asp.net mvc输出自定义404等错误页面，非302跳转。

朋友问到一个问题，如何输出自定义错误页面，不使用302跳转。当前页面地址不能改变.

还要执行一些代码等,生成一些错误信息,方便用户提交反馈.

500错误，mvc框架已经有现成解决方法：

filters.Add(new HandleErrorAttribute());

404错误目前想到的解决方法：

先上代码 Global.asax：

protected void Application_Error(object sender, EventArgs e)
        {
            var ex = Server.GetLastError() as HttpException;
            if (ex == null)
                return;

            var httpStatusCode = ex.GetHttpCode();

            if (httpStatusCode == 404)
            {
                var httpContext = (sender as MvcApplication).Context;

                httpContext.ClearError();
                httpContext.Response.Clear();
                httpContext.Response.StatusCode = 404;
                ServiceFocus.LogService.AddLog(ex);

                httpContext.Response.ContentType = "text/html; charset=utf-8";
                var routeData = new RouteData();
                routeData.Values["controller"] = "Sys";
                routeData.Values["action"] = "NotFound";
                var requestContext = new RequestContext(new HttpContextWrapper(httpContext), routeData);
                var controller = ControllerBuilder.Current.GetControllerFactory().CreateController(requestContext, "Sys") as SysController;
                //controller.ViewData.Model=model;
                (controller as IController).Execute(requestContext);
                ControllerBuilder.Current.GetControllerFactory().ReleaseController(controller);
            }
        }

controller代码：

public class CompressAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            var acceptEncoding = filterContext.HttpContext.Request.Headers["Accept-Encoding"];
            if (!string.IsNullOrEmpty(acceptEncoding))
            {
                acceptEncoding = acceptEncoding.ToLower();
                var response = filterContext.HttpContext.Response;
                if (acceptEncoding.Contains("gzip"))
                {
                    response.AppendHeader("Content-encoding", "gzip");
                    response.Filter = new GZipStream(response.Filter, CompressionMode.Compress);
                }
                else if (acceptEncoding.Contains("deflate"))
                {
                    response.AppendHeader("Content-encoding", "deflate");
                    response.Filter = new DeflateStream(response.Filter, CompressionMode.Compress);
                }
            }
        }
    }
    [Compress]
    public class SysController : Controller
    {
        //
        // GET: /sys/

        public ActionResult NotFound()
        {
            return View();
        }
        public ActionResult Error()
        {
            return View();
        }
    }

web.config

<system.webServer>
    <httpErrors errorMode="Detailed" />

目前有几个疑惑，没有深究：还望有网友知道能解惑一二，就不用去google 扒源码了。

1.如果不加这行代码，默认输出的是：text/html; 浏览器直接输出内容,不做解析.

httpContext.Response.ContentType = "text/html; charset=utf-8";

2.iis不会使用gzip压缩,不管输出的404错误页面有多大,都不会自动压缩.所以使用下面这种替换方式.

　　[Compress]
    public class SysController : Controller

猜测:

mvc 在action的Execute阶段后 还做了不少事情,比如上面提到的1,2点.正常200请求会执行默认的filter等阶段.

而当是404请求时,跳过了这些阶段.可能500请求也类似.

仅仅是猜测,还未验证,