最近有同学问到如何计算一个字节数组的MD5值，现在分享一个扩展类，有了它，MD5计算再也不用其他了。

先看示例：

string s = "hello world";var s_md5= s.ToMD5();string f = @"C:\Windows\explorer.exe";var f_md5 = f.ToMD5File();byte[] b = System.IO.File.ReadAllBytes(f);var b_md5 = b.ToMD5();

   使用起来是不是很简单？下面是完整代码：

using System.IO;
using System.Security.Cryptography;
using System.Text;
namespace System
{/// <summary>/// MD5扩展类/// </summary>public static class MD5Extensions{/// <summary>/// 获取字符串的MD5值/// </summary>/// <param name="text">字符串</param>/// <param name="encode">编码，缺省UTF8</param>/// <returns>MD5 值</returns>public static string ToMD5(this string text, Encoding encode = null){if (encode == null) encode = Encoding.UTF8;MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();byte[] encryptedBytes = md5.ComputeHash(encode.GetBytes(text));return GetHashMD5(encryptedBytes);}/// <summary>/// 获取文件的MD5值/// </summary>/// <param name="path"></param>/// <returns></returns>public static string ToMD5File(this string path){try{using (Stream file = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read)){return file.ToMD5();}}catch (Exception e){return e.ToString();}}/// <summary>/// 获取流的MD5值/// </summary>/// <param name="s">流</param>/// <returns>MD5值</returns>public static string ToMD5(this Stream stream){byte[] hashbyte;using (MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider()){hashbyte = md5.ComputeHash(stream);}return GetHashMD5(hashbyte);}/// <summary>/// 获取字节数组的MD5值/// </summary>/// <param name="buffer">数组</param>/// <returns>MD5值</returns>public static string ToMD5(this byte[] buffer){byte[] hashbyte;using (MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider()){hashbyte = md5.ComputeHash(buffer, 0, buffer.Length);}return GetHashMD5(hashbyte);}/// <summary>/// Hash值转换MD5值格式/// </summary>/// <param name="hashbyte">Hash值</param>/// <returns>MD5值</returns>private static string GetHashMD5(byte[] hashbyte){string result = BitConverter.ToString(hashbyte);return result.Replace("-", "");}}
}

如果你比较懒，那么就nuget搜索MD5Extensions插入到项目中吧