ASP.NET Core 404 中间件

中间件示例：

using AuthCenter.Domain.Modules;
using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

namespace AuthCenter.Domain.Middlewares
{
    /// <summary>
    /// 404 中间件
    /// </summary>
    public class NotFoundMiddleware
    {
        // json 序列化配置
        private static readonly JsonSerializerOptions JsonSetting = new JsonSerializerOptions()
        {
            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
            WriteIndented = true
        };

        private readonly RequestDelegate _next;

        /// <summary>
        /// 404 中间件
        /// </summary>
        /// <param name="next">委托</param>
        public NotFoundMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        /// <summary>
        /// 委托
        /// </summary>
        /// <param name="context"></param>
        /// <returns></returns>
        public async Task Invoke(HttpContext context)
        {
            if (context == null)
            {
                throw new ArgumentNullException(nameof(context));
            }

            await _next(context);

            if (context.Response.StatusCode != 404)
            {
                return;
            }
            var result = new ResponseJsonResultModel<string>
            {
                Code = 404,
                Msg = $"所请求的 {context.Request.Path} 地址不存在",
                Data = context.Request.Path
            };
            await context.Response.WriteAsync(JsonSerializer.Serialize(result, JsonSetting));
        }
    }
}

使用中间件：

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseMiddleware<NotFoundMiddleware>();
            }