Generate MD5 hash of a file while being as Groovy as possible.

md5.groovy

def generateMD5( File file ) {
  def digest = java.security.MessageDigest.getInstance("MD5")
  file.eachByte( 4096 ) { buffer, length ->
    digest.update( buffer, 0, length )
  }
  new BigInteger(1, digest.digest()).toString(16).padLeft(32, '0')
}

The hex encoding can also be done like this:

digest.digest().encodeHex() as String

I'd say

def generateMD5(File file) {
   file.withInputStream {
      new DigestInputStream(it, MessageDigest.getInstance('MD5')).withStream {
         it.eachByte {}
         it.messageDigest.digest().encodeHex() as String
      }
   }
}

import java.nio.file.Path

Path.metaClass.getMd5 << { ->
   def digest = java.security.MessageDigest.getInstance("MD5")
   delegate.withInputStream { stream ->
       stream.eachByte 4096, { buffer, length ->
       digest.update( buffer, 0, length )
     }
  }
  digest.digest().encodeHex() as String
}

File.metaClass.getMd5 << { -> delegate.toPath().md5 }

def f = new File('/Users/pwg947/incoming_transactions.tsv')

f.md5