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voucher NO. generator

There is a newer version: 0.0.7

package com.github.bingoohuang.voucherno;


import lombok.SneakyThrows;

import java.nio.charset.Charset;
import java.security.MessageDigest;

/**
 * This program refers to the java-bloomfilter,you can get its details form https://github.com/MagnusS/Java-BloomFilter.
 * You have any questions about this program please put issues on github to
 * https://github.com/wxisme/bloomfilter
 */
public abstract class MessageDigestUtils {
    private static final String MD5 = "MD5";//SHA1,SHA256
    public static final Charset UTF8 = Charset.forName("UTF-8"); // encoding used for storing hash values as strings


    private static final MessageDigest messageDigest = createMd5();

    @SneakyThrows
    public static MessageDigest createMd5() {
        return MessageDigest.getInstance(MD5);
    }

    /**
     * Generates digests based on the contents of an array of bytes and splits the result into 4-byte int's and store them in an array. The
     * digest function is called until the required number of int's are produced. For each call to digest a salt
     * is prepended to the data. The salt is increased by 1 for each call.
     *
     * @param data   specifies input data.
     * @param hashes number of hashes/int's to produce.
     * @return array of int-sized hashes
     */
    public static int[] createHashes(byte[] data, int hashes) {
        int[] result = new int[hashes];

        int k = 0;
        byte salt = 0;
        while (k < hashes) {
            byte[] digest;
            synchronized (messageDigest) {
                messageDigest.update(salt);
                salt++;
                digest = messageDigest.digest(data);
            }

            for (int i = 0; i < digest.length / 4 && k < hashes; i++) {
                int h = 0;
                for (int j = (i * 4); j < (i * 4) + 4; j++) {
                    h <<= 8;
                    h |= ((int) digest[j]) & 0xFF;
                }
                result[k] = h;
                k++;
            }
        }
        return result;
    }

}