.net webapi action拦截器 统计action耗时

//执行action前执行这个方法
public override void OnActionExecuting(HttpActionContext filterContext)
{
      //用于计算消耗时间
      var stopWatch = new Stopwatch();
      filterContext.Request.Properties[Key] = stopWatch;
      stopWatch.Start();
}

//执行action后执行这个方法
public override void OnActionExecuted(HttpActionExecutedContext filterContext)
{
      var stopWatch = filterContext.Request.Properties[Key] as Stopwatch;
      if (stopWatch != null)
      {
           stopWatch.Stop();
           TimeSpan time = stopWatch.Elapsed;
      }
}