如何暂停将文件上传到 .Net 中的 Dropbox

Question

我在 Windows 10 32 位上使用 VB.Net 和 .NET Framework 4.6.2，我的文件几乎是 12mb。

我使用此代码将文件上传到 Dropbox。

Public Async Function ChunkUpload(ByVal ThisFilePath As String, Progress1 As ToolStripProgressBar,
                                      Optional folder As String = ("/Tests")) As Task
        Dim config = New DropboxClientConfig("Project.vb")
        Dim client = New DropboxClient(My.Settings.AccessToken, config)
        Const chunkSize As Integer = 1024 * 1024
        Dim LocalFileName As String = ThisFilePath.Remove(0, ThisFilePath.LastIndexOf("\") + 1)
        Dim fs As IO.FileStream = New IO.FileStream(ThisFilePath, IO.FileMode.Open)
        Dim data As Byte() = New Byte(fs.Length) {}
        fs.Read(data, 0, data.Length)
        fs.Close()
        Try
            Using thisstream = New IO.MemoryStream(data)
                Dim numChunks As Integer = CType(Math.Ceiling((CType(thisstream.Length, Double) / chunkSize)), Integer)
                Dim buffer() As Byte = New Byte((chunkSize) - 1) {}
                Dim sessionId As String = Nothing
                Dim idx = 0
                Do While idx < numChunks
                    Dim byteRead = thisstream.Read(buffer, 0, chunkSize)
                    Dim memStream As IO.MemoryStream = New IO.MemoryStream(buffer, 0, byteRead)
                    If idx = 0 Then
                        Dim result = Await client.Files.UploadSessionStartAsync(body:=memStream)
                        sessionId = result.SessionId
                    Else
                        Dim cursor As Files.UploadSessionCursor = New Files.UploadSessionCursor(sessionId, CType((chunkSize * idx), ULong))
                        If idx = numChunks - 1 Then
                            'Overwrite, if existed
                            Await client.Files.UploadSessionFinishAsync(cursor,
                                                                        New Files.CommitInfo(
                                                                        (folder + ("/" + ThisFilePath)),
                                                                        Files.WriteMode.Overwrite.Instance, False, Nothing, False), memStream)
                        Else
                            Await client.Files.UploadSessionAppendV2Async(cursor, body:=memStream)
                        End If
                    End If
                    idx += 1
                    Application.DoEvents()
                    Progress1.Value = CInt((idx / numChunks) * 100)
                    Progress1.ToolTipText = Progress1.Value & "%"
                Loop
                If Progress1.Value = 100 Then
                    Progress1.Value = 0
                    Progress1.ToolTipText = Progress1.Value & "%"
                End If
            End Using
        Catch ex As DropboxException
            MsgBox(ex.Message)
        End Try
    End Function

我已经有另一个功能 returns Access-Token 并将其存储在 My.Settings.AccessToken 中。在我的表单中，我调用此函数来上传文件：

Private Async Sub DropboxToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles DropboxToolStripMenuItem.Click
        Dim DropThis As New Drobbox
        Dim NewBakFile As String = "MYFILE.EXT" & Now.Date.ToShortDateString
        Try
            If ToolStripProgressBar1.Value <> 100 Then
                Try
                    IO.File.Copy("ThisDB.accdb", NewBakFile, True)
                Catch ex As IO.IOException
                    MsgBox("Error Copy : " & ex.Message)
                End Try
                ToolStripProgressBar1.Visible = True
                BackupToolStripMenuItem.Enabled = False
                'I obtain and store Access-Token here.
                Await DropThis.ChunkUpload(NewBakFile, ToolStripProgressBar1)
                BackupToolStripMenuItem.Enabled = True
                ToolStripProgressBar1.Visible = False
                DropLblUid.Text = ("Uploaded successfully. (" & Now.ToString("hh:mm:ss tt") & ")")
                Try
                    IO.File.Delete(NewBakFile)
                Catch ex As IO.IOException
                    MsgBox("Delete Error : " & ex.Message)
                End Try
            End If
        Catch ex As IO.IOException
            MsgBox(ex.Message)
        Finally
            DropboxToolStripMenuItem.Enabled = True
        End Try
    End Sub

我的问题是：如何Pause/Resume/Stop上传文件？

更新(1) : 我找到了这个article关于Upload/Cancel/Pause，我去看看..... 那个方法没有帮助

更新 (2)：我正在尝试按照@Greg 的建议想出一个解决方法。

Answer 1

Dropbox API "upload session" 功能是一种通过分段上传大文件的方式。该应用程序通过最初调用 UploadSessionStartAsync 为需要上传的每个大文件创建一个 "upload session"。每个上传会话的有效期为 48 小时。

对UploadSessionStartAsync、UploadSessionAppendV2Async、UploadSessionFinishAsync的每次调用都可以包含一个连续的片段的文件。

如果您希望暂停上传会话，您可以通过在对这三种方法中的任何一种的调用之间插入您想要的任何流量控制来实现。只要您随后使用相同的 cursor 继续运行代码，在 48 小时内，您就可以继续并完成上传会话。

如何暂停将文件上传到 .Net 中的 Dropbox

How can I pause uploading File to Dropbox in .Net

vb.net

file-upload

dropbox-api

pause