读取xml文件小程序

package com.test;

import org.w3c.dom.*;

import javax.swing.*;
import javax.swing.event.TreeModelListener;
import javax.swing.filechooser.FileNameExtensionFilter;
import javax.swing.table.AbstractTableModel;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.TreeModel;
import javax.swing.tree.TreePath;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.awt.*;
import java.io.File;

/**
 * 以树形结构显示xml文档
 */
public class TreeViewer {
    public static void main(String[] args) {
        EventQueue.invokeLater(() -> {
            JFrame frame = new DOMTreeFrame();
            frame.setTitle("TreeViewer");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setVisible(true);
        });
    }
}

class DOMTreeFrame extends JFrame{
    private static final int DEFAULT_WIDTH = 400;
    private static final int DEFAULT_HEIGHT = 400;

    private DocumentBuilder builder;

    public DOMTreeFrame() {
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

        JMenu fileMenu = new JMenu("File");
        JMenuItem openItem = new JMenuItem("Open");
        openItem.addActionListener(event -> openFile());
        fileMenu.add(openItem);

        JMenuItem exitItem = new JMenuItem("Exit");
        exitItem.addActionListener(event -> System.exit(0));
        fileMenu.add(exitItem);

        JMenuBar menuBar = new JMenuBar();
        menuBar.add(fileMenu);
        setJMenuBar(menuBar);

    }

    /**
     * 打开一个文件并加载文档
     */
    public void openFile(){
        JFileChooser chooser = new JFileChooser();
        chooser.setCurrentDirectory(new File("dom"));
        chooser.setFileFilter(new FileNameExtensionFilter("XML Files","xml"));
        int r = chooser.showOpenDialog(this);
        if(r!=JFileChooser.APPROVE_OPTION) return;
        final File file = chooser.getSelectedFile();

        new SwingWorker<Document,Void>(){

            @Override
            protected Document doInBackground() throws Exception {
                if (builder == null){
                    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                    builder = factory.newDocumentBuilder();
                }
                return builder.parse(file);
            }

            protected void done(){
                try {
                    Document doc = get();
                    JTree tree = new JTree(new DOMTreeModel(doc));
                    tree.setCellRenderer(new DOMTreeCellRenderer());
                    setContentPane(new JScrollPane(tree));
                    validate();
                } catch (Exception e) {
                    e.printStackTrace();
                    JOptionPane.showMessageDialog(DOMTreeFrame.this, e);
                }
            }
        }.execute();

    }
}
class DOMTreeModel implements TreeModel {

    private Document doc;

    public DOMTreeModel(Document doc) {
        this.doc = doc;
    }

    @Override
    public Object getRoot() {
        return doc.getDocumentElement();
    }

    @Override
    public Object getChild(Object parent, int index) {
        Node node = (Node) parent;
        NodeList list = node.getChildNodes();
        return list.item(index);
    }

    @Override
    public int getChildCount(Object parent) {
        Node node = (Node) parent;
        NodeList list = node.getChildNodes();
        return list.getLength();
    }

    @Override
    public boolean isLeaf(Object node) {
        return getChildCount(node) == 0;
    }

    @Override
    public void valueForPathChanged(TreePath path, Object newValue) {

    }

    @Override
    public int getIndexOfChild(Object parent, Object child) {
        Node node = (Node) parent;
        NodeList list = node.getChildNodes();
        for (int i = 0; i < list.getLength(); i++) {
            if(getChild(node,i) == child) return i;
        }
        return -1;
    }

    @Override
    public void addTreeModelListener(TreeModelListener l) {

    }

    @Override
    public void removeTreeModelListener(TreeModelListener l) {

    }
}
class DOMTreeCellRenderer extends DefaultTreeCellRenderer{

    @Override
    public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded,
                                                  boolean leaf, int row, boolean hasFocus) {
        Node node = (Node) value;
        if(node instanceof Element) return elementPanel((Element) node);
        super.getTreeCellRendererComponent(tree, value, selected, expanded, leaf, row, hasFocus);
        if (node instanceof CharacterData) setText(characterString((CharacterData) node));
        else setText(node.getClass()+": "+node.toString());
        return this;
    }

    public static JPanel elementPanel(Element e){
        JPanel panel = new JPanel();
        panel.add(new JLabel("Element:"+e.getTagName()));
        final NamedNodeMap map = e.getAttributes();
        panel.add(new JTable(new AbstractTableModel() {
            @Override
            public int getRowCount() {
                return map.getLength();
            }

            @Override
            public int getColumnCount() {
                return 2;
            }

            @Override
            public Object getValueAt(int rowIndex, int columnIndex) {
                return columnIndex == 0 ? map.item(rowIndex).getNodeName() : map.item(rowIndex).getNodeValue();
            }
        }));
        return panel;
    }

    private static String characterString(CharacterData node){
        StringBuilder builder = new StringBuilder(node.getData());
        for (int i = 0; i < builder.length(); i++) {
            if(builder.charAt(i) == '\r'){
                builder.replace(i, i + 1, "\\r");
                i++;
            }else if(builder.charAt(i) == '\n'){
                builder.replace(i, i + 1, "\\n");
                i++;
            }else if(builder.charAt(i) == '\t'){
                builder.replace(i, i + 1, "\\t");
                i++;
            }

        }
        if(node instanceof CDATASection) builder.insert(0, "CDATASection:");
        else if (node instanceof Text) builder.insert(0, "Text:");
        else if (node instanceof Comment) builder.insert(0, "Comment:");
        return builder.toString();
    }

}