test.java

《Java2图形设计卷II：Swing》配套光盘源码

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;

public class Test extends JApplet {
	public Test() {
		Container contentPane = getContentPane();
		JTextArea textArea = new JTextArea(
		  "File choosers, like option panes, are lightweight\n" +
		  "components that\n" +
		  "are meant to be placed ...");

		textArea.setCaret(new BoxHighlightingCaret());
		textArea.setFont(new Font("Dialog", Font.ITALIC, 24));

		contentPane.add(new JScrollPane(textArea), 
						BorderLayout.CENTER);
	}
}
class BoxHighlightingCaret extends DefaultCaret {
	private static BoxHighlighterPainter painter = 
								new BoxHighlighterPainter(null);

	public Highlighter.HighlightPainter getSelectionPainter(){
		return painter;
	}
	static class BoxHighlighterPainter 
		extends DefaultHighlighter.DefaultHighlightPainter {
		private Color color;

		public BoxHighlighterPainter(Color color) {
			super(color);
			this.color = color;
		}
		public Shape paintLayer(Graphics g, int p0, int p1, 
								Shape shape, JTextComponent comp,
								View view) {
			Rectangle b = shape.getBounds();

			try {
				g.setColor(getColor(comp));

				Rectangle r1 = comp.modelToView(p0);
				Rectangle r2 = comp.modelToView(p1);

				g.drawRect(r1.x, r1.y,  	 // x,y
							r2.x - r1.x - 1, // width
							r1.height - 1);  // height
			}
			catch(BadLocationException ex) {
				ex.printStackTrace();
			}
			return b;
		}
		private Color getColor(JTextComponent comp) {
			return color != null ? color : 
					   comp.getSelectionColor();
		}
	}
}