如何添加DownloadFileAsync到更新程序在vb.net

Question

我正在做一个自动文件下载器，我需要它重新下载和覆盖文件，当我按下按钮，但我不希望它挂在它时正在下载。 我不知道如何实现DownloadFileAsync这个代码。请帮忙！

这里是我的代码：

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click 
     Button1.Enabled = False 
     Button1.Text = "Updating..." 
     WebBrowser1.Visible = True 
     My.Computer.Network.DownloadFile _ 
      (address:="http://199.91.154.170/e9f6poiwfocg/pei02c8727sa720/Ultra+v08.zip", _ 
      destinationFileName:=Path.Combine(Environment.GetFolderPath(_ 
      Environment.SpecialFolder.ApplicationData), _ 
      "test/Test.zip"), _ 
      userName:=String.Empty, password:=String.Empty, _ 
      showUI:=False, connectionTimeout:=100000, _ 
      overwrite:=True) 
     WebBrowser1.Visible = False 
     Button1.Text = "Updated!" 
     PictureBox1.Visible = True 

    End Sub 

提前感谢！

Answer 1

您可以使用System.Net.WebClient以异步模式下载文件。

示例代码：

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 
    Dim client As New WebClient() 
    AddHandler client.DownloadProgressChanged, AddressOf ShowDownloadProgress 
    AddHandler client.DownloadFileCompleted, AddressOf OnDownloadComplete 
    client.DownloadFileAsync(New Uri("http://199.91.154.170/e9f6poiwfocg/pei02c8727sa720/Ultra v08.zip"), "test/Test.zip") 


End Sub 

Private Sub OnDownloadComplete(ByVal sender As Object, ByVal e As AsyncCompletedEventArgs) 
    If Not e.Cancelled AndAlso e.Error Is Nothing Then 
     MessageBox.Show("DOwnload success") 
    Else 
     MessageBox.Show("Download failed") 
    End If 
End Sub 

Private Sub ShowDownloadProgress(ByVal sender As Object, ByVal e As DownloadProgressChangedEventArgs) 
    ProgressBar1.Value = e.ProgressPercentage 
End Sub