获取文件的MD5码（C#）

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;namespace Test
{
public class MD5Code
{
/// <summary>
/// 获取文件的MD5码
/// </summary>
/// <param name="fileName">传入的文件名（含路径及后缀名）</param>
/// <returns></returns>
public string GetMD5HashFromFile(string fileName)
{
try
{
FileStream file = new FileStream(fileName, System.IO.FileMode.Open);
MD5 md5 = new MD5CryptoServiceProvider();
byte[] retVal = md5.ComputeHash(file);
file.Close();
StringBuilder sb = new StringBuilder();
for (int i = ; i < retVal.Length; i++)
{
sb.Append(retVal[i].ToString("x2"));
}
return sb.ToString();
}
catch (Exception ex)
{
throw new Exception("GetMD5HashFromFile() fail,error:" + ex.Message);
}
}
}
}