MD5文件校验

public static string GetFileMd5Hash(string strFileFullPath)
{
    // Create a new instance of the MD5CryptoServiceProvider object.
    System.IO.FileStream fst = null;
    try
    {
        fst = new System.IO.FileStream(strFileFullPath, System.IO.FileMode.Open);
        System.Security.Cryptography.MD5 md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
        // Convert the input string to a byte array and compute the hash.
        byte[] data =md5 .ComputeHash(fst);
        // Create a new Stringbuilder to collect the bytes
        // and create a string.
        StringBuilder sBuilder = new StringBuilder();
        // Loop through each byte of the hashed data 
        // and format each one as a hexadecimal string.
        for (int i = 0; i < data.Length; i++)
        {
            sBuilder.Append(data[i].ToString("x2"));
        }
        fst.Close();
        // Return the hexadecimal string.
        return sBuilder.ToString().ToLower();
    }
    catch (System.Exception ex)
    {
        if (fst != null)
            fst.Close();
        return "";
    }
    finally
    {
    }
}