在asp.net Core中，实现验证和授权是一个非常基本的任务。使用asp.net Core身份验证，我们可以非常轻松地对应用程序实施控制访问机制。本文将介绍如何在ASP.NET Core应用程序中使用身份验证来登录用户并将其重定向到Admin页面。

首先，我们需要在ASP.NET Core应用程序中安装以下NuGet包：

• Microsoft.AspNetCore.Authentication.Cookies
• Microsoft.AspNetCore.Identity.EntityFrameworkCore
• Microsoft.EntityFrameworkCore.Design

接下来，在Startup.cs文件中进行以下配置：

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext(options => 
    options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    services.AddIdentity()
        .AddEntityFrameworkStores()
        .AddDefaultTokenProviders();

    services.ConfigureApplicationCookie(options =>
    {
        // Cookie settings  
        options.Cookie.HttpOnly = true;
        options.ExpireTimeSpan = TimeSpan.FromMinutes(30);
        options.LoginPath = "/Account/Login"; // 自定义登录页面路径
        options.AccessDeniedPath = "/Account/AccessDenied"; // 自定义访问被拒绝页面路径
        options.SlidingExpiration = true;
    });
 
    services.AddMvc();
}

在Configure方法中添加以下代码：

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.UseAuthentication();

    app.UseMvc(routes =>
    {
        routes.MapRoute(
        name: "default",
        template: "{controller=Home}/{action=Index}/{id?}");
    });
}

接下来，在AccountController中添加以下代码:

public class AccountController : Controller
{
    private readonly UserManager _userManager;
    private readonly SignInManager _signInManager;

    public AccountController(
        UserManager userManager,
        SignInManager signInManager)
    {
        _userManager = userManager;
        _signInManager = signInManager;
    }

    public IActionResult Login()
    {
        return View();
    }

    [HttpPost]
    public async Task Login(LoginViewModel model, string returnUrl = null)
    {
        ViewData["ReturnUrl"] = returnUrl;
        if (ModelState.IsValid)
        {
            var result = await _signInManager.PasswordSignInAsync(model.Email, model.Password, model.RememberMe, lockoutOnFailure: false);
            if (result.Succeeded)
            {
                return RedirectToLocal(returnUrl);
            }
            if (result.RequiresTwoFactor)
            {
                return RedirectToAction(nameof(LoginWith2fa), new { returnUrl, model.RememberMe });