Question

我正在尝试学习如何使用MailKit库，但我正在努力检索附件。到目前为止，我的代码将打开一个邮箱，浏览每个邮件并存储数据，如发件人，主题，正文，日期等，但我不能处理附件。

我试图在github和其他网站上使用其他人解决方案，但我仍然不明白他们在代码中做了什么，当我接近获得解决方案时，它会导致更多错误我感到压力并删除所有代码。我并不是说看起来很懒，但如果有人能解释我是如何做到的，我会很高兴。我基本上是在为Web表单应用程序构建一个邮件客户端。

下面是我的代码，所以你可以看到我相当无知:)

        // Open the Inbox folder
        client.Inbox.Open(FolderAccess.ReadOnly, cancel.Token);

        //get the full summary information to retrieve all details
        var summary = client.Inbox.Fetch(0, -1, MessageSummaryItems.Full, cancel.Token);
        foreach (var msg in summary)
        {
            //this code originally downloaded just the text from the body
            var text = msg.Body as BodyPartText;
            //but I tried altering it so that it will get attachments here also
            var attachments = msg.Body as BodyPartBasic;

            if (text == null)
            {
                var multipart = msg.Body as BodyPartMultipart;

                if (multipart != null)
                {
                    text = multipart.BodyParts.OfType<BodyPartText>().FirstOrDefault();
                }
            }

            if (text == null)
                continue;

            //I hoped this would get the messages where the content dispositon was not null
            //and let me do something like save the attachments somewhere but instead it throws exceptions
            //about the object reference not set to an instance of the object so it's very wrong
            if (attachments.ContentDisposition != null && attachments.ContentDisposition.IsAttachment)
            {
                //I tried to do the same as I did with the text here and grab the body part....... but no 
                var attachedpart = client.Inbox.GetBodyPart(msg.Index, attachments, cancel.Token);
            }

            else 
            {
                //there is no plan b :(
            }

            // this will download *just* the text 
            var part = client.Inbox.GetBodyPart(msg.Index, text, cancel.Token);
            //cast main body text to Text Part
            TextPart _body = (TextPart)part;

Answer 1

我不完全清楚你想要完成什么，但是如果你只是想下载消息附件（不下载整个消息）并将这些附件保存到文件系统，那么你可以通过以下方式实现这一点： / p>

var messages = client.Inbox.Fetch (0, -1, MessageSummaryItems.Full | MessageSummaryItems.UniqueId);
int unnamed = 0;

foreach (var message in messages) {
    var multipart = message.Body as BodyPartMultipart;
    var basic = message.Body as BodyPartBasic;

    if (multipart != null) {
        foreach (var attachment in multipart.BodyParts.OfType<BodyPartBasic> ().Where (x => x.IsAttachment)) {
            var mime = (MimePart) client.Inbox.GetBodyPart (message.UniqueId.Value, attachment);
            var fileName = mime.FileName;

            if (string.IsNullOrEmpty (fileName))
                fileName = string.Format ("unnamed-{0}", ++unnamed);

            using (var stream = File.Create (fileName))
                mime.ContentObject.DecodeTo (stream);
        }
    } else if (basic != null && basic.IsAttachment) {
        var mime = (MimePart) client.Inbox.GetBodyPart (message.UniqueId.Value, basic);
        var fileName = mime.FileName;

        if (string.IsNullOrEmpty (fileName))
            fileName = string.Format ("unnamed-{0}", ++unnamed);

        using (var stream = File.Create (fileName))
            mime.ContentObject.DecodeTo (stream);
    }
}

Answer 2

另一种适合我的选择，但似乎更简单：

var messages = client.Inbox.Fetch (0, -1, MessageSummaryItems.Full | MessageSummaryItems.BodyStructure | MessageSummaryItems.UniqueId);
int unnamed = 0;

foreach (var message in messages) {
    foreach (var attachment in message.Attachments) {
        var mime = (MimePart) client.Inbox.GetBodyPart (message.UniqueId.Value, attachment);
        var fileName = mime.FileName;

        if (string.IsNullOrEmpty (fileName))
            fileName = string.Format ("unnamed-{0}", ++unnamed);

        using (var stream = File.Create (fileName))
            mime.ContentObject.DecodeTo (stream);
    }
}

请注意，这是在Fetch语句中要求BODYSTRUCTURE而不是BODY，这似乎解决了附件未被标记的问题。

使用MailKit库保存附件？

2 个答案: