c# - 异步下载时设置用户状态

Question

VS 2008 SP1

我正在使用网络客户端异步下载一些文件。

我有 5 个文件要下载。

但是，我想监控每次下载并想将用户状态设置为文件的名称，所以在 ProgressCompletedEvent 中我可以检查用户状态以查看哪个文件已完成？

他是我正在尝试做的事情的简短代码片段。

// This function will be called for each file that is going to be downloaded.
// is there a way I can set the user state so I know that the download 
// has been completed 
// for that file, in the DownloadFileCompleted Event? 
private void DownloadSingleFile()
{
    if (!wb.IsBusy)
    {        
        //  Set user state here       
        wb.DownloadFileAsync(new Uri(downloadUrl), installationPath);
    }
}


void wb_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
{
    Console.WriteLine("File userstate: [ " + e.UserState + " ]");   
}

void wb_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
    Console.WriteLine("File userstate: [ " + e.UserState + " ]");   

    double bytesIn = double.Parse(e.BytesReceived.ToString());
    double totalBytes = double.Parse(e.TotalBytesToReceive.ToString());
    double percentage = bytesIn / totalBytes * 100;

    progressBar1.Value = int.Parse(Math.Truncate(percentage).ToString());

}

Answer 1

您可以将任何对象作为第三个​​ 参数传递给 DownloadFileAsync() 调用，您将把它作为 userState 取回。在你的情况下，你可以简单地传递你的文件名。