树(Tree)的使用与介绍
使用JTree组件：
java.lang.Object
--java.awt.Component
--java.awt.Container
--javax.swing.JComponent
--javax.swing.JTree
JTree构造函数:
JTree():建立一棵系统默认的树。
JTree(Hashtable value):利用Hashtable建立树，不显示root node(根节点).
JTree(Object[] value):利用Object Array建立树，不显示root node.
JTree(TreeModel newModel):利用TreeModel建立树。
JTree(TreeNode root):利用TreeNode建立树。
JTree(TreeNode root,boolean asksAllowsChildren):利用TreeNode建立树，并决定是否允许子节点的存在.
JTree(Vector value):利用Vector建立树，不显示root node.
范例:
InitalTree.java
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class InitalTree{
public InitalTree(){
JFrame f=new JFrame("TreeDemo");
Container contentPane=f.getContentPane();
JTree tree=new JTree();
JScrollPane scrollPane=new JScrollPane();
scrollPane.setViewportView(tree);
contentPane.add(scrollPane);
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
}
public static void main(String[] args){
new InitalTree();
}
}
10-2:以Hashtable构造JTree:
上面的例子对我们并没有裨的帮助，因为各个节点的数据均是java的默认值，而非我们自己设置的。因此我们需利用其他JTree
构造函数来输入我们想要的节点数据。以下范例我们以Hashtable当作JTree的数据输入:
范例：TreeDemo1.java
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
public class TreeDemo1{
public TreeDemo1(){
JFrame f=new JFrame("TreeDemo1");
Container contentPane=f.getContentPane();
String[] s1={"公司文件","个人信件","私人文件"};
String[] s2={"本机磁盘(C:)","本机磁盘(D:)","本机磁盘(E:)"};
String[] s3={"奇摩站","职棒消息","网络书店"};
Hashtable hashtable1=new Hashtable();
Hashtable hashtable2=new Hashtable();
hashtable1.put("我的公文包",s1);
hashtable1.put("我的电脑",s2);
hashtable1.put("收藏夹",hashtable2);
hashtable2.put("网站列表",s3);
Font font = new Font("Dialog", Font.PLAIN, 12);
Enumeration keys = UIManager.getLookAndFeelDefaults().keys();
/**定义widnows界面**/
while (keys.hasMoreElements()) {
Object key = keys.nextElement();
if (UIManager.get(key) instanceof Font) {
UIManager.put(key, font);
}
}
try{
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
}catch(Exception el){
System.exit(0);
}
/**定义widnows界面**/
JTree tree=new JTree(hashtable1);
JScrollPane scrollPane=new JScrollPane();
scrollPane.setViewportView(tree);
contentPane.add(scrollPane);
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
}
public static void main(String[] args){
new TreeDemo1();
}
}
纯XP界面的设置：
10-3:以TreeNode构造JTree:
JTree上的每一个节点就代表一个TreeNode对象，TreeNode本身是一个Interface,里面定义了7个有关节点的方法，例如判断是否
为树叶节点、有几个子节点(getChildCount())、父节点为何(getparent())等等、这些方法的定义你可以在javax.swing.tree的
package中找到，读者可自行查阅java api文件。在实际的应用上，一般我们不会直接实作此界面，而是采用java所提供的
DefaultMutableTreeMode类，此类是实作MutableTreeNode界面而来，并提供了其他许多实用的方法。MutableTreeNode本身也是一
个Interface,且继承了TreeNode界面此类主要是定义一些节点的处理方式，例如新增节点(insert())、删除节点(remove())、设置
节点(setUserObject())等。整个关系如下图:
TreeNode----extends--->MutableTreeNode---implements---DefaultMutableTreeNode
接下来我们来看如何利DefaultMutableTreeNode来建立JTree,我们先来看DefaultMutableTreeNode的构造函数:
DefaultMutableTreeNode构造函数:
DefaultMutableTreeNode():建立空的DefaultMutableTreeNode对象。
DefaultMutableTreeNode(Object userObject):建立DefaultMutableTreeNode对象，节点为userObject对象。
DefaultMutableTreeNode(Object userObject,Boolean allowsChildren):建立DefaultMutableTreeNode对象，节点为userObject对
象并决定此节点是否允许具有子节点。
以下为利用DefaultMutableTreeNode建立JTree的范例:TreeDemo2.java
此程序"资源管理器"为此棵树的根节点.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
public class TreeDemo2{
public TreeDemo2(){
JFrame f=new JFrame("TreeDemo2");
Container contentPane=f.getContentPane();
DefaultMutableTreeNode root=new DefaultMutableTreeNode("资源管理器");
DefaultMutableTreeNode node1=new DefaultMutableTreeNode("我的公文包");
DefaultMutableTreeNode node2=new DefaultMutableTreeNode("我的电脑");
DefaultMutableTreeNode node3=new DefaultMutableTreeNode("收藏夹");
DefaultMutableTreeNode node4=new DefaultMutableTreeNode("Readme");
root.add(node1);
root.add(node2);
root.add(node3);
root.add(node4);
DefaultMutableTreeNode leafnode=new DefaultMutableTreeNode("公司文件");
node1.add(leafnode);
leafnode=new DefaultMutableTreeNode("私人文件");
node1.add(leafnode);
leafnode=new DefaultMutableTreeNode("个人信件");
leafnode=new DefaultMutableTreeNode("本机磁盘(C:)");
node2.add(leafnode);
leafnode=new DefaultMutableTreeNode("本机磁盘(D:)");
node2.add(leafnode);
leafnode=new DefaultMutableTreeNode("本机磁盘(E:)");
node2.add(leafnode);
DefaultMutableTreeNode node31=new DefaultMutableTreeNode("网站列表");
node3.add(node31);
leafnode=new DefaultMutableTreeNode("奇摩站");
node31.add(leafnode);
leafnode=new DefaultMutableTreeNode("职棒消息");
node31.add(leafnode);
leafnode=new DefaultMutableTreeNode("网络书店");
node31.add(leafnode);
JTree tree=new JTree(root);
JScrollPane scrollPane=new JScrollPane();
scrollPane.setViewportView(tree);
contentPane.add(scrollPane);
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
}
public static void main(String[] args){
new TreeDemo2();
}
}
10-4:以TreeModel构造JTree.
