生成缩列图的java工具类

附件里边是生成缩列图的工具类，希望有用

代码如下：

/**
 * 生成缩略图类
 */
import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;

public class ThumbnailGenerator {
	/**
	 * 转换图为缩略图
	 * @param originalFile  原图路径
	 * @param thumbnailFile 缩略图路径
	 * @param thumbWidth 缩略图宽度
	 * @param thumbHeight 缩略图高度
	 * @param quality 
	 * @throws Exception
	 */
	public void transform(String originalFile, String thumbnailFile, int thumbWidth, int thumbHeight, int quality) throws Exception 
	{
		Image image = javax.imageio.ImageIO.read(new File(originalFile));
	    
	    double thumbRatio = (double)thumbWidth / (double)thumbHeight;
	    int imageWidth    = image.getWidth(null);
	    int imageHeight   = image.getHeight(null);
	    double imageRatio = (double)imageWidth / (double)imageHeight;
	    if (thumbRatio < imageRatio) 
	    {
	    	thumbHeight = (int)(thumbWidth / imageRatio);
	    } 
	    else 
	    {
	      	thumbWidth = (int)(thumbHeight * imageRatio);
	    }
	    
		if(imageWidth < thumbWidth && imageHeight < thumbHeight)
		{
			thumbWidth = imageWidth;
			thumbHeight = imageHeight;
		}
		else if(imageWidth < thumbWidth)
			thumbWidth = imageWidth;
		else if(imageHeight < thumbHeight)
			thumbHeight = imageHeight;

	    BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);
	    Graphics2D graphics2D = thumbImage.createGraphics();
	    graphics2D.setBackground(Color.WHITE);
    	graphics2D.setPaint(Color.WHITE); 
    	graphics2D.fillRect(0, 0, thumbWidth, thumbHeight);
	    graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
	    graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);
	    
		javax.imageio.ImageIO.write(thumbImage, "JPG", new File(thumbnailFile));
	}
}