1 【1】 计算文件MD5值的方法：
 2          /// <summary>
 3         /// 计算文件MD5值
 4         /// </summary>
 5         /// <param name="str">需要计算的文件路径</param>
 6         /// <returns>MD5值</returns>
 7         public static string MD5Value(String filepath)
 8         {
 9             MD5 md5 = new MD5CryptoServiceProvider();
10             byte[] md5ch;
11             using (FileStream fs = File.OpenRead(filepath))
12             {
13                 md5ch = md5.ComputeHash(fs);
14             }            
15             md5.Clear();
16             string strMd5 = "";
17             for (int i = 0; i < md5ch.Length - 1; i++)
18             {
19                 strMd5 += md5ch[i].ToString("x").PadLeft(2, ‘0‘);
20             }
21             return strMd5;
22         }

 1 //计算字符串的MD5
 2 public static string GetMD5(string sDataIn)
 3         {
 4             MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
 5             byte[] bytValue, bytHash;
 6             bytValue =http://www.mamicode.com/ System.Text.Encoding.UTF8.GetBytes(sDataIn);
 7             bytHash = md5.ComputeHash(bytValue);
 8             md5.Clear();
 9             string sTemp = "";
10             for (int i = 0; i < bytHash.Length; i++)
11             {
12                 sTemp += bytHash[i].ToString("X").PadLeft(2, ‘0‘);
13             }
14             return sTemp.ToLower();
15         }