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：

public class FileHelper
    {
        /// <summary>
        /// 对文件流进行MD5加密
        /// </summary>
        public static string MD5Stream(Stream stream)
        {
            MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
            md5.ComputeHash(stream);
            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"));
            }
            return sb.ToString();
        }
        /// <summary>
        /// 对文件进行MD5加密
        /// </summary>
        public static string MD5Stream(string filePath)
        {
            using (FileStream stream = File.Open(filePath, FileMode.Open))
            {
                return MD5Stream(stream);
            }
        }
    }