display content based on uploaded files extention

I am trying to find some way where I can control what content are shown based on uploaded files. For example:
If the uploaded file is a .jpg or .png image, somewhere in the body of the article will display the thumbnail of the uploaded image. If the uploaded file is a mp3, the article will be embeded a player.

It is kinda like to display file icon based on file extension of file value field. But I don't know how to do it. Can anyone offer a snippet?

Thanks a lot!