在Windows Phone 8中以编程方式下载媒体文件 [英] Downloading Media File programmatically in Windows Phone 8

问题描述

我们的应用程序是基于视频/音频的应用程序，并且我们已将所有媒体上传到Windows Azure.

Our app is video/audio based app, and we have uploaded all the media on Windows Azure.

但是，需要方便用户按需下载音频/视频文件，以便他们可以在本地播放.

However it is required to facilitate user to download audio/video file on demand, so that they can play it locally.

因此，我需要以编程方式下载音频/视频文件，并将其保存在IsolatedStorage中.

So i need to download audio/video file programmatically and save it in IsolatedStorage.

我们为每个音频/视频提供Windows Azure媒体文件访问URL.但是我陷入了下载媒体文件的第一步.

We have Windows Azure Media File Access URLs for each audio/video. But I am stuck in 1st step of downloading media file.

我用Google搜索并遇到了

I googled and came across this article, but for WebClient there is no function DownloadFileAsync that I can use.

但是，我尝试了其其他功能DownloadStringAsyn，并且下载的媒体文件为字符串格式，但不知道如何将其转换为音频(wma)/视频(mp4)格式.请提出建议，我该如何进行?还有其他下载媒体文件的方法吗?

However I tried its other function DownloadStringAsyn, and download media file is in string format but don't know how to convert it to audio(wma)/video(mp4) format. Please suggest me, how can I proceed? Is there other way to download media file?

这是我使用的示例代码

private void ApplicationBarMenuItem_Click_1(object sender, EventArgs e)
    {
        WebClient mediaWC = new WebClient();
        mediaWC.DownloadProgressChanged += new DownloadProgressChangedEventHandler(mediaWC_DownloadProgressChanged);
        mediaWC.DownloadStringAsync(new Uri(link));            
        mediaWC.DownloadStringCompleted += new DownloadStringCompletedEventHandler(mediaWC_DownloadCompleted);           

    }

    private void mediaWC_DownloadCompleted(object sender, DownloadStringCompletedEventArgs e)
    {
        if (e.Cancelled)
            MessageBox.Show("Downloading is cancelled");
        else
        {
            MessageBox.Show("Downloaded");
        }
    }   

    private void mediaWC_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
    {
        statusbar.Text = status= e.ProgressPercentage.ToString();
    }

推荐答案

将其保存在工具箱中:)

Save this in your toolbox :)

    public static Task<Stream> DownloadFile(Uri url)
    {
        var tcs = new TaskCompletionSource<Stream>();
        var wc = new WebClient();
        wc.OpenReadCompleted += (s, e) =>
        {
            if (e.Error != null) tcs.TrySetException(e.Error);
            else if (e.Cancelled) tcs.TrySetCanceled();
            else tcs.TrySetResult(e.Result);
        };
        wc.OpenReadAsync(url);
        return tcs.Task;
    }

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