exif 修改出错

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.OutputStream;



import mediautil.gen.Rational;

import mediautil.image.jpeg.Entry;

import mediautil.image.jpeg.Exif;

import mediautil.image.jpeg.LLJTran;

import mediautil.image.jpeg.LLJTranException;





public class exifTestwrit {

	/**

    * 将照片中的信息进行重写

    * @param args

    * @throws Exception

    */

   public static void main(String[] args) throws Exception {

	   LLJTran llj = new LLJTran(new File("E:\\dd.jpg"));

       readImage(llj, true, LLJTran.READ_INFO, 0, 0);

       // llj.closeInternalInputStream();

       String newTime = "";

       Exif exif = (Exif) llj.getImageInfo();



       Entry entry = exif.getTagValue(Exif.DATETIME, true);

       if(entry != null)

           entry.setValue(0, "1998:08:18 11:15:00");

       entry = exif.getTagValue(Exif.DATETIMEORIGINAL, true);

       if(entry != null)

           entry.setValue(0, "1998:08:18 11:15:00");

       entry = exif.getTagValue(Exif.DATETIMEDIGITIZED, true);

       if(entry != null)

           entry.setValue(0, "1998:08:18 11:15:00");

       entry = exif.getTagValue(Exif.ORIENTATION, true);

       System.out.println("Orient Entry = " + entry);

       if(entry != null)

           entry.setValue(0, new Integer(6));



       llj.refreshAppx();



       // FileInputStream fip = new FileInputStream("Img_1217.jpg");

       FileOutputStream nhOp = new FileOutputStream("c:\\new_2.jpg");

       llj.xferInfo(null, nhOp, LLJTran.REPLACE, LLJTran.REPLACE);

       // fip.close();

       nhOp.close();

   }

   public static void readImage(LLJTran llj, boolean keep_appxs, int stage1, int stage2, int stage3)throws LLJTranException

   {

   if(stage1 != 0)

       llj.read(stage1, keep_appxs);

   if(stage2 != 0)

   llj.read(stage2, keep_appxs);

   if(stage3 != 0)

   llj.read(stage3, keep_appxs);

   System.out.println("Successfully Read Image");

   }

}

错误为
Exception in thread "main" java.lang.ClassCastException: mediautil.image.jpeg.JPEG cannot be cast to mediautil.image.jpeg.Exif
at exifTestwrit.main(exifTestwrit.java:27)
但是去查了api
getImageInfo的方法说明是这样的

public AbstractImageInfo getImageInfo()

Returns an instance of the Image Header Info. The Class of the Object returned is a specific implementation of AbstractImageInfo like Exif. If there is no specific Image Header Information like Exif an instance of JPEG containing basic Image Info is returned.

Returns:
Image Header Information

然后看了exif 的继承关系确实是
java.lang.Object
extended by mediautil.gen.BasicIo
extended by mediautil.image.jpeg.BasicJpegIo
extended by mediautil.image.jpeg.AbstractImageInfo<LLJTran>
extended by mediautil.image.jpeg.Exif
不明白为什么会报错