除了以节点的观念(TreeNode)建立树之外，你可以用data model的模式建立树。树的data model称为TreeModel,用此模式的好处
是可以触发相关的树事件，来处理树可能产生的一些变动。TreeModel是一个interface,里面定义了8种方法;如果你是一个喜欢自己
动手做的人，或是你想显示的数据格式很复杂，你可以考虑直接实作TreeModel界面中所定义的方法来构造出JTree.TreeModel界面
的方法如下所示:
TreeModel方法:
void addTreeModelListener(TreeModelListener l):增加一个TreeModelListener来监控TreeModelEvent事件。
Object getChild(Object parent,int index):返回子节点。
int getChildCount(Object parent):返回子节点数量.
int getIndexOfChild(Object parent,Object child):返回子节点的索引值。
Object getRoot():返回根节点。
boolean isLeaf(Object node):判断是否为树叶节点。
void removeTreeModelListener(TreeModelListener l):删除TreeModelListener。
void valueForPathChanged(TreePath path,Object newValue):当用户改变Tree上的值时如何应对。
你可以实作出这8种方法，然后构造出自己想要的JTree,不过在大部份的情况下我们通常不会这样做，毕竟要实作出这8种方法不
是件很轻松的事，而且java本身也提供了一个默认模式，叫做DefaultTreeModel,这个类已经实作了TreeModel界面，也另外提供许
多实用的方法。利用这个默认模式，我们便能很方便的构造出JTree出来了。下面为DefaultTreeModel的构造函数与范例:
DefaultTreeModel构造函数:
DefaultTreeModel(TreeNode root):建立DefaultTreeModel对象，并定出根节点。
DefaultTreeModel(TreeNode root,Boolean asksAllowsChildren):建立具有根节点的DefaultTreeModel对象，并决定此节点是否允
许具有子节点。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
import com.incors.plaf.alloy.*;//组件的下载网址http://www.incors.com/lookandfeel/
/*将alloy.jar放在c:\j2sdk1.4.0\jre\lib\ext\目录下.
*/
public class TreeDemo3
{
public TreeDemo3()
{
JFrame f = new JFrame("TreeDemo");
Container contentPane = f.getContentPane();
DefaultMutableTreeNode root = new DefaultMutableTreeNode("资源管理器");
DefaultMutableTreeNode node1 = new DefaultMutableTreeNode("我的公文包");
DefaultMutableTreeNode node2 = new DefaultMutableTreeNode("我的电脑");
DefaultMutableTreeNode node3 = new DefaultMutableTreeNode("收藏夹");
DefaultMutableTreeNode node4 = new DefaultMutableTreeNode("Readme");
DefaultTreeModel treeModel = new DefaultTreeModel(root);
/*DefaultTreeModel类所提供的insertNodeInto()方法加入节点到父节点的数量.
*利用DefaultMutableTreeNode类所提供的getChildCount()方法取得目前子节点的数量.
*/
treeModel.insertNodeInto(node1, root, root.getChildCount());
treeModel.insertNodeInto(node2, root, root.getChildCount());
treeModel.insertNodeInto(node3, root, root.getChildCount());
treeModel.insertNodeInto(node4, root, root.getChildCount());
DefaultMutableTreeNode leafnode = new
DefaultMutableTreeNode("公司文件");
//DefaultTreeModel类所提供的insertNodeInto()方法加入节点到父节点的数量.
