来自MemoryStream的电子邮件附件是空的 [英] email attachment from the MemoryStream comes empty

问题描述

_data是附件数据的byte []数组。

_data is a byte[] array of Attachment data.

当我这样做：

 var ms = new MemoryStream(_data.Length); 
 ms.Write(_data,0,_data.Length);
 mailMessage.Attachments.Add(new Attachment(ms, attachment.Name));

附件为空。实际上outlook显示文件大小，但它是不正确的。

Attachment comes empty. Actually outlook shows the filesize but it's incorrect.

嗯，我以为在_data有一个问题。然后我决定尝试这种方法：

Well, I thought there is a problem in my _data. Then I decided to try this approach:

 var ms = new MemoryStream(_data.Length); 
 ms.Write(_data,0,_data.Length);
 fs = new FileStream(@"c:\Temp\"+attachment.Name,FileMode.CreateNew);
 fs.Write(ms.GetBuffer(), 0, ms.GetBuffer().Length);
 fs.Flush();
 fs.Close();
 mailMessage.Attachments.Add(new Attachment(@"c:\Temp\" + attachment.Name));

这有效。第一个问题是什么？

And that works. What's wrong with the first one?

推荐答案

使用第一个表单，您不会倒带流：

With the first form, you're not "rewinding" the stream:

ms.Position = 0;

所以尝试从流的结尾读取没有任何数据。

So it was trying to read from the end of the stream, where there wasn't any data.

创建MemoryStream的一种更简单的方法是仅使用构造函数：

A simpler way of creating the MemoryStream is to just use the constructor though:

var ms = new MemoryStream(_data);
mailMessage.Attachments.Add(new Attachment(ms, attachment.Name));

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