win8 metro HttpClient下载文件-带进度条

来源：互联网发布：php 一句话木马菜刀编辑：程序博客网时间：2024/05/05 03:21

HttpClient 直接下载文件，如果文件比较大，没有进度显示会很不友好，

所有在下载的时候希望下载一部分就显示一下进度。

代码的重点是

HttpCompletionOption.ResponseHeadersRead

以及

ReadAsStreamAsync

对于dispose，也可以用using。

var saveFile = await ApplicationData.Current.LocalFolder.CreateFileAsync(filename,                        CreationCollisionOption.ReplaceExisting);                    var fs = await saveFile.OpenAsync(FileAccessMode.ReadWrite);                    HttpClientHandler handler = new HttpClientHandler();                    handler.ClientCertificateOptions = ClientCertificateOption.Automatic;                    HttpClient hc = new HttpClient(handler);                    HttpResponseMessage response = await hc.GetAsync(DownUrl, HttpCompletionOption.ResponseHeadersRead);                    Stream stream = await response.Content.ReadAsStreamAsync();                    IInputStream inputStream = stream.AsInputStream();                    ulong totalBytesRead = 0;                    while (true)                    {                        // Read from the web.                        IBuffer buffer = new Buffer(1024);                        buffer = await inputStream.ReadAsync(                            buffer,                            buffer.Capacity,                            InputStreamOptions.None);                        if (buffer.Length == 0)                        {                            // 完成                            break;                        }                        // 进度                        totalBytesRead += buffer.Length;                        System.Diagnostics.Debug.WriteLine("Bytes read: {0}", totalBytesRead);                        // 写文件.                        await fs.WriteAsync(buffer);                    }                    inputStream.Dispose();                    fs.Dispose();

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