package com.mall.util;

 import org.springframework.util.StringUtils;

 import java.security.MessageDigest;

 /**

  * Created by geely

  */

 public class MD5Util {

     /**

      * 将字节数组转为十六进制数

      * @param b

      * @return

      */

     private static String byteArrayToHexString(byte b[]) {

         StringBuffer resultSb = new StringBuffer();

         for (int i = 0; i < b.length; i++) {

             //每个字节转为十六进制数后进行拼接

             resultSb.append(byteToHexString(b[i]));

         }

         return resultSb.toString();

     }

     /**

      * 将某一个字节转为十六进制数

      * @param b

      * @return

      */

     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];

     }

     /**

      * 返回大写MD5

      *

      * @param origin 要加密的原字符串

      * @param charsetname 加密算法使用的字符集

      * @return

      */

     private static String MD5Encode(String origin, String charsetname) {

         String resultString = null;

         try {

             resultString = new String(origin);

             //初始化md5算法

             MessageDigest md = MessageDigest.getInstance("MD5");

             //md.digest(resultString.getBytes())获取数据的信息摘要，返回字节数组

             //byteArrayToHexString()将字节数组转为十六进制数

             if (charsetname == null || "".equals(charsetname)) {

                 //如果不传入字符集，则调用默认字符集

                 resultString = byteArrayToHexString(md.digest(resultString.getBytes()));

             }

             else {

                 resultString = byteArrayToHexString(md.digest(resultString.getBytes(charsetname)));

             }

         } catch (Exception exception) {

         }

         return resultString.toUpperCase();

     }

     /**

      * 唯一public方法对外公开

      * @param origin

      * @return

      */

     public static String MD5EncodeUtf8(String origin) {

         //对原字符串加盐值返回

         origin = origin + PropertiesUtil.getProperty("password.salt", "");

         //传入utf-8字符集

         return MD5Encode(origin, "utf-8");

     }

     //十六进制数组值

     private static final String hexDigits[] = {"0", "1", "2", "3", "4", "5",

             "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};

 }