下载前请求文件大小 [英] Request file size before download it

问题描述

我目前使用 Net.WebClient 从 Internet 下载文件.现在，我想做另一件事.只有在我使用这个子中的参数 e.TotalBytesToReceive 开始下载后，我才能知道苍蝇的大小

I'm currently usign a Net.WebClient to download a file from the Internet. Now, I'd like to do another thing. I can know the flie size only after I started download with the parameter e.TotalBytesToReceive inside this sub

    Private Sub W_DownloadProgressChanged(ByVal sender As Object, ByVal e As _
    Net.DownloadProgressChangedEventArgs) Handles W.DownloadProgressChanged

如何在不下载的情况下获取链接的文件大小参数?

How can I get the file size parameter of a link without downloading it?

推荐答案

使用 WebClient ResponseHeaders:

Public Shared Function GetFileSize(url As String) As Long
    Using obj As New WebClient()
        Using s As Stream = obj.OpenRead(url)
            Return Long.Parse(obj.ResponseHeaders("Content-Length").ToString())
        End Using
    End Using
End Function

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