.net core添加自定义中间件小例子

声明自定义中间件及处理方法

 public class RequestSetOptionsMiddleware
    {
        /// <summary>
        /// 可以处理HTTP请求的函数
        /// </summary>
        private readonly RequestDelegate _next;

        public RequestSetOptionsMiddleware(RequestDelegate next)
        {
            _next = next;
        }

        /// <summary>
        /// 执行当前自定义中间件的处理
        /// 注意自定义中间件名字必须为Invoke或者InvokeAsync
        /// </summary>
        /// <param name="httpcontext"></param>
        /// <returns></returns>
        public async Task Invoke(HttpContext httpcontext)
        {
            //获取httpcontext请求中的option参数
            var option = httpcontext.Request.Query["option"];

            if (!string.IsNullOrWhiteSpace(option))
            {

                httpcontext.Items["option"] = WebUtility.HtmlEncode(option);
            }

            await _next(httpcontext);
        }


    }

  /// <summary>
    /// 继承IStartupFilter接口
    /// </summary>
    public class RequestSetOptionsStartupFilter : IStartupFilter
    {
        /// <summary>
        /// 构造配置
        /// </summary>
        /// <param name="next"></param>
        /// <returns></returns>
        public Action<IApplicationBuilder> Configure(Action<IApplicationBuilder> next)
        {
            return builder =>
            {
                //引用自定义中间件
                builder.UseMiddleware<RequestSetOptionsMiddleware>();
                //管道继续运行
                next(builder);
            };
        }
    }

在Startup.cs引用自定义中间件：

 public void ConfigureServices(IServiceCollection services)
        {
            services.AddTransient<IStartupFilter, RequestSetOptionsStartupFilter>();
          
        }

实现效果如下：

模拟请求

自定义中间件获取httpcontext并进行相应的处理