java 在JTextArea中实现Redo和Undo功能

[java]代码库

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.event.UndoableEditEvent;
import javax.swing.text.Document;
import javax.swing.undo.UndoManager;

/**
 * 在JTextArea中实现Redo和Undo功能
 * @author 五斗米 <如转载请保留作者和出处>
 * @blog <a href="http://blog.csdn.net/mq612">http://blog.csdn.net/mq612
 */

public class Test extends JFrame {

 private static final long serialVersionUID = -2397593626990759111L;

 private JPanel pane = null;

 private JButton undo = null, redo = null;

 private JScrollPane sPane = null;

 private JTextArea text = null;

 private Document doc = null;

 private UndoManager undomang = null;

 public Test() {
  super("Redo and Undo");
  undomang = new UndoManager(){
   private static final long serialVersionUID = -5960092671497318496L;
   public void undoableEditHappened(UndoableEditEvent e) {
    this.addEdit(e.getEdit());
   }
  };
  text = new JTextArea();
  doc = text.getDocument();
  redo = new JButton(">>");
  undo = new JButton("<<");
  undo.addActionListener(new ActionListener() {
   public void actionPerformed(ActionEvent arg0) {
    if (undomang.canUndo())
     undomang.undo();
   }
  });
  redo.addActionListener(new ActionListener() {
   public void actionPerformed(ActionEvent e) {
    if (undomang.canRedo())
     undomang.redo();
   }
  });
  pane = new JPanel();
  pane.add(undo);
  pane.add(redo);
  doc.addUndoableEditListener(undomang);
  sPane = new JScrollPane(text);
  this.getContentPane().add(sPane);
  this.getContentPane().add(pane, BorderLayout.NORTH);
  this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  this.setSize(300, 200);
  this.setVisible(true);
 }

 public static void main(String args[]) {
  new Test();
 }

}

//源代码片段来自云代码http://yuncode.net