asp.net - ASP.NET Web API 完成向客户端发送时是否有通知

Question

我正在使用 Web API 将大文件流式传输到客户端，但我想记录下载是否成功。也就是说，如果服务器发送了文件的全部内容。

有什么方法可以在 HttpResponseMessage 时获得回调或事件完成发送数据？

也许是这样的:

var stream = GetMyStream();
var response = new HttpResponseMessage(HttpStatusCode.OK);
response.Content = new StreamContent(stream);
response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");    
// This doesn't exist, but it illustrates what I'm trying to do.
response.OnComplete(context =>
{
    if (context.Success)
        Log.Info("File downloaded successfully.");
    else
        Log.Warn("File download was terminated by client.");
});

Answer 1

编辑:我现在已经使用真实连接(通过 fiddler )对此进行了测试。

我继承了StreamContent并添加了我自己的 OnComplete检查异常的操作:

public class StreamContentWithCompletion : StreamContent
{
    public StreamContentWithCompletion(Stream stream) : base (stream) { }
    public StreamContentWithCompletion(Stream stream, Action<Exception> onComplete) : base(stream) 
    { 
        this.OnComplete = onComplete; 
    }

    public Action<Exception> OnComplete { get; set; }

    protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
    {
        var t = base.SerializeToStreamAsync(stream, context);
        t.ContinueWith(x =>
        {
            if (this.OnComplete != null)
            {
                // The task will be in a faulted state if something went wrong. 
                // I observed the following exception when I aborted the fiddler session: 
                // 'System.Web.HttpException (0x800704CD): The remote host closed the connection.'
                if (x.IsFaulted)
                    this.OnComplete(x.Exception.GetBaseException());
                else
                    this.OnComplete(null);
            }
        }, TaskContinuationOptions.ExecuteSynchronously);
        return t;
    }
}

然后我像这样使用它:

var stream = GetMyStream();
var response = new HttpResponseMessage(HttpStatusCode.OK);
response.Content = new StreamContentWithCompletion(stream, ex =>
{
    if (ex == null)
        Log.Info("File downloaded successfully.");
    else
        Log.Warn("File download was terminated by client.");
});
response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");    
return response;