将普通电子邮件转换为嵌入式资源电子邮件

引言

大家好，这是我的第一篇文章 ^^。我编写了这个小函数，它在工作中帮助了我，我想分享它。这个想法是将普通的 HTML 输入转换为一个函数，该函数将返回一个 AlternateView 对象，该对象可用于使用 VB/ASP.NET 邮件对象发送电子邮件。

嗯，这个函数**完全**没有经过优化，并且使用了一些正则表达式。顺便说一下，我对正则表达式也很陌生，因此，如果需要任何更改/优化，请告诉我。

Using the Code

这是一个简单的函数，它查找所有图像/CSS/JS（查找 URL、src 标签）资源并将它们链接到电子邮件。

这是代码

Public Function convertToEmbedResource(ByVal emailHtml$) As AlternateView

    'This is the website where the resources are located
    Dim webSiteUrl$ = "http://www.thewebsite.com/myresources/"
    
    ' The first regex finds all the url/src tags.
    Dim matchesCol As MatchCollection = Regex.Matches(emailHtml, _
                   "url\(['|\""]+.*['|\""]\)|src=[""|'][^""']+[""|']")

    Dim normalRes As Match

    ' I didnt knew how to declare a new LinkedResourceCol so i did this :
    Dim resCol As AlternateView = _
        AlternateView.CreateAlternateViewFromString("", _
        Nothing, "text/html")
    Dim resId% = 0
    
    ' Between the findings
    For Each normalRes In matchesCol
    
        Dim resPath$
    
        ' Replace it for the new content ID that will be embeded
        If Left(normalRes.Value, 3) = "url" Then
            emailHtml = emailHtml.Replace(normalRes.Value, _
                 "url(cid:EmbedRes_" & resId & ")")
        Else
            emailHtml = emailHtml.Replace(normalRes.Value, _
                 "src=""cid:EmbedRes_" & resId & """")
        End If
        
        ' Clean the path

        resPath = Regex.Replace(normalRes.Value, "url\(['|\""]", "")
        resPath = Regex.Replace(resPath, "src=['|\""]", "")

        resPath = Regex.Replace(resPath, "['|\""]\)", _
                  "").Replace(webSiteUrl, "").Replace("""", "")

        
        ' Map it on the server
        resPath = Server.MapPath(resPath)

        
        ' Embed the resource
        Dim theResource As LinkedResource = New LinkedResource(resPath)
        theResource.ContentId = "EmbedRes_" & resId
        resCol.LinkedResources.Add(theResource)
        
        ' Next resource ID
        resId = resId + 1

    Next
    
    ' Create our final object
    Dim finalEmail As AlternateView = _
        Net.Mail.AlternateView.CreateAlternateViewFromString(emailHtml, _
        Nothing, "text/html")
    Dim transferResource As LinkedResource

    ' And transfer all the added resources to the output object
    For Each transferResource In resCol.LinkedResources
        finalEmail.LinkedResources.Add(transferResource)
    Next    
    
    return finalEmail

End Function

发送电子邮件

这是发送电子邮件的代码

Dim mail As New MailMessage()
mail.From = New MailAddress("me@me.com")
mail.To.Add("me@me.com")
mail.Subject = " Embed Resources "

mail.AlternateViews.Add(convertToEmbedResource(" MY HTML EMAIL "))
Dim smtp As New SmtpClient("127.0.0.1")
smtp.Send(mail)