xpathtest.java

此文档包含有AOP

package test.xml;

import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathFactory;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.xml.namespace.*;
import javax.xml.parsers.*;
import javax.xml.xpath.*;
import org.w3c.dom.*;
import org.xml.sax.*;

/**
 * This program evaluates XPath expressions
 */
public class XPathTest {
	public static void main(String[] args) {
		JFrame frame = new XPathFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setVisible(true);
	}
}

/**
 * This frame shows an XML document, a panel to type an XPath expression, and a
 * text field to display the result.
 */
class XPathFrame extends JFrame {
	public XPathFrame() {
		setTitle("XPathTest");
		JMenu fileMenu = new JMenu("File");
		JMenuItem openItem = new JMenuItem("Open");
		openItem.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent event) {
				openFile();
			}
		});
		fileMenu.add(openItem);
		JMenuItem exitItem = new JMenuItem("Exit");
		exitItem.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent event) {
				System.exit(0);
			}
		});
		fileMenu.add(exitItem);
		JMenuBar menuBar = new JMenuBar();
		menuBar.add(fileMenu);
		setJMenuBar(menuBar);
		ActionListener listener = new ActionListener() {
			public void actionPerformed(ActionEvent event) {
				evaluate();
			}
		};
		expression = new JTextField(20);
		expression.addActionListener(listener);
		JButton evaluateButton = new JButton("Evaluate");
		evaluateButton.addActionListener(listener);
		typeCombo = new JComboBox(new Object[] { "STRING", "NODE", "NODESET",
				"NUMBER", "BOOLEAN" });
		typeCombo.setSelectedItem("STRING");
		JPanel panel = new JPanel();
		panel.add(expression);
		panel.add(typeCombo);
		panel.add(evaluateButton);
		docText = new JTextArea(10, 40);
		result = new JTextField();
		result.setBorder(new TitledBorder("Result"));
		add(panel, BorderLayout.NORTH);
		add(new JScrollPane(docText), BorderLayout.CENTER);
		add(result, BorderLayout.SOUTH);
		try {
			DocumentBuilderFactory factory = DocumentBuilderFactory
					.newInstance();
			builder = factory.newDocumentBuilder();
		} catch (ParserConfigurationException e) {
			JOptionPane.showMessageDialog(this, e);
		}
		XPathFactory xpfactory = XPathFactory.newInstance();
		path = xpfactory.newXPath();
		pack();
	}

	/**
	 * Open a file and load the document.
	 */
	public void openFile() {
		JFileChooser chooser = new JFileChooser();
		chooser.setCurrentDirectory(new File("."));
		chooser.setFileFilter(new javax.swing.filechooser.FileFilter() {
			public boolean accept(File f) {
				return f.isDirectory()
						|| f.getName().toLowerCase().endsWith(".xml");
			}

			public String getDescription() {
				return "XML files";
			}
		});
		int r = chooser.showOpenDialog(this);
		if (r != JFileChooser.APPROVE_OPTION)
			return;
		File f = chooser.getSelectedFile();
		try {
			byte[] bytes = new byte[(int) f.length()];
			new FileInputStream(f).read(bytes);
			docText.setText(new String(bytes));
			doc = builder.parse(f);
		} catch (IOException e) {
			JOptionPane.showMessageDialog(this, e);
		} catch (SAXException e) {
			JOptionPane.showMessageDialog(this, e);
		}
	}

	public void evaluate() {
		try {
			String typeName = (String) typeCombo.getSelectedItem();
			QName returnType = (QName) XPathConstants.class.getField(typeName)
					.get(null);
			Object evalResult = path.evaluate(expression.getText(), doc,
					returnType);
			if (typeName.equals("NODESET")) {
				NodeList list = (NodeList) evalResult;
				StringBuilder builder = new StringBuilder();
				builder.append("{");
				for (int i = 0; i < list.getLength(); i++) {
					if (i > 0)
						builder.append(", ");
					builder.append("" + list.item(i));
				}
				builder.append("}");
				result.setText("" + builder);
			} else
				result.setText("" + evalResult);
		} catch (XPathExpressionException e) {
			result.setText("" + e);
		} catch (Exception e) // reflection exception
		{
			e.printStackTrace();
		}
	}

	private DocumentBuilder builder;
	private Document doc;
	private XPath path;
	private JTextField expression;
	private JTextField result;
	private JTextArea docText;
	private JComboBox typeCombo;
}