treeModel.insertNodeInto(leafnode, node1, node1.getChildCount());
leafnode = new DefaultMutableTreeNode("个人信件");
treeModel.insertNodeInto(leafnode, node1, node1.getChildCount());
leafnode = new DefaultMutableTreeNode("私人文件");
treeModel.insertNodeInto(leafnode, node1, node1.getChildCount());
leafnode = new DefaultMutableTreeNode("本机磁盘(C:)");
treeModel.insertNodeInto(leafnode, node2, node2.getChildCount());
leafnode = new DefaultMutableTreeNode("本机磁盘(D:)");
treeModel.insertNodeInto(leafnode, node2, node2.getChildCount());
leafnode = new DefaultMutableTreeNode("本机磁盘(E:)");
treeModel.insertNodeInto(leafnode, node2, node2.getChildCount());
DefaultMutableTreeNode node31 = new DefaultMutableTreeNode("网站列表");
treeModel.insertNodeInto(node31, node3, node3.getChildCount());
leafnode = new DefaultMutableTreeNode("奇摩站");
treeModel.insertNodeInto(leafnode, node3, node3.getChildCount());
leafnode = new DefaultMutableTreeNode("职棒消息");
treeModel.insertNodeInto(leafnode, node3, node3.getChildCount());
leafnode = new DefaultMutableTreeNode("网络书店");
treeModel.insertNodeInto(leafnode, node3, node3.getChildCount());
try {
LookAndFeel alloyLnF = new AlloyLookAndFeel();
UIManager.setLookAndFeel(alloyLnF);
} catch (UnsupportedLookAndFeelException ex) {
// You may handle the exception here
}
// this line needs to be implemented in order to make JWS work properly
UIManager.getLookAndFeelDefaults().put("ClassLoader", getClass().getClassLoader());
//以TreeModel建立JTree。
JTree tree = new JTree(treeModel);
/*改变JTree的外观**/
tree.putClientProperty("JTree.lineStyle","Horizontal");
/*改变JTree的外观**/
JScrollPane scrollPane = new JScrollPane();
scrollPane.setViewportView(tree);
contentPane.add(scrollPane);
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
public static void main(String args[]) {
new TreeDemo3();
}
}
10-5:改变JTree的外观:
你可以使用JComponent所提供的putClientProperty(Object key,Object value)方法来设置java默认的JTree外观，设置方式共有
3种:
1.tree.putClientProperty("JTree.lineStyle","None"):java默认值。
2.tree.putClientProperty("JTree.lineStyle","Horizontal"):使JTree的文件夹间具有水平分隔线。
3.tree.putClientProperty("JTree.lineStyle","Angled"):使JTree具有类似Windows文件管理器的直角连接线。
具体怎样做，可看上例.
10-6:更换JTree节点图案:
JTree利用TreeCellRenderer界面来运行绘制节点的工作，同样的，你不需要直接支实作这个界面所定义的方法，因为java本身提
供一个已经实作好的类来给我们使用，此类就是DefaultTreeCellRenderer,你可以在javax.swing.tree package中找到此类所提供
的方法。下面为使用DefaultTreeCellRenderer更改节点图案的一个例子:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
import com.incors.plaf.alloy.*;
public class TreeDemo4{
public TreeDemo4(){
JFrame f=new JFrame("TreeDemo");
Container contentPane=f.getContentPane();
DefaultMutableTreeNode root = new DefaultMutableTreeNode("资源管理器");
DefaultMutableTreeNode node1 = new DefaultMutableTreeNode("我的公文包");
DefaultMutableTreeNode node2 = new DefaultMutableTreeNode("我的电脑");
DefaultMutableTreeNode node3 = new DefaultMutableTreeNode("收藏夹");
DefaultMutableTreeNode node4 = new DefaultMutableTreeNode("Readme");
DefaultTreeModel treeModel = new DefaultTreeModel(root);
treeModel.insertNodeInto(node1, root, root.getChildCount());
treeModel.insertNodeInto(node2, root, root.getChildCount());
treeModel.insertNodeInto(node3, root, root.getChildCount());
treeModel.insertNodeInto(node4, root, root.getChildCount());
DefaultMutableTreeNode leafnode = new
DefaultMutableTreeNode("公司文件");
treeModel.insertNodeInto(leafnode, node1, node1.getChildCount());
leafnode = new DefaultMutableTreeNode("个人信件");
treeModel.insertNodeInto(leafnode, node1, node1.getChildCount());
leafnode = new DefaultMutableTreeNode("私人文件");
treeModel.insertNodeInto(leafnode, node1, node1.getChildCount());
leafnode = new DefaultMutableTreeNode("本机磁盘(C:)");
treeModel.insertNodeInto(leafnode, node2, node2.getChildCount());
leafnode = new DefaultMutableTreeNode("本机磁盘(D:)");
treeModel.insertNodeInto(leafnode, node2, node2.getChildCount());
leafnode = new DefaultMutableTreeNode("本机磁盘(E:)");
treeModel.insertNodeInto(leafnode, node2, node2.getChildCount());
DefaultMutableTreeNode node31 = new DefaultMutableTreeNode("网站列表");
treeModel.insertNodeInto(node31, node3, node3.getChildCount());
leafnode = new DefaultMutableTreeNode("奇摩站");
treeModel.insertNodeInto(leafnode, node3, node3.getChildCount());
leafnode = new DefaultMutableTreeNode("职棒消息");
treeModel.insertNodeInto(leafnode, node3, node3.getChildCount());
leafnode = new DefaultMutableTreeNode("网络书店");
treeModel.insertNodeInto(leafnode, node3, node3.getChildCount());
try {
LookAndFeel alloyLnF = new AlloyLookAndFeel();
UIManager.setLookAndFeel(alloyLnF);
} catch (UnsupportedLookAndFeelException ex) {
// You may handle the exception here
}
// this line needs to be implemented in order to make JWS work properly
UIManager.getLookAndFeelDefaults().put("ClassLoader", getClass().getClassLoader());
JTree tree = new JTree(treeModel);
tree.setRowHeight(20);
DefaultTreeCellRenderer cellRenderer=(DefaultTreeCellRenderer)tree.getCellRenderer();
cellRenderer.setLeafIcon(new ImageIcon("..\\icons\\leaf.gif"));
cellRenderer.setOpenIcon(new ImageIcon("..\\icons\\open.gif"));
cellRenderer.setClosedIcon(new ImageIcon("..\\icons\\close.gif"));
cellRenderer.setFont(new Font("宋体",Font.PLAIN,12));//设置字体.
