【发布时间】：2017-05-09 13:44:13
【问题描述】：
我指的是过去某处的上一篇文章（参见超链接）。我无法添加任何 cmets，也没有考虑写回复，因为我的问题略有不同。如果我在错误的版块中发帖或为此主题打开新帖子，请原谅，我还是这个论坛的新手。
请让我说明以下问题：与post 类似，我想从 MS Exchange Server 访问和检索电子邮件和附件。我主要使用了上面超链接中提供的代码，但是我无法连接到邮件服务器（我使用了587端口）。在我看来有一个成功的连接，但代码在到达以下行时停止
Dim Read_Stream2 = New StreamReader(Sstream)
表示无法读取数据流。
我也有关于这个特定行的问题，因为我无法弄清楚为什么需要将 NetworkStream 转换为 SslStream 然后转换为 StreamReader 对象。有人可以解释一下这种必要性吗？
至于剩下的问题，请考虑我到目前为止的代码。如果使用 IMAP 可能太麻烦，我也欢迎有关如何使用 POP3 实现此目标的提示。 预先感谢您提供的任何帮助。
Imports System.Net.Sockets
Imports System.IO
Imports System.Text
Imports System.Net.Security
Public Class emailDownloader
Dim ServerNm As String
Dim UsrNm As String
Dim PassStr As String
Dim _IntPort As Integer
Dim ImapClient As New Net.Sockets.TcpClient
Dim NetworkS_stream As NetworkStream
Dim m_sslStream As SslStream
Dim Read_Stream As StreamReader
Dim StatResp As String
Dim m_buffer() As Byte
Function Login(ByVal Sstream As SslStream, ByVal Server_Command As String)
ImapClient = New TcpClient(ServerNm, _IntPort)
NetworkS_stream = ImapClient.GetStream 'Read the stream
Sstream = New SslStream(NetworkS_stream)
Dim Read_Stream2 = New StreamReader(Sstream)
Server_Command = Server_Command ' + vbCrLf
m_buffer = System.Text.Encoding.ASCII.GetBytes(Server_Command.ToCharArray())
Sstream.Write(m_buffer, 0, m_buffer.Length)
Dim Server_Reponse As String
Server_Reponse = Read_Stream2.ReadLine()
Return Server_Reponse
End Function
Private Sub btnStart_Click(sender As System.Object, e As System.EventArgs) Handles btnStart.Click
lbMailsRetrieved.Items.Clear()
ServerNm = tbServerName.Text
_IntPort = tbPortName.Text
UsrNm = tbUserName.Text
PassStr = tbPasswort.Text
StatResp = Login(m_sslStream, "LOGIN " + UsrNm + " " + PassStr + " ") & vbCrLf
lbMailsRetrieved.Items.Add(StatResp)
End Sub
结束类
有一个最初用 C# 编写的解决方案，可以在 here 找到。我稍微修改了代码，它可以用于交换（仅此而已）。
Imports Microsoft.Exchange.WebServices.Data
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Linq
Imports System.Net.Sockets
Imports System.Text
Imports System.Threading.Tasks
Imports System.Windows.Forms
Namespace ReadMailFromExchangeServer
Public Class Form1
Inherits Form
Private exchange As ExchangeService
Public Sub New()
InitializeComponent()
lstMsg.Clear()
lstMsg.View = View.Details
lstMsg.Columns.Add("Date", 150)
lstMsg.Columns.Add("From", 250)
lstMsg.Columns.Add("Subject", 400)
lstMsg.Columns.Add("Has Attachment", 50)
lstMsg.Columns.Add("Id", 100)
lstMsg.FullRowSelect = True
End Sub
Private Sub btnRead_Click(sender As Object, e As EventArgs) Handles btnRead.Click
ConnectToExchangeServer()
'Dim ts As New TimeSpan(0, -1, 0, 0)
'Dim [date] As DateTime = DateTime.Now.Add(ts)
'Dim filter As New SearchFilter.IsGreaterThanOrEqualTo(ItemSchema.DateTimeReceived, [date])
If exchange IsNot Nothing Then
Dim findResults As FindItemsResults(Of Item) = exchange.FindItems(WellKnownFolderName.Inbox, New ItemView(50))
'Original
'Dim findResults As FindItemsResults(Of Item) = exchange.FindItems(WellKnownFolderName.Inbox, filter, New ItemView(50))
For Each item As Item In findResults
Dim message As EmailMessage = EmailMessage.Bind(exchange, item.Id)
Dim listItem As New ListViewItem({message.DateTimeReceived.ToString(), _
message.From.Name.ToString() + _
"(" + message.From.Address.ToString() + ")", _
message.Subject, (If((message.HasAttachments), "Yes", "No")), _
message.Id.ToString()})
lstMsg.Items.Add(listItem)
Next
If findResults.Items.Count <= 0 Then
lstMsg.Items.Add("No Messages found!!")
