how to get the file signature in java? for example a pdf file has signature 25 50 44 46 ..how to get it using java?
Those are the first bytes in the file, yes? Just open a FileInputStream with that file and read the first 4 bytes into a 4 byte array where you can check the values. Then close the stream. https://docs.oracle.com/javase/8/docs/api/java/io/FileInputStream.html ps: Although those bytes correspond to "%PDF" in ASCII, don't be tempted … Read More
I think the original post (with example) is pretty clear that it's the signature in the first few bytes he wants, but yes, you are right that the the Java API includes classes to get a hash ([MessageDigest](https://docs.oracle.com/javase/8/docs/api/java/security/MessageDigest.html)) for a file very easily. Read More
Edited by overwraith: more accuracy