cellRenderer.setBackgroundNonSelectionColor(Color.white);
cellRenderer.setBackgroundSelectionColor(Color.yellow);
cellRenderer.setBorderSelectionColor(Color.red);
/*设置选时或不选时，文字的变化颜色
*/
cellRenderer.setTextNonSelectionColor(Color.black);
cellRenderer.setTextSelectionColor(Color.blue);
JScrollPane scrollPane=new JScrollPane();
scrollPane.setViewportView(tree);
contentPane.add(scrollPane);
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
public static void main(String args[]) {
new TreeDemo4();
}
}
Window Xp界面:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
import com.incors.plaf.alloy.*;
public class TreeDemo3
{
public TreeDemo3()
{
//设置成Alloy界面样式
try {
AlloyLookAndFeel.setProperty("alloy.isLookAndFeelFrameDecoration", "true");
LookAndFeel alloyLnF = new AlloyLookAndFeel();
JFrame.setDefaultLookAndFeelDecorated(true);
UIManager.setLookAndFeel(alloyLnF);
} catch (UnsupportedLookAndFeelException ex) {
// You may handle the exception here
}
// this line needs to be implemented in order to make JWS work properly
UIManager.getLookAndFeelDefaults().put("ClassLoader", getClass().getClassLoader());
//JDialog.setDefaultLookAndFeelDecorated(true);
JFrame f = new JFrame("firstTree");
Container contentPane = f.getContentPane();
// if (contentPane instanceof JComponent) {
// ((JComponent) contentPane).setMinimumSize(new Dimension(100, 100));
//}
// Container contentPane = f.getContentPane();
DefaultMutableTreeNode root = new DefaultMutableTreeNode("资源管理器");
DefaultMutableTreeNode node1 = new DefaultMutableTreeNode("我的公文包");
DefaultMutableTreeNode node2 = new DefaultMutableTreeNode("我的电脑");
DefaultMutableTreeNode node3 = new DefaultMutableTreeNode("收藏夹");
DefaultMutableTreeNode node4 = new DefaultMutableTreeNode("Readme");
DefaultTreeModel treeModel = new DefaultTreeModel(root);
treeModel.insertNodeInto(node1, root, root.getChildCount());
treeModel.insertNodeInto(node2, root, root.getChildCount());
treeModel.insertNodeInto(node3, root, root.getChildCount());
treeModel.insertNodeInto(node4, root, root.getChildCount());
DefaultMutableTreeNode leafnode = new
DefaultMutableTreeNode("公司文件");
treeModel.insertNodeInto(leafnode, node1, node1.getChildCount());
leafnode = new DefaultMutableTreeNode("个人信件");
treeModel.insertNodeInto(leafnode, node1, node1.getChildCount());
leafnode = new DefaultMutableTreeNode("私人文件");
treeModel.insertNodeInto(leafnode, node1, node1.getChildCount());
leafnode = new DefaultMutableTreeNode("本机磁盘(C:)");
treeModel.insertNodeInto(leafnode, node2, node2.getChildCount());
leafnode = new DefaultMutableTreeNode("本机磁盘(D:)");
treeModel.insertNodeInto(leafnode, node2, node2.getChildCount());
leafnode = new DefaultMutableTreeNode("本机磁盘(E:)");
treeModel.insertNodeInto(leafnode, node2, node2.getChildCount());
DefaultMutableTreeNode node31 = new DefaultMutableTreeNode("网站列表");
treeModel.insertNodeInto(node31, node3, node3.getChildCount());
leafnode = new DefaultMutableTreeNode("奇摩站");
treeModel.insertNodeInto(leafnode, node3, node3.getChildCount());
leafnode = new DefaultMutableTreeNode("职棒消息");
treeModel.insertNodeInto(leafnode, node3, node3.getChildCount());
leafnode = new DefaultMutableTreeNode("网络书店");
treeModel.insertNodeInto(leafnode, node3, node3.getChildCount());
JTree tree = new JTree(treeModel);
/*改变JTree的外观**/
// tree.putClientProperty("JTree.lineStyle","Horizontal");
/*改变JTree的外观**/
JScrollPane scrollPane = new JScrollPane();
scrollPane.setViewportView(tree);
contentPane.add(scrollPane);
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
public static void main(String args[]) {
new TreeDemo3();
}
}
10-7:JTree的事件处理模式:
在此节中，我们将详细介绍JTree两个常用的事件与处理，分别是TreeModeEvent与TreeSelectionEvent.
