如何利用JDOM,把JTree中所有节点写入到一个XML文件中？最好有现成的例子。谢谢了。

Question

关于XML和JTree的映射我在SUN的Java Web Services Tutorial里看到过一个例子不过是从XML-->JTree的反向应该不是很困难吧现成的例子倒是没有，呵呵

Answer 1

http://java.sun.com/webservices/docs/1.0/tutorial/doc/JAXPDOM6.html#64732

Answer 2

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
import java.beans.*;
import java.io.*;
import javax.swing.event.*;
import java.beans.ExceptionListener;public class DynamicTreeDemo extends JPanel implements ExceptionListener {
    private int newNodeSuffix = 1;
    String xmlFname = "test.xml";
    DynamicTree treePanel = new DynamicTree();    public DynamicTreeDemo(JFrame frame) {
        populateTree(treePanel);
        JButton addButton = new JButton("Add");
        addButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                treePanel.addObject("New Node " + newNodeSuffix++);
            }
        });        JButton removeButton = new JButton("Remove");
        removeButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                treePanel.removeCurrentNode();
            }
        });        JButton clearButton = new JButton("Clear");
        clearButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                treePanel.clear();
            }
        });
JButton saveButton = new JButton("Save");
        saveButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
             try
             {
             XMLEncoder xe = new XMLEncoder(new BufferedOutputStream(        
             new FileOutputStream( xmlFname ) ) );
             xe.setExceptionListener(DynamicTreeDemo.this);
             xe.writeObject( treePanel.rootNode );    
             xe.flush();    
             xe.close();
            }
            catch(Exception ex)
            {ex.printStackTrace();}
            }
        });
        JButton loadButton = new JButton("load");
        loadButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                try
                {
                 treePanel.clear();
             XMLDecoder xe = new XMLDecoder(new FileInputStream(xmlFname));
             xe.setExceptionListener(DynamicTreeDemo.this);
             treePanel.rootNode = (DefaultMutableTreeNode)xe.readObject();
             xe.close();
             treePanel.reload();            
                }
                catch(Exception ex)
            {ex.printStackTrace();}
            }
        });        
        setLayout(new BorderLayout());
        treePanel.setPreferredSize(new Dimension(300, 150));
        add(treePanel, BorderLayout.CENTER);
        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(0,1));
        panel.add(addButton);
        panel.add(removeButton);
        panel.add(clearButton);
        panel.add(saveButton);
        panel.add(loadButton);
        add(panel, BorderLayout.EAST);
    }
    public void populateTree(DynamicTree treePanel) {
        String p1Name = new String("Parent 1");
        String p2Name = new String("Parent 2");
        String c1Name = new String("Child 1");
        String c2Name = new String("Child 2");
        DefaultMutableTreeNode p1, p2;
        p1 = treePanel.addObject(null, p1Name);
        p2 = treePanel.addObject(null, p2Name);
        treePanel.addObject(p1, c1Name);
        treePanel.addObject(p1, c2Name);
        treePanel.addObject(p2, c1Name);
        treePanel.addObject(p2, c2Name);
    }    public static void main(String[] args) {
        JFrame frame = new JFrame("Save tree to xml and load from that xml file:masterz contributes the save/load part");
        Container contentPane = frame.getContentPane();
        contentPane.setLayout(new GridLayout(1,1));
        contentPane.add(new DynamicTreeDemo(frame));
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        frame.pack();
        frame.setVisible(true);
    }
public void exceptionThrown(Exception e) {
e.printStackTrace();
}
}
class DynamicTree extends JPanel {
    public DefaultMutableTreeNode rootNode;
    public DefaultTreeModel treeModel;
    protected JTree tree;
    private Toolkit toolkit = Toolkit.getDefaultToolkit();
    public DynamicTree() {
        rootNode = new DefaultMutableTreeNode("Root Node");
reload();
    }
    public void clear() {
        rootNode.removeAllChildren();
        treeModel.reload();
    }
public void reload()
{
        treeModel = new DefaultTreeModel(rootNode);
        tree = new JTree(treeModel);
        tree.setEditable(true);
        tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION);
        tree.setShowsRootHandles(true);
        this.removeAll();
        JScrollPane scrollPane = new JScrollPane(tree);
        setLayout(new GridLayout(1,0));
        add(scrollPane);
invalidate();
repaint();
validate();
}
    /** Remove the currently selected node. */
    public void removeCurrentNode() {
        TreePath currentSelection = tree.getSelectionPath();
        if (currentSelection != null) {
            DefaultMutableTreeNode currentNode = (DefaultMutableTreeNode)
                         (currentSelection.getLastPathComponent());
            MutableTreeNode parent = (MutableTreeNode)(currentNode.getParent());
            if (parent != null) {
                treeModel.removeNodeFromParent(currentNode);
                return;
            }
        } 
    }
    /** Add child to the currently selected node. */
    public DefaultMutableTreeNode addObject(Object child) {
        DefaultMutableTreeNode parentNode = null;
        TreePath parentPath = tree.getSelectionPath();        if (parentPath == null) {
            parentNode = rootNode;
        } else {
            parentNode = (DefaultMutableTreeNode)
                         (parentPath.getLastPathComponent());
        }
        return addObject(parentNode, child, true);
    }
    public DefaultMutableTreeNode addObject(DefaultMutableTreeNode parent,
                                            Object child) {
        return addObject(parent, child, false);
    }
    public DefaultMutableTreeNode addObject(DefaultMutableTreeNode parent,
                                            Object child, 
                                            boolean shouldBeVisible) {
        DefaultMutableTreeNode childNode = 
                new DefaultMutableTreeNode(child);        if (parent == null) {
            parent = rootNode;
        }
        treeModel.insertNodeInto(childNode, parent, 
                                 parent.getChildCount());        
        if (shouldBeVisible) {
            tree.scrollPathToVisible(new TreePath(childNode.getPath()));
        }
        return childNode;
    }}