1、通过nuget/修改project.json引用

2、引用存储session的媒介，如内存、数据库、redis等

"Microsoft.AspNetCore.Session": "1.1.0-*",

"Microsoft.Extensions.Caching.Memory": "1.1.0-*",

"Microsoft.Extensions.Caching.Redis": "1.1.0-*",

"Microsoft.Extensions.Caching.SqlServer": "1.1.0-*",

3、修改startup.cs

   public void ConfigureServices(IServiceCollection services)
    {
        services.AddDistributedMemoryCache();
        services.AddSession();
        services.AddMvc();
    }
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        app.UseSession();

4 其他地方使用
Context.Session.GetString("UserName")

视图中使用
string str = Microsoft.AspNetCore.Http.SessionExtensions.GetString(Context.Session,"User");