MD5方法

 

　　

//计算MD5值的方法 不可逆性
/// <summary>
/// 计算单个字符的MD5方法
/// </summary>
/// <param name="str"></param>
/// <returns></returns>
/// this是扩展的方法 必须定义在static类中

   public static string CalcMD5(this string str) {
            byte[] bytes = System.Text.Encoding.UTF8.GetBytes(str);
            return CalcMD5(bytes);

/// <summary>
/// 计算byte数组的MD5方法
/// </summary>
/// <param name="bytes"></param>
/// <returns></returns>

private static string CalcMD5(byte[] bytes)
        {
            using (MD5 md5 = MD5.Create())
            {
                byte[] computeBytes = md5.ComputeHash(bytes);
                string result = "";
                for (int i = 0; i < computeBytes.Length; i++)
                {
                    result += computeBytes[i].ToString("X").Length == 1 ? "0" + computeBytes[i].ToString("X") : computeBytes[i].ToString("X");
                }
                return result;
            }
        }

/// <summary>
///计算 Stream流的MD5方法
/// </summary>
/// <param name="stream"></param>
/// <returns></returns>

 private static string CalcMD5(Stream stream )
        {
            using (MD5 md5 = MD5.Create())
            {
                byte[] computeBytes = md5.ComputeHash(stream);
                string result = "";
                for (int i = 0; i < computeBytes.Length; i++)
                {
                    result += computeBytes[i].ToString("X").Length == 1 ? "0" + computeBytes[i].ToString("X") : computeBytes[i].ToString("X");
                }
                return result;
            }
        }