catalogimage.java

来自「java编程开发技巧与实例的编译测试通过的所有例程」· Java 代码 · 共 49 行

import java.net.*;
import java.awt.*;

public class CatalogImage extends Canvas
{
	private Image image = null;
	public CatalogImage()
	{
		super();
	}
	public void setImage(URL base, String name)
	{
		try
		{
			URL url	=	new URL(base, name);
			image = Toolkit.getDefaultToolkit().getImage(url);
			MediaTracker tracker	=	new MediaTracker(this);
			tracker.addImage(image, 0);
			tracker.waitForAll();
		}
		catch	(Exception e)
		{
			System.err.println("Image not available or not loaded" + e);
			image = null;
		}
		repaint();
	}
	public Dimension getPreferredSize()
	{
		return new Dimension(100, 100);
	}
	public void paint(Graphics g)
	{
		g.drawRect(0, 0, getSize().width - 1, getSize().height - 1);
		if((image != null) && (image.getWidth(this) > 0))
		{
			int x = (getSize().width - image.getWidth(this)) / 2;
			int y = (getSize().height - image.getHeight(this)) / 2;
			g.drawImage(image, x, y, this);
		}
		else
		{
			g.setColor(Color.red);
			g.drawLine(0, 0, getSize().width, getSize().height);
			g.drawLine(getSize().width, 0, 0, getSize().height);
		}
	}
}