想必只要 接触了 net core的小伙伴们 已经发现 @html.Action()方法 官方已经不提供支持了，转而使用 ViewComponents替代了，同时也增加了TagHelper。但是 如果想用以前的@Html.Action()方法，我们其实可以自己动手去实现它。
下面就开始 实现之旅吧！
1、创建 静态类 HtmlHelperViewExtensions，其命名空间为 Microsoft.AspNetCore.Mvc.Rendering。这样我们直接用@Html直接可以 使用Action方法了。
using Microsoft.AspNetCore.Html;using Microsoft.AspNetCore.Http;using Microsoft.AspNetCore.Mvc.Infrastructure;using Microsoft.AspNetCore.Routing;using Microsoft.Extensions.DependencyInjection;using System;using System.IO;using System.Threading.Tasks;namespace Microsoft.AspNetCore.Mvc.Rendering{ ???public static class HtmlHelperViewExtensions ???{ ???????public static IHtmlContent Action(this IHtmlHelper helper, string action, object parameters = null) ???????{ ???????????var controller = (string)helper.ViewContext.RouteData.Values["controller"]; ???????????return Action(helper, action, controller, parameters); ???????} ???????public static IHtmlContent Action(this IHtmlHelper helper, string action, string controller, object parameters = null) ???????{ ???????????var area = (string)helper.ViewContext.RouteData.Values["area"]; ???????????return Action(helper, action, controller, area, parameters); ???????} ???????public static IHtmlContent Action(this IHtmlHelper helper, string action, string controller, string area, object parameters = null) ???????{ ???????????if (action == null) ???????????????throw new ArgumentNullException("action"); ???????????if (controller == null) ???????????????throw new ArgumentNullException("controller"); ???????????var task = RenderActionAsync(helper, action, controller, area, parameters); ???????????return task.Result; ???????} ???????private static async Task<IHtmlContent> RenderActionAsync(this IHtmlHelper helper, string action, string controller, string area, object parameters = null) ???????{ ???????????// fetching required services for invocation ???????????var serviceProvider = helper.ViewContext.HttpContext.RequestServices; ???????????var actionContextAccessor = helper.ViewContext.HttpContext.RequestServices.GetRequiredService<IActionContextAccessor>(); ???????????var httpContextAccessor = helper.ViewContext.HttpContext.RequestServices.GetRequiredService<IHttpContextAccessor>(); ???????????var actionSelector = serviceProvider.GetRequiredService<IActionSelector>(); ???????????// creating new action invocation context ???????????var routeData = new RouteData(); ???????????foreach (var router in helper.ViewContext.RouteData.Routers) ???????????{ ???????????????routeData.PushState(router, null, null); ???????????} ???????????routeData.PushState(null, new RouteValueDictionary(new { controller = controller, action = action, area = area }), null); ???????????routeData.PushState(null, new RouteValueDictionary(parameters ?? new { }), null); ???????????//get the actiondescriptor ???????????RouteContext routeContext = new RouteContext(helper.ViewContext.HttpContext) { RouteData = routeData }; ???????????var candidates = actionSelector.SelectCandidates(routeContext); ???????????var actionDescriptor = actionSelector.SelectBestCandidate(routeContext, candidates); ???????????var originalActionContext = actionContextAccessor.ActionContext; ???????????var originalhttpContext = httpContextAccessor.HttpContext; ???????????try ???????????{ ???????????????var newHttpContext = serviceProvider.GetRequiredService<IHttpContextFactory>().Create(helper.ViewContext.HttpContext.Features); ???????????????if (newHttpContext.Items.ContainsKey(typeof(IUrlHelper))) ???????????????{ ???????????????????newHttpContext.Items.Remove(typeof(IUrlHelper)); ???????????????} ???????????????newHttpContext.Response.Body = new MemoryStream(); ???????????????var actionContext = new ActionContext(newHttpContext, routeData, actionDescriptor); ???????????????actionContextAccessor.ActionContext = actionContext; ???????????????var invoker = serviceProvider.GetRequiredService<IActionInvokerFactory>().CreateInvoker(actionContext); ???????????????await invoker.InvokeAsync(); ???????????????newHttpContext.Response.Body.Position = 0; ???????????????using (var reader = new StreamReader(newHttpContext.Response.Body)) ???????????????{ ???????????????????return new HtmlString(reader.ReadToEnd()); ???????????????} ???????????} ???????????catch (Exception ex) ???????????{ ???????????????return new HtmlString(ex.Message); ???????????} ???????????finally ???????????{ ???????????????actionContextAccessor.ActionContext = originalActionContext; ???????????????httpContextAccessor.HttpContext = originalhttpContext; ???????????????if (helper.ViewContext.HttpContext.Items.ContainsKey(typeof(IUrlHelper))) ???????????????{ ???????????????????helper.ViewContext.HttpContext.Items.Remove(typeof(IUrlHelper)); ???????????????} ???????????} ???????} ???}}
2、 在Startup中的 ConfigureServices 方法添加：
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor();
services.AddSingleton<IActionContextAccessor, ActionContextAccessor>();
（备注：因为net core 默认不将IHttpContextAccessor，IActionContextAccessor 依赖注入，所以需要手动进行依赖注入）
3、在页面中，我们就可以直接用 @Html.Action()方法 直接请求 控制器的方法了。
4、小结：如今微软官方已经提供了 新的 TagHelper、View components 来替代之前的写法。这个教程只适用于对视图层不想做更变的小伙伴使用。如果 是新项目的，还是建议使用 View components!
转自:https://blog.csdn.net/huanghuangtongxue/article/details/78987833
Asp.Net Core 之 @Html.Action 迁移
原文地址：https://www.cnblogs.com/GavinSun/p/9244833.html