专家坐堂-[原创]发送邮件按钮代码问题，提示空值？Foxtable(狐表) - 新一代数据库软件，完美融合Access、Foxpro、Excel、vb.net之优势，人人都能掌握的快速软件开发工具!

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----  [原创]发送邮件按钮代码问题，提示空值？  (http://www.foxtable.com/bbs/dispbbs.asp?boardid=2&id=77862)

--  作者：fszyhzg
--  发布时间：2015/11/26 16:12:00
--  [原创]发送邮件按钮代码问题，提示空值？
狐友们，我设计了一个发送邮件窗口（如图）

此主题相关图片如下：qq图片20151126155203.png
窗口中的发送按钮代码如下：
Dim cb1 As String = e.Form.Controls("combobox1").value
Dim cb2 As String = e.Form.Controls("combobox2").value
Dim tb2 As String = e.Form.Controls("textbox2").value
Dim tb3 As String = e.Form.Controls("textbox3").value
Dim tb4 As String = e.Form.Controls("textbox4").value
Dim m As New MailSender
m.Host = "mail.btte.net"
m.Account = "fsxmtidc"
m.Password = "*******"
m.From = "fsxmtidc@btte.net"
m.To = cb1
m.To = cb2
m.Title = tb2
m.Content = tb3
m.AddAttachments(tb4)
m.SendAsync()
请问如何防止提示空值，例如抄送文本框为空就提示了或者附件为空也提示空值错误，请问如何解决？？

--  作者：大红袍
--  发布时间：2015/11/26 16:37:00
--
Dim cb1 As String = e.Form.Controls("combobox1").value
Dim cb2 As String = e.Form.Controls("combobox2").value
Dim tb2 As String = e.Form.Controls("textbox2").value
Dim tb3 As String = e.Form.Controls("textbox3").value
Dim tb4 As String = e.Form.Controls("textbox4").value
Dim m As New MailSender
m.Host = "mail.btte.net"
m.Account = "fsxmtidc"
m.Password = "*******"
m.From = "fsxmtidc@btte.net"
m.AddReceiver(cb1)
If cb2 > "" Then
    m.AddReceiver(cb2)
End If
m.Title = tb2
m.Content = tb3
If tb4 > "" Then
    m.AddAttachments(tb4)
End If
m.SendAsync()

--  作者：fszyhzg
--  发布时间：2015/11/26 17:09:00
--  回复：（大红袍）Dim cb1 As String = e.Form.Control...
袍哥，帮我看看这段代码，怎样才能把发邮件中的附件功能也添加进去，原代码是没有附件功能的
Dim dz As WinForm.TextBox = e.Form.Controls("TextBox1")
Dim dk As WinForm.TextBox = e.Form.Controls("TextBox2")
Dim zh As WinForm.TextBox = e.Form.Controls("TextBox3")
Dim mm As WinForm.TextBox = e.Form.Controls("TextBox4")
Dim fjr As WinForm.TextBox = e.Form.Controls("TextBox5")
Dim sj As WinForm.combobox = e.Form.Controls("combobox1")
Dim zt As WinForm.TextBox = e.Form.Controls("TextBox6")
Dim fj As WinForm.TextBox = e.Form.Controls("TextBox7")
Dim nr As WinForm.TextBox = e.Form.Controls("TextBox8")
Dim smtp As New System.Net.Mail.SmtpClient(dz.Text,dk.Text)
smtp.Credentials = New System.Net.NetworkCredential(zh.Text,mm.Text)
Dim mail As New System.Net.Mail.MailMessage()
mail.Subject = zt.Text
mail.SubjectEncoding = System.Text.Encoding.GetEncoding("GB2312")
mail.BodyEncoding = System.Text.Encoding.GetEncoding("GB2312")
mail.From = New System.Net.Mail.MailAddress(fjr.Text)
mail.Priority = System.Net.Mail.MailPriority.Normal
mail.IsBodyHtml = True
mail.Body = nr.Text
mail.To.Add(sj.Text)
Try
smtp.Send(mail)
MessageBox.Show("发送成功")
Catch
MessageBox.Show("发送失败")
Finally
mail.Dispose()
End Try

对应窗口（如图）
此主题相关图片如下：111.png

能否参考这些内容做修改？？
声明 Public ReadOnly Property Attachments As AttachmentCollection 用法 Dim instance As MailMessage Dim value As AttachmentCollection value = instance.Attachments

[此贴子已经被作者于2015/11/26 17:23:32编辑过]

--  作者：大红袍
--  发布时间：2015/11/26 17:31:00
--

附件的方式

http://www.foxtable.com/bbs/dispbbs.asp?BoardID=2&ID=74157&skin=0

--  作者：fszyhzg
--  发布时间：2015/11/27 9:35:00
--  回复：（大红袍）Dim cb1 As String = e.Form.Control...
袍哥，附件已经搞好了，但还有一个问题就是
If cb2 > "" Then
    m.AddReceiver(cb2)
End If
m.Title = tb2
m.Content = tb3
If tb4 > "" Then
    m.AddAttachments(tb4)
End If
这样写并不能取消如果附件或抄送或内容为空时会提示错误窗口的

此主题相关图片如下：1.png

--  作者：大红袍
--  发布时间：2015/11/27 9:48:00
--

Dim fj As WinForm.TextBox = e.Form.Controls("TextBox7")

If fj.Text > "" Then

    Dim attachment As new System.Net.Mail.Attachment(fj.Text, System.Net.Mime.MediaTypeNames.Application.Octet)
   message.Attachments.Add(attachment)

End If

--  作者：fszyhzg
--  发布时间：2015/11/27 10:18:00
--  回复：（大红袍）Dim fj As WinForm.TextBox = e.Form...
非常非常非常感谢袍哥，无法用言语表达对你的感激之情！袍哥万岁~~~