10-7-1:处理TreeModeEvent事件：
当树的结构上有任何改变时，例如节点值改变了、新增节点、删除节点等，都会TreeModelEvent事件，要处理这样的事件必须实
作TreeModelListener界面，此界面定义了4个方法，如下所示:
TreeModelListener方法:
Void treeNodesChanged(TreeModelEvent e):当节点改变时系统就会云调用这个方法。
Void treeNodesInserted(TreeModelEvent e):当新增节时系统就会去调用这个方法。
Void treeNodesRemoved(TreeModeEvent e):当删除节点时系统就会去调用这个方法。
Void treeStructureChanged(TreeModelEvent e):当树结构改变时系统就会去调用这个方法。
TreeModelEvent类本身提供了5个方法，帮我们取得事件的信息，如下所示:
TreeModelEvent方法：
int[] getChildIndices():返回子节点群的索引值。
Object[] getChildren():返回子节点群.
Object[] getPath():返回Tree中一条path上(从root nod到leaf node)的节点。
TreePath getTreePath():取得目前位置的Tree Path.
String toString()：取得蝗字符串表示法.
由TreeModelEvent的getTreePath()方法就可以得到TreePath对象，此对象就能够让我们知道用户目前正选哪一个节点，
TreePath类最常用的方法为：
public Object getLastPathComponent():取得最深（内）层的节点。
public int getPathCount():取得此path上共有几个节点.
我们来看下面这个例子，用户可以在Tree上编辑节点，按下[Enter]键后就可以改变原有的值，并将改变的值显示在下面的
JLabel中:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;
import com.incors.plaf.alloy.*;
import com.incors.plaf.alloy.themes.bedouin.*;
public class TreeDemo5 implements TreeModelListener
{
JLabel label = null;
String nodeName = null; //原有节点名称
public TreeDemo5()
{
try {
AlloyLookAndFeel.setProperty("alloy.isLookAndFeelFrameDecoration", "true");
AlloyTheme theme = new BedouinTheme();//设置界面的外观，手册中共有5种样式
LookAndFeel alloyLnF = new AlloyLookAndFeel(theme);
UIManager.setLookAndFeel(alloyLnF);
} catch (UnsupportedLookAndFeelException ex) {
// You may handle the exception here
}
// this line needs to be implemented in order to make JWS work properly
UIManager.getLookAndFeelDefaults().put("ClassLoader", getClass().getClassLoader());
JFrame f = new JFrame("TreeDemo");
Container contentPane = f.getContentPane();
DefaultMutableTreeNode root = new DefaultMutableTreeNode("资源管理器");
DefaultMutableTreeNode node1 = new DefaultMutableTreeNode("文件夹");
DefaultMutableTreeNode node2 = new DefaultMutableTreeNode("我的电脑");
DefaultMutableTreeNode node3 = new DefaultMutableTreeNode("收藏夹");
DefaultMutableTreeNode node4 = new DefaultMutableTreeNode("Readme");
root.add(node1);
root.add(node2);
root.add(node3);
root.add(node4);
DefaultMutableTreeNode leafnode = new DefaultMutableTreeNode("公司文件");
node1.add(leafnode);
leafnode = new DefaultMutableTreeNode("个人信件");
node1.add(leafnode);
leafnode = new DefaultMutableTreeNode("私人文件");
node1.add(leafnode);
leafnode = new DefaultMutableTreeNode("本机磁盘(C:)");
node2.add(leafnode);
leafnode = new DefaultMutableTreeNode("本机磁盘(D:)");
node2.add(leafnode);
leafnode = new DefaultMutableTreeNode("本机磁盘(E:)");
node2.add(leafnode);
DefaultMutableTreeNode node31 = new DefaultMutableTreeNode("网站列表");
node3.add(node31);
leafnode = new DefaultMutableTreeNode("天勤网站");
node31.add(leafnode);
leafnode = new DefaultMutableTreeNode("足球消息");
node31.add(leafnode);
leafnode = new DefaultMutableTreeNode("网络书店");
node31.add(leafnode);
JTree tree = new JTree(root);
tree.setEditable(true);//设置JTree为可编辑的
tree.addMouseListener(new MouseHandle());//使Tree加入检测Mouse事件，以便取得节点名称
//下面两行取得DefaultTreeModel,并检测是否有TreeModelEvent事件.
DefaultTreeModel treeModel = (DefaultTreeModel)tree.getModel();
treeModel.addTreeModelListener(this);
JScrollPane scrollPane = new JScrollPane();
scrollPane.setViewportView(tree);
label = new JLabel("更改数据为: ");
contentPane.add(scrollPane,BorderLayout.CENTER);
contentPane.add(label,BorderLayout.SOUTH);
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
/*本方法实作TreeModelListener接口，本接口共定义四个方法，分别是TreeNodesChanged()
*treeNodesInserted()、treeNodesRemoved()、treeNodesRemoved()、
*treeStructureChanged().在此范例中我们只针对更改节点值的部份，因此只实作
*treeNodesChanged()方法.
