C# 计算文件MD5

因工作需要对文件进行是否被修改判断，整理的一段生成文件MD5码的代码：

   1:  public class FileHelper

   2:      {

   3:          /// <summary>

   4:          /// 对文件流进行MD5加密

   5:          /// </summary>

   6:          public static string MD5Stream(Stream stream)

   7:          {

   8:              MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();

   9:              md5.ComputeHash(stream); 

  10:              byte[] b = md5.Hash;

  11:              md5.Clear();

  12:              StringBuilder sb = new StringBuilder(32);

  13:              for (int i = 0; i < b.Length; i++)

  14:              {

  15:                  sb.Append(b[i].ToString("X2"));

  16:              }

  17:              return sb.ToString();

  18:          }

  19:          /// <summary>

  20:          /// 对文件进行MD5加密

  21:          /// </summary>

  22:          public static string MD5Stream(string filePath)

  23:          {

  24:              using (FileStream stream = File.Open(filePath, FileMode.Open))

  25:              {

  26:                  return MD5Stream(stream); 

  27:              }

  28:          }

  29:      }

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