public void ConfigureServices(IServiceCollection services)
        {
           
            #region Cors跨域请求
            services.AddCors(c =>
            {
                c.AddPolicy("AllRequests", policy =>
                {
                    policy
                    .AllowAnyOrigin()
                    .AllowAnyMethod()
                    .AllowAnyHeader();

                });
            });
            #endregion

            services.AddControllers();
        }

  public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseRouting();

           
            //开启Cors跨域请求中间件
            app.UseCors("AllRequests");

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }