转载 URL短地址压缩算法

文章转载http://www.nowamagic.net/webdesign/webdesign_ShortUrlInTwitter.php

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/// <summary> /// 生成salt /// </summary> /// <returns></returns> public static string GenerateSalt() {     byte[] data = new byte[0x10];     new RNGCryptoServiceProvider().GetBytes(data);     return Convert.ToBase64String(data); }

　　

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public static string[] ShortUrl(string url)    {        //可以自定义生成MD5加密字符传前的混合KEY            string key = "anech";        //要使用生成URL的字符            string[] chars = new string[]{       "a" , "b" , "c" , "d" , "e" , "f" , "g" , "h" ,       "i" , "j" , "k" , "l" , "m" , "n" , "o" , "p" ,       "q" , "r" , "s" , "t" , "u" , "v" , "w" , "x" ,        "y" , "z" , "0" , "1" , "2" , "3" , "4" , "5" ,        "6" , "7" , "8" , "9" , "A" , "B" , "C" , "D" ,        "E" , "F" , "G" , "H" , "I" , "J" , "K" , "L" ,        "M" , "N" , "O" , "P" , "Q" , "R" , "S" , "T" ,        "U" , "V" , "W" , "X" , "Y" , "Z"     };          //对传入网址进行MD5加密            string hex = MD5(key + url);          string[] resUrl = new string[4];          for (int i = 0; i < 4; i++)        {            //把加密字符按照8位一组16进制与0x3FFFFFFF进行位与运算                int hexint = 0x3FFFFFFF & Convert.ToInt32("0x" + hex.Substring(i * 8, 8), 16);            string outChars = string.Empty;            for (int j = 0; j < 6; j++)            {                //把得到的值与0x0000003D进行位与运算，取得字符数组chars索引                    int index = 0x0000003D & hexint;                //把取得的字符相加                    outChars += chars[index];                //每次循环按位右移5位                    hexint = hexint >> 5;            }            //把字符串存入对应索引的输出数组                resUrl[i] = outChars;        }        return resUrl;    }      public static string MD5(String input)    {        byte[] res = new MD5CryptoServiceProvider().ComputeHash(Encoding.Default.GetBytes(input));        return BitConverter.ToString(res).Replace("-", "");    }