C# 如何从Silverlight中的HttpWebRequest.BeginGetRequestStream中更新UI

我正在使用HttpWebRequest的BeginGetRequestStream上载多个文件，但我想在发布数据流时更新我编写的进度控制

如何做到这一点，我已经尝试从将数据推送到流中的循环中调用Dispatch.BeginInvoke（如下所示），但它会锁定浏览器直到完成，因此它似乎处于某种工作线程/ui线程死锁状态

这是我正在做的工作的代码片段：

class RequestState
{
    public HttpWebRequest request;  // holds the request
    public FileDialogFileInfo file; // store our file stream data

    public RequestState( HttpWebRequest request, FileDialogFileInfo file )
    {
        this.request = request;
        this.file = file;
    }
}

private void UploadFile( FileDialogFileInfo file )
{
    UriBuilder ub = new UriBuilder( app.receiverURL );
    ub.Query = string.Format( "filename={0}", file.Name );

    // Open the selected file to read.
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create( ub.Uri );
    request.Method = "POST";

    RequestState state = new RequestState( request, file );
    request.BeginGetRequestStream( new AsyncCallback( OnUploadReadCallback ), state );
}

private void OnUploadReadCallback( IAsyncResult asynchronousResult )
{
    RequestState state = (RequestState)asynchronousResult.AsyncState;
    HttpWebRequest request = (HttpWebRequest)state.request;

    Stream postStream = request.EndGetRequestStream( asynchronousResult );
    PushData( state.file, postStream );
    postStream.Close();

    state.request.BeginGetResponse( new AsyncCallback( OnUploadResponseCallback ), state.request );
}

private void PushData( FileDialogFileInfo file, Stream output )
{
    byte[] buffer = new byte[ 4096 ];
    int bytesRead = 0;

    Stream input = file.OpenRead();
    while( ( bytesRead = input.Read( buffer, 0, buffer.Length ) ) != 0 )
    {
        output.Write( buffer, 0, bytesRead );
        bytesReadTotal += bytesRead;

        App app = App.Current as App;
        int totalPercentage = Convert.ToInt32( ( bytesReadTotal / app.totalBytesToUpload ) * 100 );

        // enabling the following locks up my UI and browser
        Dispatcher.BeginInvoke( () =>
        {
            this.ProgressBarWithPercentage.Percentage = totalPercentage;
        } );
    }
}

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我想说的是，我不认为Silverlight 2的HttpWebRequest支持流式传输，因为请求数据完全被缓冲到内存中。不过，我上次看它已经有一段时间了，所以我回去看看Beta 2是否支持它。事实证明确实如此。我很高兴我在陈述之前回去阅读了。您可以通过将AllocreadStreamBuffering设置为false来启用它。您是否在HttpWebRequest上设置了此属性？这可能会导致你的阻塞

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编辑，为您找到另一个参考。您可能希望通过将文件分成块来遵循这种方法。这是去年3月写的，因此我不确定它是否能在Beta 2中使用。

谢谢你，我会看看这些链接，我一直在考虑将数据分块，这似乎是我从中获得合理进度报告的唯一方法