package com.dxhy.common.util;

import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5 {

    /**
     * 获得随机数字
     * 
     * @param num
     *            位数
     * @return
     */
    public static String getRandom(int num) {
        double key = Math.random() * 100000;
        StringBuilder result = new StringBuilder(Integer.toString((int)key));
        if (result.length() > num) {
            result = new StringBuilder(result.substring(result.length() - num));
        } else {
            for (int i = num - result.length(); i > 0; i--) {
                result.insert(0, "0");
            }
        }
        return result.toString();
    }

    /**
     * 获取Md5码
     * 
     * @param key
     * @return String
     * @throws NoSuchAlgorithmException
     */
    public static String getEncode(String key) throws NoSuchAlgorithmException {
        MessageDigest messageDigest = MessageDigest.getInstance("MD5");
        messageDigest.update(key.getBytes(StandardCharsets.UTF_8));
        byte[] digest = messageDigest.digest();
        int j = digest.length;
        char[] str = new char[j * 2];
        int k = 0;
        for (byte byte0 : digest) {
            str[k++] = hexDigits[byte0 >>> 4 & 0xf];
            str[k++] = hexDigits[byte0 & 0xf];
        }

        return new String(str);
    }

    public static String getEncode(byte[] key) throws NoSuchAlgorithmException {
        MessageDigest messageDigest = MessageDigest.getInstance("MD5");
        messageDigest.update(key);
        byte[] digest = messageDigest.digest();
        int j = digest.length;
        char[] str = new char[j * 2];
        int k = 0;
        for (byte byte0 : digest) {
            str[k++] = hexDigits[byte0 >>> 4 & 0xf];
            str[k++] = hexDigits[byte0 & 0xf];
        }

        return new String(str);
    }

    static final char[] hexDigits = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};

}