c#-通过电子邮件发送带有长名称和重音的附件

发送包含包含长名和重音的附件的电子邮件时,我们遇到了问题.

大小或类型似乎不影响结果(我尝试使用txt& pdf,300kb和3833kb的大小)

经过一番搜索后,我发现此帖子http://social.msdn.microsoft.com/Forums/en-US/dotnetframeworkde/thread/b6c764f7-4697-4394-b45f-128a24306d55显示了如何解决该问题.

如果我的名字真的很长(请参阅attachment2变量名),它将起作用.
但是,如果名称略短(请参见附件1变量名称),则该名称显示为-= _ iso-8859-1_Q_Example,_Example_and_other_

我认为这与SplitEncodedAttachmentName中的以下行有关
            encodeAttachmentName = encodeAttachmentName.Remove(encodedAttachmentName.Length-encodingtoken.Length,encodingtoken.Length);

这是守望先锋的手表
attach1-“ =？ISO-8859-1？Q？Example = 2c_Example_and_other_Repr = e9senta.txt？=”

attach2-“ =？ISO-8859-1？Q？Example = 2c_Example_and_other_Repr = e9sentant_Example_Examp？==？ISO-8859-1？Q？le_Example_Example_Example_Example_Example2.txt？=”

我似乎无法正确发送附件1.

(我过去确实回答过这个问题-MailMessage Attachment filename with accents,但是我有一个错误,经过重构后遇到了这个问题.)

这是导致错误的最小代码示例.

class Program
{
    static void Main(string[] args)
    {
        Attachment attachment = new Attachment(@"c:\client\temp\Example,_Example_and_other_Représenta.pdf"); //3488kb
        Attachment attachment2 = new Attachment(@"c:\client\temp\Example,_Example_and_other_Représentant_Example_Example_Example_Example_Example_Example.pdf"); //3488kb

        Console.WriteLine(attachment.Name);

        MailMessage mm = new MailMessage();
         mm.From = new MailAddress("toemail");
         mm.To.Add("toemail");
        mm.Subject = "Yo";
        mm.Body = "hello";
        mm.Attachments.Add(CreateAttachment(attachment, attachment.Name)); // =_iso-8859-1_Q_Example,_Example_and_other_
        mm.Attachments.Add(CreateAttachment(attachment2, attachment2.Name));

        SmtpClient smtp = new SmtpClient("SmptServer");
        smtp.Send(mm);
    }

    /// <summary>
    /// This method fixes the name of the attachment to allow accents
    /// </summary>
    /// <remarks>Taken from http://social.msdn.microsoft.com/Forums/en-US/dotnetframeworkde/thread/b6c764f7-4697-4394-b45f-128a24306d55</remarks>
    public static Attachment CreateAttachment(Attachment attachmentFile, string displayName)
    {
        Attachment attachment = attachmentFile;
        attachment.TransferEncoding = TransferEncoding.Base64;

        string tranferEncodingMarker = "Q";
        string encodingMarker = "ISO-8859-1";
        int maxChunkLength = 76;

        attachment.NameEncoding = Encoding.GetEncoding(encodingMarker);

        string encodingtoken = String.Format("=?{0}?{1}?", encodingMarker, tranferEncodingMarker);
        string softbreak = "?=";
        string encodedAttachmentName = encodingtoken;
        encodedAttachmentName = HttpUtility.UrlEncode(displayName, Encoding.Default).Replace("+", " ").Replace("%", "=");

        encodedAttachmentName = SplitEncodedAttachmentName(encodingtoken, softbreak, maxChunkLength, encodedAttachmentName);
        attachment.Name = encodedAttachmentName;

        return attachment;
    }


    private static IEnumerable<string> SplitByLength(string stringToSplit, int length)
    {
        while (stringToSplit.Length > length)
        {
            yield return stringToSplit.Substring(0, length);
            stringToSplit = stringToSplit.Substring(length);
        }

        if (stringToSplit.Length > 0)
        {
            yield return stringToSplit;
        }
    }

    private static string SplitEncodedAttachmentName(string encodingtoken, string softbreak, int maxChunkLength, string encoded)
    {
        int splitLength = maxChunkLength - encodingtoken.Length - (softbreak.Length * 2);
        var parts = SplitByLength(encoded, splitLength);

        string encodedAttachmentName = encodingtoken;

        foreach (var part in parts)
        {
            encodedAttachmentName += part + softbreak + encodingtoken;
        }

        encodedAttachmentName = encodedAttachmentName.Remove(encodedAttachmentName.Length - encodingtoken.Length, encodingtoken.Length);

        return encodedAttachmentName;
    }
}

解决方法:

原来有错误报告-https://connect.microsoft.com/VisualStudio/feedback/details/696372/filename-encoding-error-when-encoding-utf-8-and-encoded-name-exceeds-the-length-of-a-single-mime-header-line#details

以及一篇kb的文章,以解决带有特殊字符的长名称的最初发行.
http://support.microsoft.com/kb/2402064

安装kb后,

我变了

mm.Attachments.Add(CreateAttachment(attachment,attachment.Name));
mm.Attachments.Add(CreateAttachment(attachment2,attachment2.Name));

回到应该是什么
mm.Attachments.Add(attachment);
mm.Attachments.Add(attachment2);

而且一切正常.

标签：email-attachments,encoding,email,diacritics,c
来源： https://codeday.me/bug/20191101/1982701.html