End If
End If
End Sub
Public Sub ConnectToExchangeServer()
lblMsg.Text = "Connecting to Exchange Server.."
lblMsg.Refresh()
Try
exchange = New ExchangeService(ExchangeVersion.Exchange2007_SP1)
exchange.Credentials = New WebCredentials("abc", "xyz")
exchange.AutodiscoverUrl("efg")
lblMsg.Text = "Connected to Exchange Server : " + exchange.Url.Host
lblMsg.Refresh()
Catch ex As Exception
lblMsg.Text = "Error Connecting to Exchange Server!!" + ex.Message
lblMsg.Refresh()
End Try
End Sub
Private Sub btnLoadAttachment_Click(sender As Object, e As EventArgs) Handles btnLoadAttachment.Click
If exchange IsNot Nothing Then
If lstMsg.Items.Count > 0 Then
Dim item As ListViewItem = lstMsg.SelectedItems(0)
If item IsNot Nothing Then
Dim msgid As String = item.SubItems(4).Text.ToString()
Dim message As EmailMessage = EmailMessage.Bind(exchange, New ItemId(msgid))
If message.HasAttachments AndAlso TypeOf message.Attachments(0) Is FileAttachment Then
Dim fileAttachment As FileAttachment = TryCast(message.Attachments(0), FileAttachment)
'Change the below Path
fileAttachment.Load("C:[my_path]" + fileAttachment.Name)
lblAttach.Text = "Attachment Downloaded : " + fileAttachment.Name
Else
MessageBox.Show("No Attachments found!!")
End If
Else
MessageBox.Show("Please select a Message!!")
End If
Else
MessageBox.Show("Messages not loaded!!")
End If
Else
MessageBox.Show("Not Connected to Mail Server!!")
End If
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs)
End Sub
Private Sub InitializeComponent()
Me.btnRead = New System.Windows.Forms.Button()
Me.lstMsg = New System.Windows.Forms.ListView()
Me.btnLoadAttachment = New System.Windows.Forms.Button()
Me.lblMsg = New System.Windows.Forms.Label()
Me.label1 = New System.Windows.Forms.Label()
Me.lblAttach = New System.Windows.Forms.Label()
Me.SuspendLayout()
'
'btnRead
'
Me.btnRead.BackgroundImageLayout = System.Windows.Forms.ImageLayout.None
Me.btnRead.FlatStyle = System.Windows.Forms.FlatStyle.Flat
Me.btnRead.Location = New System.Drawing.Point(39, 284)
Me.btnRead.Name = "btnRead"
Me.btnRead.Size = New System.Drawing.Size(174, 23)
Me.btnRead.TabIndex = 0
Me.btnRead.Text = "Read Mails"
Me.btnRead.UseVisualStyleBackColor = True
'
'lstMsg
'
Me.lstMsg.Location = New System.Drawing.Point(27, 70)
Me.lstMsg.Name = "lstMsg"
Me.lstMsg.Size = New System.Drawing.Size(664, 191)
Me.lstMsg.TabIndex = 1
Me.lstMsg.UseCompatibleStateImageBehavior = False
'
'btnLoadAttachment
'
Me.btnLoadAttachment.FlatStyle = System.Windows.Forms.FlatStyle.System
Me.btnLoadAttachment.Location = New System.Drawing.Point(517, 284)
Me.btnLoadAttachment.Name = "btnLoadAttachment"
Me.btnLoadAttachment.Size = New System.Drawing.Size(174, 23)
Me.btnLoadAttachment.TabIndex = 2
Me.btnLoadAttachment.Text = "Load Attachments"
Me.btnLoadAttachment.UseVisualStyleBackColor = True
'
'lblMsg
'
Me.lblMsg.AutoSize = True
Me.lblMsg.Location = New System.Drawing.Point(36, 361)
Me.lblMsg.Name = "lblMsg"
Me.lblMsg.Size = New System.Drawing.Size(38, 13)
Me.lblMsg.TabIndex = 3
Me.lblMsg.Text = "Ready"
'
'label1
'
Me.label1.AutoSize = True
Me.label1.Location = New System.Drawing.Point(24, 54)
Me.label1.Name = "label1"
Me.label1.Size = New System.Drawing.Size(82, 13)
Me.label1.TabIndex = 4
Me.label1.Text = "Today's Messages"
'
'lblAttach
'
Me.lblAttach.AutoSize = True
Me.lblAttach.Location = New System.Drawing.Point(514, 361)
Me.lblAttach.Name = "lblAttach"
Me.lblAttach.Size = New System.Drawing.Size(148, 13)
Me.lblAttach.TabIndex = 5
Me.lblAttach.Text = "No attachmment downloaded"
'
'Form1
'
Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
Me.ClientSize = New System.Drawing.Size(812, 591)
Me.Controls.Add(Me.lblAttach)
Me.Controls.Add(Me.label1)
Me.Controls.Add(Me.lblMsg)
Me.Controls.Add(Me.btnLoadAttachment)
Me.Controls.Add(Me.lstMsg)
Me.Controls.Add(Me.btnRead)
Me.Name = "Form1"
Me.Text = "Form1"
Me.ResumeLayout(False)
Me.PerformLayout()
End Sub
Friend WithEvents btnRead As System.Windows.Forms.Button
Friend WithEvents lstMsg As System.Windows.Forms.ListView
Friend WithEvents btnLoadAttachment As System.Windows.Forms.Button
Friend WithEvents lblMsg As System.Windows.Forms.Label
Friend WithEvents label1 As System.Windows.Forms.Label
Friend WithEvents lblAttach As System.Windows.Forms.Label
End Class
结束命名空间
【问题讨论】：
-
忘了说上面的代码没有使用 IMAP，但是它完成了工作。
标签： vb.net email network-programming protocols exchange-server