JavaFX: Get format (PNG, JPG..) of an image?

Question

I am creating an application that for some reasons shall only accept PNG images.

How can I check if an image is really a PNG image? Currently I am using the JavaFX 2 Image class to load the image.

Thanks for any hint!

Answer 1

I do this currently in my own application by confirming the file's Mime Type before I process it. There are several SO threads suggesting how to obtain Mime Types in Java.

• Getting A File's Mime Type In Java
• java library to find the mime type from file content

Answer 2

If you don't trust the filename, a simple check is to read the first 8 bytes (with FileInputStream), and check that they correspond to the PNG signature (related: https://stackoverflow.com/a/10555053/277304)