StreamWriter不寫入文件

Question

我有一個方法，我發送文件作為附件。 我使用StreamWriter和MemoryStream來創建附件。 代碼如下：

public void ComposeEmail(string from, string to, SmtpClient client)
    {
        MailMessage mm = new MailMessage(from, to, "Otrzymałeś nowe zamówienie od "+from , "Przesyłam nowe zamówienie na sprzęt");
        mm.BodyEncoding = UTF8Encoding.UTF8;
        mm.DeliveryNotificationOptions = DeliveryNotificationOptions.OnFailure;
        // Adding attachment:

        using (var ms = new System.IO.MemoryStream())
        {
            using (var writer = new System.IO.StreamWriter(ms))
            {
                writer.Write("Hello its my sample file");
                writer.Flush();

                System.Net.Mime.ContentType ct = new System.Net.Mime.ContentType(System.Net.Mime.MediaTypeNames.Text.Plain);
                System.Net.Mail.Attachment attach = new System.Net.Mail.Attachment(ms, ct);
                attach.ContentDisposition.FileName = "myFile.txt";

                mm.Attachments.Add(attach);
                try
                {
                    client.Send(mm);
                }
                catch (SmtpException e)
                {
                    Console.WriteLine(e.ToString());
                }
            }
        }
    }

正如你可以在這些行中看到我寫的“文件”：

writer.Write("Hello its my sample file");
writer.Flush();

在調試時我可以看到MemoryStream長度為24（就像寫入字符串的長度一樣）。 但郵箱中收到的文件是空的。

我究竟做錯了什么？

Answer 1

嘗試重繞流：

writer.Flush();
ms.Position = 0; // <===== here

System.Net.Mime.ContentType ct = new System.Net.Mime.ContentType(
    System.Net.Mime.MediaTypeNames.Text.Plain);
System.Net.Mail.Attachment attach = new System.Net.Mail.Attachment(ms, ct);

否則，流仍然會定位在最后，從那里讀取將立即報告EOF。