*/
public void treeNodesChanged(TreeModelEvent e) {
TreePath treePath = e.getTreePath();
System.out.println(treePath);
//下面这行由TreeModelEvent取得的DefaultMutableTreeNode为节点的父节点，而不是用户点选
//的节点，这点读者要特别注意。要取得真正的节点需要再加写下面6行代码.
DefaultMutableTreeNode node = (DefaultMutableTreeNode)treePath.getLastPathComponent();
try {
//getChildIndices()方法会返回目前修改节点的索引值。由于我们只修改一个节点，因此节点索引值就放在index[0]
//的位置，若点选的节点为root node,则getChildIndices()的返回值为null,程序下面的第二行就在处理点选root
//node产生的NullPointerException问题.
int[] index = e.getChildIndices();
//由DefaultMutableTreeNode类的getChildAt()方法取得修改的节点对象.
node = (DefaultMutableTreeNode)node.getChildAt(index[0]);
} catch (NullPointerException exc) {}
//由DefaultMutableTreeNode类getUserObject()方法取得节点的内容，或是写成node.toString()亦相同.
label.setText(nodeName+"更改数据为: "+(String)node.getUserObject());
}
public void treeNodesInserted(TreeModelEvent e) {
}
public void treeNodesRemoved(TreeModelEvent e) {
}
public void treeStructureChanged(TreeModelEvent e) {
}
public static void main(String args[]) {
new TreeDemo5();
}
//处理Mouse点选事件
class MouseHandle extends MouseAdapter
{
public void mousePressed(MouseEvent e)
{
try{
JTree tree = (JTree)e.getSource();
//JTree的getRowForLocation()方法会返回节点的列索引值。例如本例中，“本机磁盘(D:)”的列索引值为4,此索引值
//会随着其他数据夹的打开或收起而变支，但“资源管理器”的列索引值恒为0.
int rowLocation = tree.getRowForLocation(e.getX(), e.getY());
/*JTree的getPathForRow()方法会取得从root node到点选节点的一条path,此path为一条直线，如程序运行的图示
*若你点选“本机磁盘(E:)”,则Tree Path为"资源管理器"-->"我的电脑"-->"本机磁盘(E:)",因此利用TreePath
*的getLastPathComponent()方法就可以取得所点选的节点.
*/
TreePath treepath = tree.getPathForRow(rowLocation);
TreeNode treenode = (TreeNode) treepath.getLastPathComponent();
nodeName = treenode.toString();
}catch(NullPointerException ne){}
}
}
}
注:上面的程序MouseHandle中:
int rowLocation = tree.getRowForLocation(e.getX(), e.getY());
TreePath treepath = tree.getPathForRow(rowLocation);
与：
TreePath treepath=tree.getSelectionPath();
等价，可互换。
我们将“我的电脑”改成“网上领居”:
我们再来看一个TreeModelEvent的例子，下面这个例子我们可以让用户自行增加、删除与修改节点：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;
import com.incors.plaf.alloy.*;
import com.incors.plaf.alloy.themes.bedouin.*;
public class TreeDemo6 implements ActionListener,TreeModelListener{
JLabel label=null;
JTree tree=null;
DefaultTreeModel treeModel=null;
String nodeName=null;//原有节点名称
public TreeDemo6(){
try {
AlloyLookAndFeel.setProperty("alloy.isLookAndFeelFrameDecoration", "true");
AlloyTheme theme = new BedouinTheme();
LookAndFeel alloyLnF = new AlloyLookAndFeel(theme);
UIManager.setLookAndFeel(alloyLnF);
} catch (UnsupportedLookAndFeelException ex) {
// You may handle the exception here
}
// this line needs to be implemented in order to make JWS work properly
UIManager.getLookAndFeelDefaults().put("ClassLoader", getClass().getClassLoader());
JFrame f=new JFrame("TreeDemo6");
Container contentPane=f.getContentPane();
DefaultMutableTreeNode root=new DefaultMutableTreeNode("资源管理器");
tree=new JTree(root);
tree.setEditable(true);
tree.addMouseListener(new MouseHandle());
treeModel=(DefaultTreeModel)tree.getModel();
treeModel.addTreeModelListener(this);
JScrollPane scrollPane=new JScrollPane();
scrollPane.setViewportView(tree);
JPanel panel=new JPanel();
JButton b=new JButton("新增节点");
b.addActionListener(this);
panel.add(b);
b=new JButton("删除节点");
b.addActionListener(this);
panel.add(b);
b=new JButton("清除所有节点");
b.addActionListener(this);
panel.add(b);
label=new JLabel("Action");
contentPane.add(panel,BorderLayout.NORTH);
contentPane.add(scrollPane,BorderLayout.CENTER);
contentPane.add(label,BorderLayout.SOUTH);
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);
}
});
}
//本方法运行新增、删除、清除所有节点的程序代码.
public void actionPerformed(ActionEvent ae){
if (ae.getActionCommand().equals("新增节点")){
DefaultMutableTreeNode parentNode=null;
DefaultMutableTreeNode newNode=new DefaultMutableTreeNode("新节点");
newNode.setAllowsChildren(true);
TreePath parentPath=tree.getSelectionPath();
//取得新节点的父节点
parentNode=(DefaultMutableTreeNode)(parentPath.getLastPathComponent());
//由DefaultTreeModel的insertNodeInto（）方法增加新节点
treeModel.insertNodeInto(newNode,parentNode,parentNode.getChildCount());
//tree的scrollPathToVisible()方法在使Tree会自动展开文件夹以便显示所加入的新节点。若没加这行则加入的新节点
//会被 包在文件夹中，你必须自行展开文件夹才看得到。
tree.scrollPathToVisible(new TreePath(newNode.getPath()));
label.setText("新增节点成功");
}
if (ae.getActionCommand().equals("删除节点")){
TreePath treepath=tree.getSelectionPath();
if (treepath!=null){
//下面两行取得选取节点的父节点.
