treedemo6.java

详细介绍JTree两个常用的事件与处理,分别是TreeModeEvent与TreeSelectionEvent.

/*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.*;

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(){

// 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());
System.out.println("parentNode为:"+parentNode);

//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");
}
else {System.out.println("欲删节点为根节点！");}
}
else {System.out.println("未选中节点！");} 
}
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(); 

System.out.println(rootNode.getUserObject());
rootNode.setUserObject("");
//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){}
} 
}
}