
		
		DefaultMutableTreeNode rootFirst = new DefaultMutableTreeNode("节点一");
		rootFirst.add(new DefaultMutableTreeNode("节点A", true));
		rootFirst.add(new DefaultMutableTreeNode("节点B", true));
		root.add(rootFirst);
		
		DefaultMutableTreeNode rootSecond = new DefaultMutableTreeNode("节点二");
		rootSecond.add(new DefaultMutableTreeNode("节点C", true));
		rootSecond.add(new DefaultMutableTreeNode("节点D", true));
		root.add(rootSecond);
		
		DefaultMutableTreeNode rootThird = new DefaultMutableTreeNode("节点三");
		rootThird.add(new DefaultMutableTreeNode("节点E", true));
		rootThird.add(new DefaultMutableTreeNode("节点F", true));
		root.add(rootThird);
		
		treeModel = new DefaultTreeModel(root);
		
		tree = new JTree(treeModel);
		
		scrollPane.setViewportView(tree);
		
		panel.add(label);
		textField = new JTextField();
		textField.setText("请输入……");
		textField.setColumns(10);
		panel.add(textField);
		
		addButton.addActionListener(new ActionListener() {
			
			@Override
			public void actionPerformed(ActionEvent e) {
				// TODO Auto-generated method stub
				DefaultMutableTreeNode node = new DefaultMutableTreeNode(textField.getText());//创建想要添加的节点
				TreePath selectionPath = tree.getSelectionPath();//获得选中的父节点路径
				DefaultMutableTreeNode parentNode = (DefaultMutableTreeNode) selectionPath.getLastPathComponent();//获得选中的父节点
				treeModel.insertNodeInto(node, parentNode, parentNode.getChildCount());//插入节点到所有子节点之后
				TreePath path = selectionPath.pathByAddingChild(node);// 获得新添加节点的路径
				if (!tree.isVisible(path)) {
					tree.makeVisible(path);
				}
			}
		});
		panel.add(addButton);
		
		upButton.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				// 获得选中的欲修改节点的路径
				TreePath selectionPath = tree.getSelectionPath();
				DefaultMutableTreeNode node = (DefaultMutableTreeNode) selectionPath.getLastPathComponent();// 获得选中的欲修改节点
				node.setUserObject(textField.getText());// 修改节点的用户标签
				treeModel.nodeChanged(node);// 通知树模型该节点已经被修改
				tree.setSelectionPath(selectionPath);// 选中被修改的节点
			}
		});
		panel.add(upButton);
		
		delButton.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				DefaultMutableTreeNode node = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();// 获得选中的欲删除节点
				// 查看欲删除的节点是否为根节点，根节点不允许删除
				if (!node.isRoot()) {
					DefaultMutableTreeNode nextSelectedNode = node.getNextSibling();// 获得下一个兄弟节点，以备选中
					if (nextSelectedNode == null)// 查看是否存在兄弟节点
						nextSelectedNode = (DefaultMutableTreeNode) node.getParent();// 如果不存在则选中其父节点
					treeModel.removeNodeFromParent(node);// 删除节点
					tree.setSelectionPath(new TreePath(nextSelectedNode.getPath()));// 选中节点
				}
			}
		});
		panel.add(delButton);
		
		setVisible(true);
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		t3 test = new t3();

	}

}

 处理展开节点事件：

import java.awt.*;

import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;

public class ExampleFrame_06 extends JFrame {
	
	private static final long serialVersionUID = 1L;
	private JTree tree;
	
	public static void main(String args[]) {
		ExampleFrame_06 frame = new ExampleFrame_06();
		frame.setVisible(true);
	}
	
	public ExampleFrame_06() {
		super();
		setTitle("处理展开节点事件");
		setBounds(100, 100, 500, 375);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		DefaultMutableTreeNode root = new DefaultMutableTreeNode("倾诚爱家");
		
		DefaultMutableTreeNode nodeA = new DefaultMutableTreeNode("经理办公室");
		root.add(nodeA);
		
		DefaultMutableTreeNode nodeB = new DefaultMutableTreeNode("人事部");
		root.add(nodeB);
		
		DefaultMutableTreeNode nodeC = new DefaultMutableTreeNode("技术部");
		root.add(nodeC);
		nodeC.add(new DefaultMutableTreeNode("网络维护部"));
		nodeC.add(new DefaultMutableTreeNode("应用开发部"));
		
		DefaultMutableTreeNode nodeD = new DefaultMutableTreeNode("服务部");
		root.add(nodeD);
		nodeD.add(new DefaultMutableTreeNode("网络服务部"));
		nodeD.add(new DefaultMutableTreeNode("内勤开发部"));
		
		DefaultMutableTreeNode nodeE = new DefaultMutableTreeNode("推广部");
		root.add(nodeE);
		
		tree = new JTree(root);
// 捕获树节点将要被展开或折叠的事件
tree.addTreeWillExpandListener(new TreeWillExpandListener() {
	// 树节点将要被折叠时触发
	public void treeWillCollapse(TreeExpansionEvent e) {
		TreePath path = e.getPath();// 获得将要被折叠节点的路径
		DefaultMutableTreeNode node = (DefaultMutableTreeNode) path
				.getLastPathComponent();// 获得将要被折叠的节点
		System.out.println("节点“" + node + "”将要被折叠！");
	}
	
	// 树节点将要被展开时触发
	public void treeWillExpand(TreeExpansionEvent e) {
		TreePath path = e.getPath();// 获得将要被展开节点的路径
		DefaultMutableTreeNode node = (DefaultMutableTreeNode) path
				.getLastPathComponent();// 获得将要被展开的节点
		System.out.println("节点“" + node + "”将要被展开！");
	}
});
// 捕获树节点已经被展开或折叠的事件
tree.addTreeExpansionListener(new TreeExpansionListener() {
	// 树节点已经折叠时触发
	public void treeCollapsed(TreeExpansionEvent e) {
		TreePath path = e.getPath();// 获得已经被折叠节点的路径
		DefaultMutableTreeNode node = (DefaultMutableTreeNode) path
				.getLastPathComponent();// 获得已经被折叠的节点
		System.out.println("节点“" + node + "”已经被折叠！");
		System.out.println();
	}
	
	// 树节点已经被展开时触发
	public void treeExpanded(TreeExpansionEvent e) {
		TreePath path = e.getPath();// 获得已经被展开节点的路径
		DefaultMutableTreeNode node = (DefaultMutableTreeNode) path
				.getLastPathComponent();// 获得已经被展开的节点
		System.out.println("节点“" + node + "”已经被展开！");
		System.out.println();
	}
});
		getContentPane().add(tree, BorderLayout.CENTER);
		
	}
	
}