DefaultMutableTreeNode selectionNode=(DefaultMutableTreeNode)treepath.getLastPathComponent();
TreeNode parent=(TreeNode)selectionNode.getParent();
if (parent!=null) {
//由DefaultTreeModel的removeNodeFromParent()方法删除节点，包含它的子节点。
treeModel.removeNodeFromParent(selectionNode);
label.setText("删除节点成功");
}
}
}
if (ae.getActionCommand().equals("清除所有节点")){
//下面一行，由DefaultTreeModel的getRoot()方法取得根节点.
DefaultMutableTreeNode rootNode=(DefaultMutableTreeNode)treeModel.getRoot();
//下面一行删除所有子节点.
rootNode.removeAllChildren();
//删除完后务必运行DefaultTreeModel的reload()操作，整个Tree的节点才会真正被删除.
treeModel.reload();
label.setText("清除所有节点成功");
}
}
public void treeNodesChanged(TreeModelEvent e){
TreePath treePath=e.getTreePath();
DefaultMutableTreeNode node=(DefaultMutableTreeNode)treePath.getLastPathComponent();
try{
int[] index=e.getChildIndices();
node=(DefaultMutableTreeNode)node.getChildAt(index[0]);
}catch(NullPointerException exc){}
label.setText(nodeName+"更改数据为:"+(String)node.getUserObject());
}
public void treeNodesInserted(TreeModelEvent e){
System.out.println("new node insered");
}
public void treeNodesRemoved(TreeModelEvent e){
System.out.println("node deleted");
}
public void treeStructureChanged(TreeModelEvent e){
System.out.println("Structrue changed");
}
public static void main(String[] args){
new TreeDemo6();
}
class MouseHandle extends MouseAdapter{
public void mousePressed(MouseEvent e){
try{
JTree tree=(JTree)e.getSource();
int rowLocation=tree.getRowForLocation(e.getX(),e.getY());
TreePath treepath=tree.getPathForRow(rowLocation);
TreeNode treenode=(TreeNode)treepath.getLastPathComponent();
nodeName=treenode.toString();
}catch(NullPointerException ne){}
}
}
}
10-7-2：处理TreeSelectionEvent事件：
当我们在JTree上点选任何一个节点，都会触发TreeSelectionEvent事件，如果我们要处理这样的事件，必须实作
TreeSelectionListener界面，此界面只定义了一个方法，那就是valueChanged()方法。
TreeSelectionEvent最常用在处理显示节点的内容，例如你在文件图标中点两下就可以看到文件的内容。在JTree中选择节点
的方式共有3种，这3种情况跟选择JList上的项目是一模一样的，分别是：
DISCONTIGUOUS_TREE_SELECTION:可作单一选择，连续点选择（按住[Shift]键），不连续选择多个节点（按住[Ctrl]键）,
这是java默认值.
CONTINUOUS_TREE_SELECTION:按住[Shift]键，可对某一连续的节点区间作选取。
SINGLE_TREE_SELECTION:一次只能选一个节点。
你可以自行实作TreeSelectionModel制作作更复杂的选择方式，但通常是没有必要的，因为java提供了默认的选择模式类供我们
使用，那就是DefaultTreeSelectionModel,利用这个类我们可以很方便的设置上面3种选择模式。
下面这个范例，当用户点选了一个文件名时，就会将文件的内容显示出来。
TreeDemo7.java
import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import com.incors.plaf.alloy.*;
import com.incors.plaf.alloy.themes.glass.*;
public class TreeDemo7 implements TreeSelectionListener
{
JEditorPane editorPane;
public TreeDemo7()
{
JFrame f = new JFrame("TreeDemo");
Container contentPane = f.getContentPane();
DefaultMutableTreeNode root = new DefaultMutableTreeNode("资源管理器");
DefaultMutableTreeNode node = new DefaultMutableTreeNode("TreeDemo1.java");
root.add(node);
node = new DefaultMutableTreeNode("TreeDemo2.java");
root.add(node);
node = new DefaultMutableTreeNode("TreeDemo3.java");
root.add(node);
node = new DefaultMutableTreeNode("TreeDemo4.java");
root.add(node);
JTree tree = new JTree(root);
//设置Tree的选择模式为一次只能选择一个节点
tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
//检查是否有TreeSelectionEvent事件。
tree.addTreeSelectionListener(this);
//下面五行，JSplitPane中，左边是放含有JTree的JScrollPane,右边是放JEditorPane.
