多页tiff转jpg

最近好几个站友求这段代码，就放这里，免得每次发邮件了。

import java.awt.image.RenderedImage;
import java.io.*;

import com.sun.media.jai.codec.*;

/**
* @version 1.0 2008-1-14 12:09:10
*/
public class TiffUtil
{
   public static final String TIFF = "TIFF";
   public static final String JPEG = "JPEG";

   public static int getTotalPageNumber(File file)
           throws IOException
   {
       SeekableStream seekableStream = new FileSeekableStream(file);
       TIFFDecodeParam param = new TIFFDecodeParam();
       ImageDecoder dec = ImageCodec.createImageDecoder(TIFF, seekableStream, param);
       return dec.getNumPages();
   }

   /**
    * 获取tiff文件中的某页的图像，页号从0开始
    *
    * @param tiffInputStream tiff输入流
    * @param pageNum tiff文件中的某页号，从0开始
    * @return tiff中的某页图象
    * @throws IOException;
    */
   public static RenderedImage getSinglePageRenderImage(InputStream tiffInputStream, int pageNum)
           throws IOException
   {
       int page = pageNum - 1;
       TIFFDecodeParam param = new TIFFDecodeParam();
       ImageDecoder dec = ImageCodec.createImageDecoder(TIFF, tiffInputStream, param);
       int numPages = dec.getNumPages();
       if (page < 0 || page >= numPages) {
           throw new IndexOutOfBoundsException();
       }
       return dec.decodeAsRenderedImage(page);
   }

   /**
    * 获取tiff文件中的某页的图像，页号从0开始
    *
    * @param file tiff文件
    * @param pageNum tiff文件中的某页号，从0开始
    * @return tiff中的某页图象
    * @throws IOException;
    */
   public static RenderedImage getSinglePageRenderImage(File file, int pageNum)
           throws IOException
   {
       int page = pageNum - 1;
       TIFFDecodeParam param = new TIFFDecodeParam();
       ImageDecoder dec = ImageCodec.createImageDecoder(TIFF, file, param);
       int numPages = dec.getNumPages();
       if (page < 0 || page >= numPages) {
           throw new IndexOutOfBoundsException();
       }
       return dec.decodeAsRenderedImage(page);
   }

   public static void main(String[] args)
           throws IOException
   {
       File file = new File("n:/tmp/a.tiff");
       RenderedImage image = TiffUtil.getSinglePageRenderImage(file, 1);
       JPEGEncodeParam param = new JPEGEncodeParam();
       param.setQuality(0.075f);

       try {
           OutputStream os = new FileOutputStream("n:/tmp/a.jpg");
           ImageEncoder imageEncoder = ImageCodec.createImageEncoder(JPEG, os, param);
           imageEncoder.encode(image);
           os.close();
       }
       catch (Exception e) {
           e.printStackTrace();
       }
   }
}