使用MimeKit从数据库读取时，电子邮件的丰富字符会被错误翻译
使用MimeKit从数据库读取时，电子邮件的丰富字符会被错误翻译
提问于 2019-04-24 21:59:45
我有一个用VB.Net编写的windows服务，它将电子邮件下载到MimeMessage对象中，删除其附件，然后将电子邮件的其余部分写入SQL Server数据库。一个单独的ASP.Net应用程序(使用VB.Net)将电子邮件读回到MimeMessage对象中，并根据请求将其返回给用户。
在此过程中发生了一些事情，导致在输出中出现奇怪的字符。
这个问题(Content encoding using MimeKit/MailKit)似乎很有希望，但将字符编码从ASCII码改为UTF8等并不能解决这个问题。
下面是将电子邮件保存到数据库的代码：
Sub ImportEmail(exConnectionString As String)
Dim oClient As New Pop3Client()
' … email connection code removed …
Dim message = oClient.GetMessage(0)
Dim strippedMessage As MimeMessage = message
' … code to remove attachments removed …
Dim mem As New MemoryStream
strippedMessage.WriteTo(mem)
Dim bytes = mem.ToArray
Dim con As New SqlConnection(exConnectionString)
con.Open()
Dim com As New SqlCommand("INSERT INTO Emails (Body) VALUES (@RawDocument)", con)
com.CommandType = CommandType.Text
com.Parameters.AddWithValue("@RawDocument", bytes)
com.ExecuteNonQuery()
con.Close()
End Sub下面是将其读回给用户的ASP.Net代码：
Private Sub OutputEmail(exConnectionString As String)
Dim BlobString As String = ""
Dim Sql As String = "SELECT Body FROM Emails WHERE Id = @id"
Dim com As New SqlClient.SqlCommand(Sql)
com.CommandType = CommandType.Text
com.Parameters.AddWithValue("@id", ViewState("email_id"))
Dim con As New SqlConnection(exConnectionString)
con.Open()
com.Connection = con
Dim da As New SqlClient.SqlDataAdapter(com)
Dim dt As New DataTable()
da.Fill(dt)
con.Close()
If dt.Rows.Count > 0 Then
Dim Row = dt.Rows(0)
BlobString = Row(0).ToString()
Dim MemStream As MemoryStream = GetMemoryStreamFromASCIIEncodedString(BlobString)
Dim message As MimeMessage = MimeMessage.Load(MemStream)
BodyBuilder.HtmlBody = message.HtmlBody
BodyBuilder.TextBody = message.TextBody
message.Body = BodyBuilder.ToMessageBody()
Response.ContentType = "message/rfc822"
Response.AddHeader("Content-Disposition", "attachment;filename=""" & Left(message.Subject, 35) & ".eml""")
Response.Write(message)
Response.End()
End If
End Sub
Private Function GetMemoryStreamFromASCIIEncodedString(ByVal BlobString As String) As MemoryStream
Dim BlobStream As Byte() = Encoding.ASCII.GetBytes(BlobString) ' **
Dim MemStream As MemoryStream = New MemoryStream()
MemStream.Write(BlobStream, 0, BlobStream.Length)
MemStream.Position = 0
Return MemStream
End Function例如，假设以下文本出现在原始电子邮件中：
“So long and thanks for all the fish” (fancy quotes)当回读时，它显示如下：
†So long and thanks for all the fishâ€其他字符替换如下：
-(长破折号)变成?欧元“
·(项目符号)变成·
回答 1
Stack Overflow用户
回答已采纳
发布于 2019-04-27 00:23:48
问题出在以下代码片段中：
If dt.Rows.Count > 0 Then
Dim Row = dt.Rows(0)
BlobString = Row(0).ToString() ' <-- the ToString() is the problem
Dim MemStream As MemoryStream = GetMemoryStreamFromASCIIEncodedString(BlobString)
Dim message As MimeMessage = MimeMessage.Load(MemStream)要修复数据损坏，您需要做的是：
If dt.Rows.Count > 0 Then
Dim Row = dt.Rows(0)
Dim BlobString as Byte() = Row(0)
Dim MemStream As MemoryStream = new MemoryStream (BlobString, False)
Dim message As MimeMessage = MimeMessage.Load(MemStream)你也可以摆脱你的GetMemoryStreamFromASCIIEncodedString函数。
(注意:我不知道VB.NET，所以我只是猜测语法，但它应该非常接近正确)
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/55831902
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