1首先引用sessionNuget包

2在startup.cs找到方法ConfigureServices(IServiceCollection services) 注入Session(这个地方是Asp.net Core pipeline):services.AddSession();
接下来我们要告诉Asp.net Core使用内存存储Session数据，在Configure(IApplicationBuilder app,...)中添加代码:app.UseSession();
3在homecontroller中实现

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;

    public IActionResult Index()
        {
            HttpContext.Session.SetString("code", "你好我是session");
            ViewBag.Code = HttpContext.Session.GetString("code");
            return View();
        }

4实现效果