package com.schisandra.system.common.utils;

import java.security.MessageDigest;

public class MD5Util {
    //十六进制下数字到字符的映射数组
    private final static String[] hexDigits = {"0", "1", "2", "3", "4",
            "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};


    /**
     * 把inputString加密
     */
    public static String md5(String inputString) {
        return encodeByMD5(inputString);
    }
    /**
     * 对字符串进行MD5加密
     */
    private static String encodeByMD5(String originString) {
        if (originString != null) {
            try {
                //创建具有指定算法名称的信息摘要
                MessageDigest md = MessageDigest.getInstance("MD5");
                //使用指定的字节数组对摘要进行最后更新，然后完成摘要计算
                byte[] results = md.digest(originString.getBytes("utf-8"));
                //将得到的字节数组变成字符串返回
                String resultString = byteArrayToHexString(results);
                return resultString.toUpperCase();
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
        return null;
    }
    /**
     * 转换字节数组为十六进制字符串
     *
     * @param
     * @return 十六进制字符串
     */
    private static String byteArrayToHexString(byte[] b) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));
        }
        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0) {
            n += 256;
        }
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

}

