FileHashUtility

package me.rabrg.thor.utility;

import java.io.IOException;
import java.io.RandomAccessFile;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public final class FileHashUtility {

    private final MessageDigest digest;

    private FileHashUtility() throws NoSuchAlgorithmException {
        digest = MessageDigest.getInstance("SHA-256");
    }

    public byte[] hash(final String directory) throws IOException {
        try (final RandomAccessFile file = new RandomAccessFile(directory, "r")) {
            final long length = file.length();
            if (length != (int) length) {
                throw new IllegalArgumentException("Specified file is too large");
            }
            final byte[] data = new byte[(int) length];
            file.readFully(data);

            digest.update(data);
            final byte[] hash = digest.digest();
            digest.reset();
            return hash;
        }
    }
}