.NET 如何从电子邮件中提取嵌入的图像？

发布于 2024-08-01 16:46:45 字数 100 浏览 1 评论 0原文

您好，我正在开发 .NET 1.1 中的一个项目，我需要从我收到的电子邮件中提取（并将其保存在某处）嵌入图像。

有人可以告诉我从哪里开始吗？

谢谢

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谁对谁错谁最难过 2024-08-08 16:46:45

从 POP 服务器下载的电子邮件将是文本格式，您必须解析整个电子邮件，并找到所有具有 src 的标签属性设置为 cid:*

例如，

<img src='cid:006901c6d391$dee64770$6c822ecf@Z2LC74Q' />

包含嵌入图像的电子邮件的格式如下 -

From: foo1atbar.net 
To: foo2atbar.net 
Subject: A simple example 
Mime-Version: 1.0 
Content-Type: multipart/related; boundary="boundary-example"; type="text/html" 

--boundary-example 
Content-Type: text/html; charset="US-ASCII" 

... text of the HTML document, which might contain a URI 
referencing a resource in another body part, for example 
through a statement such as: 
<IMG SRC="cid:foo4atfoo1atbar.net" ALT="IETF logo"> 
...snip...
Content-Location: CID:somethingatelse ;this header is disregarded 
Content-ID: <006901c6d391$dee64770$6c822ecf@Z2LC74Q>
Content-Type: IMAGE/GIF 
Content-Transfer-Encoding: BASE64 

R0lGODlhGAGgAPEAAP/////ZRaCgoAAAACH+PUNv 
cHlyaWdodCAoQykgMTk5LiBVbmF1dGhvcml6ZWQgZHV 
wbGljYXRpb24gcHJvaGliaXRlZC4A etc... 

...snip...

如果您查看页脚，它包含图像的 BASE64 编码版本。您可以提取BASE64字符串，根据电子邮件字符集将其转换为字节，然后将其保存到文件中（您可以根据Content-Type获取文件扩展名）。田田，完成！

希望您知道如何去做！

编辑

我还发现了一个类似的问题此处。他正在使用 CDO（协作数据对象）。

The email downloaded from the POP server will be in text format, you will have to parse the whole email, and find all the <img /> tags having the src attribute set to cid:*

E.g.

<img src='cid:006901c6d391$dee64770$6c822ecf@Z2LC74Q' />

The format of an email containing the embedded image will be as follows -

From: foo1atbar.net 
To: foo2atbar.net 
Subject: A simple example 
Mime-Version: 1.0 
Content-Type: multipart/related; boundary="boundary-example"; type="text/html" 

--boundary-example 
Content-Type: text/html; charset="US-ASCII" 

... text of the HTML document, which might contain a URI 
referencing a resource in another body part, for example 
through a statement such as: 
<IMG SRC="cid:foo4atfoo1atbar.net" ALT="IETF logo"> 
...snip...
Content-Location: CID:somethingatelse ;this header is disregarded 
Content-ID: <006901c6d391$dee64770$6c822ecf@Z2LC74Q>
Content-Type: IMAGE/GIF 
Content-Transfer-Encoding: BASE64 

R0lGODlhGAGgAPEAAP/////ZRaCgoAAAACH+PUNv 
cHlyaWdodCAoQykgMTk5LiBVbmF1dGhvcml6ZWQgZHV 
wbGljYXRpb24gcHJvaGliaXRlZC4A etc... 

...snip...

If you take a look at the footer, it contains a BASE64 encoded version of your image. You can extract the the BASE64 string, convert it to bytes based on the email character set, and save it to a file (you can get the file extension based on the Content-Type). Tada, done!

Hope you've got an idea of how to do it!