MD5编码

1   x2方式和x 方式的区别是 比如 比特为 0  x2显示的是 07 x显示的是 7 我们如果是要固定位32位MD5编码的话就使用x2方式

public static string GetMD5(string str) 
{ 
    StringBuilder sb = new StringBuilder(); 
    foreach (byte b in System.Security.Cryptography.MD5.Create().ComputeHash(Encoding.UTF8.GetBytes(str))) 
    { 
        sb.Append(b.ToString("x2")); 
    } 
    return sb.ToString(); 
}

2 对文件流进行MD5加密

/// <summary>
     /// 对文件流进行MD5加密
     /// </summary>
     /// <param name="filePath"></param>
     /// <returns></returns>
     /// <example></example>
     public static string MD5Stream(string filePath)
     {
         FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
       
         MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
         md5.ComputeHash(fs);
         fs.Close();
       
         byte[] b = md5.Hash;
         md5.Clear();
       
         StringBuilder sb = new StringBuilder(32);
         for (int i = 0; i < b.Length; i++)
         {
             sb.Append(b[i].ToString("X2"));
         }
       
         Console.WriteLine(sb.ToString());
         Console.ReadLine();
       
         return sb.ToString();
     }

3 对文件进行MD5加密

/// <summary>
      /// 对文件进行MD5加密
      /// </summary>
      /// <param name="filePath"></param>
      public static void MD5File(string filePath)
      {
          FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
          int bufferSize = 1048576; // 缓冲区大小，1MB
          byte[] buff = new byte[bufferSize];
      
          MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
          md5.Initialize();
      
          long offset = 0;
          while (offset < fs.Length)
          {
              long readSize = bufferSize;
              if (offset + readSize > fs.Length)
              {
                  readSize = fs.Length - offset;
              }
      
              fs.Read(buff, 0, Convert.ToInt32(readSize)); // 读取一段数据到缓冲区
      
              if (offset + readSize < fs.Length) // 不是最后一块
              {
                  md5.TransformBlock(buff, 0, Convert.ToInt32(readSize), buff, 0);
              }
              else // 最后一块
              {
                  md5.TransformFinalBlock(buff, 0, Convert.ToInt32(readSize));
              }
      
              offset += bufferSize;
          }
      
          fs.Close();
          byte[] result = md5.Hash;
          md5.Clear();
      
          StringBuilder sb = new StringBuilder(32);
          for (int i = 0; i < result.Length; i++)
          {
              sb.Append(result[i].ToString("X2"));
          }
      
          Console.WriteLine(sb.ToString());
          Console.ReadLine();
      }

4 返回指定文件的MD5值 

/// <summary>  
/// 返回指定文件的MD5值  
/// </summary>  
/// <param name="path"></param>  
/// <returns></returns>  
public static string Check(string path)
{
    if (!File.Exists(path))
        throw new ArgumentException(string.Format("<{0}>, 不存在", path));
    using (FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
    {
        MD5CryptoServiceProvider md5Provider = new MD5CryptoServiceProvider();
        byte[] buffer = md5Provider.ComputeHash(fs);
        string resule = BitConverter.ToString(buffer);
        resule = resule.Replace("-", "");
        return resule;
    }
}