C# 二进制转base64

public static string ConvertUploadFileToBase64(HttpPostedFileBase file)
        {
            using (MemoryStream memoryStream = new MemoryStream())
            {
                file.InputStream.CopyTo(memoryStream);
                byte[] binaryData = memoryStream.ToArray();
                string base64String = Convert.ToBase64String(binaryData);
                return base64String;
            }
        }

var base64Str =Tool.ConvertUploadFileToBase64(Request.Files.Get(0));