ASP.NET Core 2.0中CookieAuthentication如何使用

public void ConfigureServices(IServiceCollection services){    services.AddCookieAuthentication();    services.AddMvc(options =>    {        var policy = new AuthorizationPolicyBuilder()            .RequireAuthenticatedUser()            .Build();　　　　 // 因为是后台系统，必须登陆以后才能操作        options.Filters.Add(new AuthorizeFilter(policy));    });}

public void Configure(IApplicationBuilder app, IHostingEnvironment env){    if (env.IsDevelopment())    {        app.UseDeveloperExceptionPage();    }    else    {        app.UseExceptionHandler("/Home/Error");    }    app.UseStaticFiles();　　// 使用Authentication中间件    app.UseAuthentication();    app.UseMvc(routes =>    {        routes.MapRoute(            name: "default",            template: "{controller=Home}/{action=Index}/{id?}");    });}

public static class CookieAuthenticationDefaults{    /// <summary>    /// The default value used for CookieAuthenticationOptions.AuthenticationScheme    /// </summary>    public const string AuthenticationScheme = "Cookies";    /// <summary>    /// The prefix used to provide a default CookieAuthenticationOptions.CookieName    /// </summary>    public static readonly string CookiePrefix = ".AspNetCore.";    /// <summary>    /// The default value used by CookieAuthenticationMiddleware for the    /// CookieAuthenticationOptions.LoginPath    /// </summary>    public static readonly PathString LoginPath = new PathString("/Account/Login");    /// <summary>    /// The default value used by CookieAuthenticationMiddleware for the    /// CookieAuthenticationOptions.LogoutPath    /// </summary>    public static readonly PathString LogoutPath = new PathString("/Account/Logout");    /// <summary>    /// The default value used by CookieAuthenticationMiddleware for the    /// CookieAuthenticationOptions.AccessDeniedPath    /// </summary>    public static readonly PathString AccessDeniedPath = new PathString("/Account/AccessDenied");    /// <summary>    /// The default value of the CookieAuthenticationOptions.ReturnUrlParameter    /// </summary>    public static readonly string ReturnUrlParameter = "ReturnUrl";}

public async Task<IActionResult> LoginDo(){　　var user = new ClaimsPrincipal(new ClaimsIdentity(new[] { new Claim(ClaimTypes.Name, "bob") }, CookieAuthenticationDefaults.AuthenticationScheme));　　await HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, user, new AuthenticationProperties　　{　　　　IsPersistent = true,　　　　ExpiresUtc = DateTimeOffset.Now.Add(TimeSpan.FromDays(180))　　});　　return Redirect("/");}

public async Task<IActionResult> Logout(){    await HttpContext.SignOutAsync(CookieAuthenticationDefaults.AuthenticationScheme);    return Redirect("/");}