Extracting exif header from image (J2ME)

Question

I'm developing a J2ME app which includes a file browser. I need to display the thumbnails of the images in the folder. I tried resizing the images, but it won't work if the file is large.
How can I get the thumbnail from the exif header of the image. Will be helpful if you could post a link or something where I can learn about it or download sample codes.

Thanks in advance.