尝试将System.IO.MemoryStreamEmailAttachment附加到EmailMessage时，抛出带有消息Cannot access a closed Stream的错误System.ObjectDisposedException。附件是使用 HtmlRenderer.PdfSharp 生成的。附加和发送是在 using 语句中完成的。
using (MemoryStream ms = new MemoryStream())
{
var pdf = PdfGenerator.GeneratePdf("<html><body>foo</body></html>", PdfSharp.PageSize.Letter);
// 2nd argument is to NOT close stream
pdf.Save(ms, false);
EmailMessage em = new EmailMessage();
em.EmailFormat = EmailFormatEnum.Html;
em.From = "no-reply@foo.com";
em.Recipients = "foo.bar@baz.net";
em.Subject = "Attachment Name";
em.Body = "There is an attachment";
var attachment = new EmailAttachment(ms, "foo.pdf");
em.Attachments.Add(attachment);
// SiteContext.CurrentSiteName argument is just a site name required for Kentico CMS
// true argument is send immediately
EmailSender.SendEmail(SiteContext.CurrentSiteName, em, true);
}
如果我改为执行以下操作，则只要我不尝试在try块内ms.Dispose()，错误就不会发生：
MemoryStream ms = new MemoryStream();
try
{
var pdf = PdfGenerator.GeneratePdf(html, PdfSharp.PageSize.A4);
pdf.Save(ms, false);
EmailMessage em = new EmailMessage();
em.EmailFormat = EmailFormatEnum.Html;
em.From = "no-reply@foo.com";
em.Recipients = "foo.bar@baz.net";
em.Subject = "Attachment Name";
em.Body = "There is an attachment";
var attachment = new EmailAttachment(ms, "foo.pdf");
em.Attachments.Add(attachment);
EmailSender.SendEmail(SiteContext.CurrentSiteName, em, true);
}
catch (Exception)
{
ms.Dispose();
}
第二种方法的问题是MemoryStream没有被显式处置。MemoryStream是否天生就被采用这种方法？如果放在整个块之后ms.Dispose();，则会发生相同的Cannot access a closed Stream。这是等待发生的内存泄漏吗？如何在不关闭流以允许电子邮件发送附件的情况下处置MemoryStream？
这是需要以某种方式等待SendEmail()实际执行其功能的问题吗？
感谢您提供的任何帮助。
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我不明白你为什么要在try块中处理ms，通常是为了清理变量，你使用finally 块，无论是否有异常，它都会被执行。
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如果您使用 catch(那种带有 Exception 的捕获会捕获所有异常(，则不会收到错误，因为您正在捕获它们
你应该怎么做是：
MemoryStream ms = new MemoryStream();
try
{
var pdf = PdfGenerator.GeneratePdf(html, PdfSharp.PageSize.A4);
pdf.Save(ms, false);
EmailMessage em = new EmailMessage();
em.EmailFormat = EmailFormatEnum.Html;
em.From = "no-reply@foo.com";
em.Recipients = "foo.bar@baz.net";
em.Subject = "Attachment Name";
em.Body = "There is an attachment";
var attachment = new EmailAttachment(ms, "foo.pdf");
em.Attachments.Add(attachment);
EmailSender.SendEmail(SiteContext.CurrentSiteName, em, true);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
finally
{
ms.Dispose();
}
我能够使用以下代码找到解决方案。关于SendMail()论点，sendImmediately这实际上可能更像是肯蒂科CMS的问题。通过将其设置为false(默认值(，我能够将流附加为EmailAttachment，而不会using语句中出现System.ObjectDisposedException错误。
using (MemoryStream ms = new MemoryStream())
{
var pdf = PdfGenerator.GeneratePdf(html, PdfSharp.PageSize.Letter);
pdf.Save(ms, false);
EmailMessage em = new EmailMessage();
em.EmailFormat = EmailFormatEnum.Html;
em.From = "no-reply@foo.com";
em.Recipients = "foo.bar@baz.net";
em.Subject = "Attachment Name";
em.Body = "There is an attachment.";
var attachment = new EmailAttachment(ms, "foo.pdf");
em.Attachments.Add(attachment);
// default sendImmediately of false
EmailSender.SendEmail(SiteContext.CurrentSiteName, em);
}
好吧，您只需要在从 Kentico 访问之前关闭流，即：
using (MemoryStream ms = new MemoryStream())
{
var pdf = PdfGenerator.GeneratePdf(html, PdfSharp.PageSize.Letter);
pdf.Save(ms, false);
}
然后你做你的电子邮件部分：
EmailMessage em = new EmailMessage();
em.EmailFormat = EmailFormatEnum.Html;
em.From = "no-reply@foo.com";
em.Recipients = "foo.bar@baz.net";
em.Subject = "Attachment Name";
em.Body = "There is an attachment.";
using (MemoryStream ms = new MemoryStream())
{
var attachment = new EmailAttachment(ms, "foo.pdf");
em.Attachments.Add(attachment);
}
EmailSender.SendEmail(SiteContext.CurrentSiteName, em);