ASP.NET Core中间件计算Http请求时间示例详解

public delegate Task RequestDelegate(HttpContext context);

public static IApplicationBuilder Use(this IApplicationBuilder app, Func<HttpContext, Func<Task>, Task> middleware);public static IApplicationBuilder UseMiddleware<TMiddleware>(this IApplicationBuilder app, params object[] args);

public class ResponseTimeMiddleware{  // Name of the Response Header, Custom Headers starts with "X-"   private const string RESPONSE_HEADER_RESPONSE_TIME = "X-Response-Time-ms";  // Handle to the next Middleware in the pipeline   private readonly RequestDelegate _next;  public ResponseTimeMiddleware(RequestDelegate next)  {    _next = next;  }  public Task InvokeAsync(HttpContext context)  {    // Start the Timer using Stopwatch     var watch = new Stopwatch();    watch.Start();    context.Response.OnStarting(() => {      // Stop the timer information and calculate the time        watch.Stop();      var responseTimeForCompleteRequest = watch.ElapsedMilliseconds;      // Add the Response time information in the Response headers.        context.Response.Headers[RESPONSE_HEADER_RESPONSE_TIME] = responseTimeForCompleteRequest.ToString();      return Task.CompletedTask;    });    // Call the next delegate/middleware in the pipeline      return this._next(context);  }}