實現的原理比較直接，定義一個MessageHandler記錄WebAPI的請求記錄，然後將這些請求日誌推送到客戶端，客戶端就是一個查看日誌的頁面，實時將請求日誌展示在頁面中。 這個例子的目的是演示如何在PersistentConnection類外部給Clients推送消息 實現過程 一、服務端 服務 ...
實現的原理比較直接，定義一個MessageHandler記錄WebAPI的請求記錄，然後將這些請求日誌推送到客戶端，客戶端就是一個查看日誌的頁面，實時將請求日誌展示在頁面中。
這個例子的目的是演示如何在PersistentConnection類外部給Clients推送消息
實現過程
一、服務端
服務端同時具備SignalR和WebAPI的功能，通過定義一個記錄日誌的MessageHandler實現對WebAPI請求的攔截，並生成請求記錄，然後推送到客戶端
step 1
創建一個具備WebAPI功能的站點，為了簡化起見，設置Authentication為No Authentication
step 2
創建一個DelegatingHandler，用於記錄WebAPI日誌，代碼如下
下麵代碼沒有涉及到SignalR的功能，日誌展示是通過ILoggingDisplay介面傳入
public class LoggingHandler : DelegatingHandler { private static readonly string _loggingInfoKey = "loggingInfo"; private ILoggingDisplay _loggingDisplay; public LoggingHandler(ILoggingDisplay loggingDisplay) { _loggingDisplay = loggingDisplay; } public LoggingHandler(HttpMessageHandler innerHandler, ILoggingDisplay loggingDisplay) : base(innerHandler) { _loggingDisplay = loggingDisplay; } protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { LogRequestLoggingInfo(request); return base.SendAsync(request, cancellationToken).ContinueWith(task => { var response = task.Result; LogResponseLoggingInfo(response); return response; }); } private void LogRequestLoggingInfo(HttpRequestMessage request) { var info = new ApiLoggingInfo(); info.HttpMethod = request.Method.Method; info.UriAccessed = request.RequestUri.AbsoluteUri; info.IpAddress = HttpContext.Current != null ? HttpContext.Current.Request.UserHostAddress : "0.0.0.0"; info.StartTime = DateTime.Now; ExtractMessageHeadersIntoLoggingInfo(info, request.Headers.ToList()); request.Properties.Add(_loggingInfoKey, info); } private void LogResponseLoggingInfo(HttpResponseMessage response) { object loggingInfoObject = null; if (!response.RequestMessage.Properties.TryGetValue(_loggingInfoKey, out loggingInfoObject)) { return; } var info = loggingInfoObject as ApiLoggingInfo; if (info == null) { return; } info.HttpMethod = response.RequestMessage.Method.ToString(); info.ResponseStatusCode = response.StatusCode; info.ResponseStatusMessage = response.ReasonPhrase; info.UriAccessed = response.RequestMessage.RequestUri.AbsoluteUri; info.IpAddress = HttpContext.Current != null ? HttpContext.Current.Request.UserHostAddress : "0.0.0.0"; info.EndTime = DateTime.Now; info.TotalTime = (info.EndTime - info.StartTime).TotalMilliseconds; _loggingDisplay.Display(info); } private void ExtractMessageHeadersIntoLoggingInfo(ApiLoggingInfo info, List<KeyValuePair<string, IEnumerable<string>>> headers) { headers.ForEach(h => { var headerValues = new StringBuilder(); if (h.Value != null) { foreach (var hv in h.Value) { if (headerValues.Length > 0) { headerValues.Append(", "); } headerValues.Append(hv); } } info.Headers.Add(string.Format("{0}: {1}", h.Key, headerValues.ToString())); }); } }LoggingHandler
step 3
引入SignalR相關packages
Install-Package Microsoft.AspNet.SignalR
新建一個PersistentConnection，代碼為空即可（因為不涉及到客戶端調用，推送也是在類的外部執行）
public class RequestMonitor : PersistentConnection
{
}
添加一個Startup類
public void Configuration(IAppBuilder app)
{
app.MapSignalR<RequestMonitor>("/monitor");
}
step 4
創建一個類實現ILoggingDisplay介面，用SignalR推送的方式實現這個介面
代碼比較關鍵的部分就是通過GlobalHost.ConnectionManager獲取當前應用程式的connectionContext,得到這個context就可以類似在PersistentConnection內部給clients推送消息
public class SignalRLoggingDisplay : ILoggingDisplay { /// <summary> /// PersistentConnection上下文 /// </summary> private static IPersistentConnectionContext connectionContext = GlobalHost.ConnectionManager.GetConnectionContext<RequestMonitor>(); public void Display(ApiLoggingInfo loggingInfo) { var message = new StringBuilder(); message.AppendFormat("StartTime:{0},Method:{1},Url:{2},ReponseStatus:{3},TotalTime:{4}" , loggingInfo.StartTime, loggingInfo.HttpMethod, loggingInfo.UriAccessed, loggingInfo.ResponseStatusCode, loggingInfo.TotalTime); message.AppendLine(); message.AppendFormat("Headers:{0},Body:{1}", string.Join(",", loggingInfo.Headers), loggingInfo.BodyContent); connectionContext.Connection.Broadcast(message.ToString()); }SignalRLoggingDisplay
step 5
在WebApiConfig的Register方法中添加自定義的handler
public static void Register(HttpConfiguration config) { config.MapHttpAttributeRoutes(); config.Routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = RouteParameter.Optional } ); config.MessageHandlers.Add(new LoggingHandler(new SignalRLoggingDisplay())); }RegisterHandler
到此完成服務端的功能實現
二、客戶端
客戶端只需要一個監控頁面，html頁面足矣，其主要功能是提供開始監控、停止監控功能，其他都是接收服務端的推送並展示功能代碼。
<!DOCTYPE html> <html> <head> <title>Web API頁面實時請求監控</title> <meta charset="utf-8" /> </head> <body> <h1>Web API Request Logs</h1> <div> <input type="button" value="start" id="btnStart"/> <input type="button" value="stop" id="btnStop"/> <input type="button" value="clear" id="btnClear"/> </div> <ul id="requests"></ul> <script src="/Scripts/jquery-1.10.2.min.js"></script> <script src="/Scripts/jquery.signalR-2.2.0.min.js"></script> <script> $(function () { var requests = $("#requests"); var startButton = $("#btnStart"); var stopButton = $("#btnStop"); var connection = null; enable(stopButton, false); enable(startButton, true); startButton.click(function () { startConnection(); enable(stopButton, true); enable(startButton, false); }); $("#btnClear").click(function () { $("#requests").children().remove(); }); stopButton.click(function () { stopConnection(); enable(stopButton, false); enable(startButton, true); }); function startConnection() { stopConnection(); connection = $.connection("/monitor"); connection.start() .fail(function () { console.log("connect failed"); }); connection.received(function (data) { data = data.replace(/\r\n/g, "<br/>") data = data.replace(/\n/g, "<br/>"); requests.append("<li>" + data + "</li>"); }); } function stopConnection() { if (connection != null){ connection.stop(); } } function enable(button, enabled) { if (enabled) { button.removeAttr("disabled"); } else { button.attr("disabled", "disabled"); } } }); </script> </body> </html>Monitor
示例代碼下載
