从 FTP 下载的图像文件，大小为 0 字节

Question

我发现这段代码可以从 FTP 中的目录和子目录下载图像文件：
.

所以这是我在 VB.NET 中的代码：

Private Sub DownloadFtpDirectory(ByVal url As String, ByVal credentials As NetworkCredential, ByVal localPath As String)
    Dim listRequest As FtpWebRequest = CType(WebRequest.Create(url), FtpWebRequest)
    listRequest.Method = WebRequestMethods.Ftp.ListDirectoryDetails
    listRequest.Credentials = credentials
    Dim lines As List(Of String) = New List(Of String)
    Dim listResponse As FtpWebResponse = CType(listRequest.GetResponse, FtpWebResponse)
    Dim listStream As Stream = listResponse.GetResponseStream
    Dim listReader As StreamReader = New StreamReader(listStream)

    While Not listReader.EndOfStream
        lines.Add(listReader.ReadLine)

    End While

    For Each line As String In lines
        Dim tokens As String() = line.Split({" "}, 9, StringSplitOptions.RemoveEmptyEntries)
        Dim name As String = tokens(8)
        Dim permissions As String = tokens(0)
        Dim localFilePath As String = Path.Combine(localPath, name)
        Dim fileUrl As String = (url + name)
        If (permissions(0) = ChrW(100)) Then
            If Not Directory.Exists(localFilePath) Then
                Directory.CreateDirectory(localFilePath)
            End If

            DownloadFtpDirectory((fileUrl + "/"), credentials, localFilePath)
        Else
            Dim downloadRequest As FtpWebRequest = CType(WebRequest.Create(fileUrl), FtpWebRequest)
            downloadRequest.Credentials = credentials
            downloadRequest.KeepAlive = False
            downloadRequest.Method = WebRequestMethods.Ftp.DownloadFile
            downloadRequest.UseBinary = True
            downloadRequest.Proxy = Nothing
            downloadRequest.UsePassive = False

            Dim downloadResponse As FtpWebResponse = CType(downloadRequest.GetResponse, FtpWebResponse)
            Dim sourceStream As Stream = downloadResponse.GetResponseStream
            Dim targetStream As FileStream = New FileStream(localFilePath, FileMode.Create)

            Dim buffer() As Byte = New Byte((10240) - 1) {}
            Dim read As Integer

            While (sourceStream.Read(buffer, 0, buffer.Length) > 0)
                targetStream.Write(buffer, 0, read)

            End While

        End If

    Next
End Sub

然后我通过这个方法调用函数：

Private Sub btnDownloadImagesFromFTP_Click(sender As Object, e As EventArgs) Handles btnDownloadImagesFromFTP.Click
    Try             
        Dim credentials As NetworkCredential = New NetworkCredential("user", "password")
        Dim url As String = "ftp://myftp/imagesDirectory/"
        DownloadFtpDirectory(url, credentials, "C:\Users\Admin\Desktop\imagesFromFTP")
    Catch ex As Exception
        MessageBox.Show(ex.Message.ToString)
    End Try
End Sub

代码工作正常并下载包含图像文件和名称的子目录，但是当我打开任何图像时，它是空的（0 字节）

有人知道为什么会这样吗？谢谢

Answer 1

您从未分配 read 变量。

While ((read = sourceStream.Read(buffer, 0, buffer.Length)) > 0)

从 FTP 下载的图像文件，大小为 0 字节

Image files download from FTP with 0 bytes

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