JTextArea中显示LineNumber[组图]

　　//package tryLineNumber;

　　import java.awt.BorderLayout;
　　import java.awt.Dimension;
　　import java.awt.Graphics;
　　import java.awt.Point;

　　
　　import javax.swing.JFrame;
　　import javax.swing.JTextArea;
　　import javax.swing.JPanel;
　　import javax.swing.JScrollPane;
　　//import javax.swing.JTextPane;
　　import javax.swing.text.BadLocationException;
　　import javax.swing.text.Document;

　　
　　/**
　　  * A class illustrating running line number count on JTextPane. Nothing
　　is painted on the pane itself,
　　  * but a separate JPanel handles painting the line numbers.<br>
　　  *
　　  * @author Daniel Sj?blom<br>
　　  * Created on Mar 3, 2004<br>
　　  * Copyright (c) 2004<br>
　　  * @version 1.0<br>
　　  */
　　public class LineNr extends JPanel
　　{
　　        // for this simple experiment, we keep the pane + scrollpane as members.
　　        //JTextPane pane;
　　        JTextArea pane;
　　        JScrollPane scrollPane;

　　
　　        public LineNr()
　　        {
　　                super();
　　                setMinimumSize(new Dimension(30, 30));
　　                setPreferredSize(new Dimension(30, 30));
　　                setMinimumSize(new Dimension(30, 30));
　　                //pane = new JTextPane() // we need to override paint so that the linenumbers stay in sync
　　                pane = new JTextArea()
　　                {
　　                        public void paint(Graphics g)
　　                        {
　　                                super.paint(g);
　　                                LineNr.this.repaint();
　　                        }
　　                };
　　                scrollPane = new JScrollPane(pane);