JScrollPane scrollPane1 = new JScrollPane(tree);
editorPane = new JEditorPane();
JScrollPane scrollPane2 = new JScrollPane(editorPane);
JSplitPane splitPane = new JSplitPane(
JSplitPane.HORIZONTAL_SPLIT,true, scrollPane1, scrollPane2);
contentPane.add(splitPane);
f.pack();
f.setVisible(true);
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
//本方法实作valueChanged()方法
public void valueChanged(TreeSelectionEvent e)
{
JTree tree = (JTree) e.getSource();
//利用JTree的getLastSelectedPathComponent()方法取得目前选取的节点.
DefaultMutableTreeNode selectionNode =
(DefaultMutableTreeNode)tree.getLastSelectedPathComponent();
String nodeName = selectionNode.toString();
//判断是否为树叶节点，若是则显示文件内容，若不是则不做任何事。
if (selectionNode.isLeaf())
{
/*取得文件的位置路径,System.getProperty("user.dir")可以取得目前工作的路径，
*System.getProperty("file.separator")是取得文件分隔符，例如在window环境的
*文件分陋符是"\",而Unix环境的文件分隔符刚好相反，是"/".利用System.getProperty()
*方法你可以取得下列的信息:
java.version 显示java版本
java.endor 显示java制造商
java.endor.url 显示java制造商URL
java.home 显示java的安装路径
java.class.version 显示java类版本
java.class.path 显示java classpath
os.name 显示操作系统名称
os.arch 显示操作系统结构，如x86
os.version 显示操作系统版本
file.separator 取得文件分隔符
path.separator 取得路径分隔符，如Unix是以“:”表示
line.separator 取得换行符号，如Unix是以"\n"表示
user.name 取得用户名称
user.home 取得用户家目录(home directory),如Windows中Administrator的家目
录为c:\Documents and Settings\Administrator
user.dir 取得用户目前的工作目录.
*/
String filepath = "file:"+System.getProperty("user.dir") +
System.getProperty("file.separator") +
nodeName;
try {
//利用JEditorPane的setPage()方法将文件内容显示在editorPane中。若文件路径错误，则会产生IOException.
editorPane.setPage(filepath);
} catch(IOException ex) {
System.out.println("找不到此文件");
}
}
}
public static void main(String[] args) {
SwingUtil.setLookAndFeel();
new TreeDemo7();
}
}
class SwingUtil{
public static final void setLookAndFeel() {
try{
Font font = new Font("JFrame", Font.PLAIN, 12);
Enumeration keys = UIManager.getLookAndFeelDefaults().keys();
while (keys.hasMoreElements()) {
Object key = keys.nextElement();
if (UIManager.get(key) instanceof Font) {
UIManager.put(key, font);
}
}
AlloyLookAndFeel.setProperty("alloy.isLookAndFeelFrameDecoration", "true");
AlloyTheme theme = new GlassTheme();
LookAndFeel alloyLnF = new AlloyLookAndFeel(theme);
JFrame.setDefaultLookAndFeelDecorated(true);
UIManager.setLookAndFeel(alloyLnF);
}catch(UnsupportedLookAndFeelException ex){
ex.printStackTrace();
}
}
}
10-8:JTree的其他操作:
我们在之前小节中曾说到Tree中的每一个节点都是一个TreeNode,并可利用JTree的setEditable()方法设置节点是否可编辑，
若要在Tree中找寻节点的父节点或子节点，或判断是否为树节点，皆可由实作TreeNode界面做到，但要编辑节点呢？java将编辑
节点的任务交给TreeCellEditor,TreeCellEditor本身是一个界面，里面只定义了getTreeCellEditor Component()方法，你可以实
作此方法使节点具有编辑的效果。不过你不用这么辛苦去实作这个方法，java本身提供了DefaultTreeCellEditor类来实作此方法
，亦提供了其他许多方法，例如取得节点内容(getCellEditorValue()) 、设置节点字体(setFont())、决定节点是否可编辑
(isCellEditable())等等。除非你觉得DefaultTreeCellEditor所提供的功能不够，你才需要去实作TreeCellEditor界面。你可以利
用JTree的getCellEditor()方法取得DefaultTreeCellEditor对象。当我们编辑节点时会触发ChangeEvent事件，你可以实作
CellEditorListener界面来处理此事件，CellEditorListener界面包括两个方法，分别是editingStopped(ChangeEvent e)与
editingCanceled(ChangeEvent e).若你没有实作TreeCellEditor界面，系统会以默认的DefaultTreeCellEdtior类来处理掉这两个
方法(你可以在DefaultTreeCellEditor中找到这两个方法)，因此你无须再编写任何的程序。
另外，JTree还有一种事件处理模式，那就是TreeExpansionEvent事件。要处理这个事件你必须实作TreeExpansionListener
界面，此界面定义了两个方法，分别是treeCollapsed(TreeExpansionEvent e)与treeExpanded(TreeExpansionEvent e).当节点展
开时系统就会自动调用treeExpanded()方法，当节点合起来时，系统就会自动调用treeCollapsed()方法。你可以在这两个方法中编
写所要处理事情的程序代码。处理事件的过程我们已在上面举过多次，这里就不再重复了，可参考下面的网站：
http://javaalmanac.com/egs/index.html