net4.x MVC架构迁移到asp.net core的HttpContext问题

• HttpContext

在Asp.net 4.x时代，我们通常的做法是通过HttpContext.Current获取当前请求的上下文进而获取到当前的User属性，所以问题的切入点在于我们如何获取当前的HttpContext上下文。

　　在我们的Aspnet Core应用中，系统是通过注入HttpContext的访问器对象IHttpContextAccessor来获取当前的HttpContext。

• 参考资源：
  • https://www.cnblogs.com/linezero/p/6801602.html(未经验证)
  • https://www.cnblogs.com/lex-wu/p/10528109.html(未经验证)
  • 参考OrchardCore：src\OrchardCore\OrchardCore\Modules\DefaultOrchardHelper.cs

•  首先要在程序启动时注册到容器中HttpContextAccessor

/// <summary>
        /// Register HttpContextAccessor
        /// </summary>
        /// <param name="services">Collection of service descriptors</param>
        public static void AddHttpContextAccessor(this IServiceCollection services)
        {
            services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
        }

• Controllers因为引用了Microsoft.AspNetCore.Mvc;命令空间可以直接使用

public virtual IActionResult GeneralCommon()
        {
            if (!_permissionService.Authorize(StandardPermissionProvider.ManageSettings))
                return AccessDeniedView();

            //prepare model
            var model = _settingModelFactory.PrepareGeneralCommonSettingsModel();

            //notify admin that CSS bundling is not allowed in virtual directories
            if (model.MinificationSettings.EnableCssBundling && HttpContext.Request.PathBase.HasValue)
                _notificationService.WarningNotification(_localizationService.GetResource("Admin.Configuration.Settings.GeneralCommon.EnableCssBundling.Warning"));

            return View(model);
        }

• 中间件中使用HttpContext 

public Task Invoke(Microsoft.AspNetCore.Http.HttpContext context, IWebHelper webHelper, IWorkContext workContext)
        {
            //set culture
            SetWorkingCulture(webHelper, workContext);

            //call the next middleware in the request pipeline
            return _next(context);
        }

• 其他层则需要由容器注入后再使用，可以参考以下OrchardCore对HttpContent的定义和调用。

namespace OrchardCore.Modules
{
    public class DefaultOrchardHelper : IOrchardHelper
    {
        public DefaultOrchardHelper(IHttpContextAccessor httpContextAccessor)
        {
            HttpContext = httpContextAccessor.HttpContext;
        }

        public HttpContext HttpContext { get; set; }
    }
}