Example of hashing function

Utils.java

package com.adidas.fdp;

import com.google.common.collect.ImmutableMap;
import org.apache.commons.codec.digest.DigestUtils;

import static org.apache.commons.codec.digest.MessageDigestAlgorithms.*;

public class Utils {

  private static final ImmutableMap<String, Hasher> HASHER_MAP =
    new ImmutableMap.Builder<String, Hasher>()
      .put(SHA_256, new Utils.Sha256())
      .put(SHA3_256, new Utils.Sha3_256())
      .put(SHA_512, new Utils.Sha512())
      .put(SHA3_512, new Utils.Sha3_512())
      .build();

  public static class Sha256 implements Hasher {
    @Override
    public String apply(final String input) {
      return DigestUtils.sha256Hex(input);
    }
  }

  public static class Sha3_256 implements Hasher {
    @Override
    public String apply(final String input) {
      return DigestUtils.sha3_256Hex(input);
    }
  }

  public static class Sha512 implements Hasher {
    @Override
    public String apply(final String input) {
      return DigestUtils.sha512Hex(input);
    }
  }

  public static class Sha3_512 implements Hasher {
    @Override
    public String apply(final String input) {
      return DigestUtils.sha3_512Hex(input);
    }
  }

  public static void checkAlgorithm(String algo) {
    String SupportedAlgorithm = String.join(", ", HASHER_MAP.keySet());
    if (HASHER_MAP.get(algo) == null) {
      throw new KsqlFunctionException("Unsupported Algorithm "
        + algo + "- The supported algorithm are the following: " + SupportedAlgorithm);
    }
  }

  public static String hashString(String str, String algo) {
    return HASHER_MAP.get(algo).apply(str);
  }
}