當ASP.NET Web API完成發送到客戶端時是否有通知

Question

我正在使用Web API將大文件傳輸到客戶端，但我想記錄下載是否成功。也就是說，如果服務器發送了整個文件的內容。

當HttpResponseMessage完成發送數據時，是否有某種方法可以獲得回調或事件？

也許是這樣的：

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

編輯：我現在一直在使用一個真正的連接（通過小提琴手）測試此。

我繼承StreamContent，並加入我自己的OnComplete行動，檢查了異常：

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; 
    } 
} 

然後我用它像這樣：

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; 

Answer 2

我不知道是否有直接的信號，一切都OK，但你可以用一招地發現，你最終它之前的連接存在，並在您完全發送文件後。

例如，Response.IsClientConnected是返回真，如果客戶端仍連接，使您可以檢查類似：

// send the file, make a flush 
Response.Flush(); 
// and now the file is fully sended check if the client is still connected 
if(Response.IsClientConnected) 
{ 
    // log that all looks ok until the last byte. 
} 
else 
{ 
    // the client is not connected, so maybe have lost some data 
} 

// and now close the connection. 
Response.End(); 

Answer 3

如果服務器發送的全部內容文件

其實沒有興奮:)

這聽起來很簡單，但你會知道是否引發異常 - 如果你關心服務器交付而不是客戶端取消中途。 IsClientConnected基於ASP.NET HttpResponse而不是WebApi。