BufferedImage target = new BufferedImage(syswidth,sysheight,BufferedImage.TYPE_3BYTE_BGR); 
AffineTransform transform = new AffineTransform();
transform.setToScale(sx,sy);
//操作
AffineTransformOp op = new AffineTransformOp(transform,null); 
op.filter(source,target);

------解决方案--------------------
public static Icon getFixedBoundIcon(String filePath,int height,int width) throws Exception
	{
		double ratio = 0.0;
		File file = new File(filePath);
		if(!file.isFile())
		{
			throw new Exception(file+" is not image file error in getFixedBoundIcon!");
		}
		Icon ret = new ImageIcon(filePath);
		BufferedImage bi = ImageIO.read(file);
		if(bi.getHeight()>height||bi.getWidth()>width)
		{
			if(bi.getHeight()>bi.getWidth())
			{
				ratio = (new Integer(height)).doubleValue()/bi.getHeight();
			}
			else  
			{
				ratio = (new Integer(width)).doubleValue()/bi.getWidth();
			}
			int lastLength = filePath.lastIndexOf(".");
			String subFilePath = filePath.substring(0,lastLength);
			String fileType = filePath.substring(lastLength);
			File zoomFile = new File(subFilePath+fileType);
			Image temp = bi.getScaledInstance(width, height, bi.SCALE_SMOOTH);
			AffineTransformOp op = new AffineTransformOp(AffineTransform.getScaleInstance(ratio, ratio),null);
			temp = op.filter(bi, null);
			ImageIO.write((BufferedImage)temp, "jpg", zoomFile);
			ret = new ImageIcon(zoomFile.getPath());
		}
		return ret;
	}

------解决方案--------------------

HTML code

http://blog.csdn.net/fancyerII/archive/2010/08/25/5837991.aspx