.net 使用WebClient登录和下载文件

我已经找到了很多这样做的例子，但是没有任何一种组合能够起作用

基本上，我有一个内联网系统，可以从web链接生成文档，我知道要下载哪些文档。我能够生成要下载的链接列表，但在程序内对系统进行身份验证时遇到问题。我一直收到一个401错误：

Public Shared Sub DownloadFiles(_tool As Tool)
    Dim links As List(Of String) = GetJiraLinks(_tool)

    Dim downloader As New WebClient

    ' Initialize the client
    Dim reqParm As New Specialized.NameValueCollection

    reqParm.Add("os_username", "user")
    reqParm.Add("os_password", "pass")
    reqParm.Add("os_destination", "/secure/")

    downloader.Credentials = New NetworkCredential("user", "pass")

    Dim uploadLocation As String = My.Settings.jiraLocation & "login.jsp"

    'downloader.Headers.Add("Content-Type", "application/x-www-form-urlencoded")

    Dim responseBytes = downloader.UploadValues(uploadLocation, "POST", reqParm)

    Dim responseBody = (New Text.UTF8Encoding).GetString(responseBytes)

    Dim workingDir As String = CreateWorkingDir()

    For Each link As String In links
        Dim tempUri As New Uri(link)

        Dim localpath As String = workingDir & "\" & System.IO.Path.GetFileName(tempUri.LocalPath)

        downloader.DownloadFile(tempUri, localpath)
    Next
End Sub

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我想我会发布一个完整的解决方案示例。许多其他帖子链接到一个支持cookie的web客户端（），但没有在实际操作中显示它。这是我的：

Public Shared Sub DownloadFiles(_tool As Tool)
    Dim links As List(Of String) = GetJiraLinks(_tool)

    Dim downloader As New CookieAwareWebClient

    ' Start by requesting the page.

    Dim loginPage As String = My.Settings.jiraLocation & "login.jsp"

    ' Initialize the client
    Dim reqParm As New Specialized.NameValueCollection

    reqParm.Add("os_username", "user")
    reqParm.Add("os_password", "pass")
    reqParm.Add("os_destination", "/secure/")

    Dim responseBytes = downloader.UploadValues(loginPage, "POST", reqParm)

    Dim responseBody = (New Text.UTF8Encoding).GetString(responseBytes)

    Dim workingDir As String = CreateWorkingDir()

    For Each link As String In links
        Dim tempUri As New Uri(link)

        Dim localpath As String = workingDir & "\" & System.IO.Path.GetFileName(tempUri.LocalPath)

        downloader.DownloadFile(tempUri, localpath)
    Next
End Sub

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你以前看过发生了什么吗？谢谢你。使用这个，我可以看到有一个曲奇不知何故涉及。我猜WebClient没有保存此cookie。我找到了，但它没有显示如何使用它。