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

Try using the java.security.MessageDigest Class. For example:

public void givenFile_generatingChecksum_thenVerifying()

throws NoSuchAlgorithmException, IOException {

String filename = "src/test/resources/test_md5.txt";

String checksum = "5EB63BBBE01EEED093CB22BB8F5ACDC3";

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

md.update(Files.readAllBytes(Paths.get(filename)));

byte[] digest = md.digest();

String myChecksum = DatatypeConverter

.printHexBinary(digest).toUpperCase();

assertThat(myChecksum.equals(checksum)).isTrue();

}

Source: https://www.baeldung.com/java-md5