从网上下载多个文件

我正在研究一些应用程序，以便从url下载不同日期的股票价格文件。我使用下面的代码从网上下载多个文件

Conn = New OdbcConnection("DSN=RA;MultipleActiveResultSets=True") 
    If Conn.State = ConnectionState.Closed Then 
     Conn.Open() 
    End If 
    Dim mont As Date 
    mont = DateTimePicker1.Value 
    Dim dnldurlA As String = "http://www.nseindia.com/content/historical/EQUITIES/" 
    Dim dnldurlB As String = UCase(mont.ToString("MMM")) 
    Dim dnldurlC As String = "/" 
    Dim dnldurlD As String = "cm" 
    Dim dnldurlE As String = mont.ToString("dd") 
    Dim dnldurlF As String = mont.ToString("yyyy") 
    Dim dnldurlG As String = "bhav" 
    Dim dnldurlH As String = ".csv" 
    Dim dnldurlI As String = ".zip" 
    Dim dnldurlJ As String = "\" 
    Dim FileName As String = dnldurlE & dnldurlB & dnldurlF & ".ZIP" 
    Try 
     Dim downloadClient As New WebClient() 
     downloadClient.Headers("Accept") = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8" 
     downloadClient.Headers("User-Agent") = "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.83 Safari/537.1" 
     Dim dnldurl As String = dnldurlA & dnldurlF & dnldurlC & dnldurlB & dnldurlC & dnldurlD & dnldurlE & dnldurlB & dnldurlF & dnldurlG & dnldurlH & dnldurlI 
     downloadClient.DownloadFile(New Uri(dnldurl), ("C:\" & FileName)) 
     While (downloadClient.IsBusy = True) 

     End While 
     downloadClient.Dispose() 
    Catch ex As Exception 
     MsgBox("File can not be downloaded!!!") 
     Me.Close() 
    End Try

我下载的第一个文件，当我选择其他日期后的文件坚持了，它抛出一个错误 {“远程服务器返回错误：禁止（403） “} 但是，当我退出应用程序并再次尝试相同的日期时，文件即时下载。

请帮

在此先感谢克里斯

来源

2017-08-25 Kris

它可能是某种保护的网站添加防止人们迅速下载许多东西。有些网站只希望人们浏览并提供API来下载信息。 –

我对代码做了一些调整。无论如何，它在相当一段时间都令人困扰。谢谢 – Kris

假设你在循环中做这样的事情，你可以添加一个小的延迟来避免被限制。 – Plutonix

我只是做了一个小的变化，它的工作完美

Conn = New OdbcConnection("DSN=RA;MultipleActiveResultSets=True") 
    If Conn.State = ConnectionState.Closed Then 
     Conn.Open() 
    End If 
    Dim mont As Date 
    mont = DateTimePicker1.Value 
    Dim dnldurlA As String = "http://www.nseindia.com/content/historical/EQUITIES/" 
    Dim dnldurlB As String = UCase(mont.ToString("MMM")) 
    Dim dnldurlC As String = "/" 
    Dim dnldurlD As String = "cm" 
    Dim dnldurlE As String = mont.ToString("dd") 
    Dim dnldurlF As String = mont.ToString("yyyy") 
    Dim dnldurlG As String = "bhav" 
    Dim dnldurlH As String = ".csv" 
    Dim dnldurlI As String = ".zip" 
    Dim dnldurlJ As String = "\" 
    Dim FileName As String = dnldurlE & dnldurlB & dnldurlF & ".ZIP" 
    Try 
     Dim downloadClient As New WebClient() 
     Dim dnldurl As String = dnldurlA & dnldurlF & dnldurlC & dnldurlB & dnldurlC & dnldurlD & dnldurlE & dnldurlB & dnldurlF & dnldurlG & dnldurlH & dnldurlI 
     downloadClient.DownloadFile(New Uri(dnldurl), ("C:\" & FileName)) 
     While (downloadClient.IsBusy = True) 

     End While 
     downloadClient.Dispose() 
    Catch ex As Exception 
     MsgBox("File can not be downloaded!!!") 
     Me.Close() 
    End Try

感谢

来源

2017-08-25 15:49:33 Kris

从网上下载多个文件

回答

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