ImageIO - get image type and exif data

Question

Given some source file (or more generic - input stream), I need to find out

• is it an image
• if it is an image, then retrieve its type (png/jpeg/gif/etc

Answer 1

Easy answer: Use https://github.com/drewnoakes/metadata-extractor/

If you're crazy/brave/curious, you could get image type from the stream by reading the first few bytes (these are magic numbers). I believe the exif is generally at the start of the stream too.