如何覆盖vb.net下载的文件

我正在制作一个自动文件下载程序，当我按下按钮时，我需要它来重新下载和覆盖文件

这是我的密码：

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
  My.Computer.Network.DownloadFile _
    ("http://www.randomurl.com/randomfile.txt", _
    Path.Combine(Environment.GetFolderPath( _
    Environment.SpecialFolder.ApplicationData), _
    "test/randomfile.txt"))
End Sub

存在允许覆盖上一个文件的重载

 My.Computer.Network.DownloadFile 
       (address, destinationFileName, userName,
        password, showUI, connectionTimeout, overwrite)

从MSDN开始

• 地址=字符串或Uri。要下载的文件的路径，包括 姓名和主机地址。必需的
• destinationFileName=字符串。下载文件的文件名和路径 文件必需的
• 用户名=字符串。要验证的用户名。默认值为空 字符串“”
• password=String。用于身份验证的密码。默认值为空字符串， “”
• showUI=Boolean。指定是否显示项目的进度 活动默认值为False
• connectionTimeout=Int32。超时间隔，以毫秒为单位。违约 是100秒
• 覆盖=布尔值。指定是否覆盖现有文件。 默认值为False

因此，您可以用这种方式更改代码

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
  My.Computer.Network.DownloadFile _
    (address := "http://www.randomurl.com/randomfile.txt", _
    destinationFileName := Path.Combine(Environment.GetFolderPath( _
    Environment.SpecialFolder.ApplicationData), _
    "test/randomfile.txt"), _
    userName := string.Empty, password := string.Empty, _
    showUI := False, connectionTimeout := 100000, _
    overwrite := True)
End Sub

（编辑-更改为按注释中的要求显示异步方法）

---

请注意，如果文件存在，它将被覆盖->

您的答案显然更好，因为它回答了原始问题。

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
    Dim uri As System.Uri = New System.Uri("http://www.randomurl.com/randomfile.txt")
    Dim webclient As System.Net.WebClient = New System.Net.WebClient()

    Dim path As String = New String(System.IO.Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "test\\randomfile.txt"))
    Dim fileInfo As System.IO.FileInfo = New System.IO.FileInfo(path)
    If Not System.IO.Directory.Exists(fileInfo.Directory.FullName) Then
        System.IO.Directory.CreateDirectory(fileInfo.Directory.FullName)
    End If

    AddHandler webclient.DownloadFileCompleted, AddressOf webclient_DownloadDataCompleted

    webclient.DownloadFileAsync(uri, path)

End Sub


Private Sub webclient_DownloadDataCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.AsyncCompletedEventArgs)

    MessageBox.Show("Your download has completed.")

End Sub