Getting a File's MD5 Checksum in Java

Question

I am looking to use Java to get the MD5 checksum of a file. I was really surprised but I haven't been able to find anything that shows how to get the MD5 checksum of a file.

How is it done?

Answer 1

You can try java.security.DigestInputStream it's an input stream decorator so that you can calculate the digest while using the input stream as you usually would, instead of having to get an additional pass over the data.

Here's the Syntax:

MessageDigest md = MessageDigest.getInstance("MD5");

try (InputStream is = Files.newInputStream(Paths.get("file.txt"));

     DigestInputStream dis = new DigestInputStream(is, md)) 

byte[] digest = md.digest();