一. Identity 介绍
ASP.NET Core Identity是一个会员系统，可为ASP.NET Core应用程序添加登录功能。可以使用SQL Server数据库配置身份以存储用户名，密码和配置文件数据。或者，可以使用另一个持久性存储，例如，Azure表存储。下面学习如何使用Identity注册，登录以及基架标识。
1.1 Identity搭建演示
下面使用vs 2017来演示：
1.选择“文件” > “新建” > “项目”。
2.选择“ASP.NET Core Web应用程序”。 将项目命名WebAppIdentityDemo具有项目下载相同的命名空间。 单击 “确定”。
3.选择 ASP.NET Core Web MVC应用程序，然后选择更改身份验证。
4.选择单个用户帐户然后单击确定。
生成的项目包含了Identity会员系统，目录结构如下所示，生成后的目录结构有疑惑，怎么没看见Identity会员系统相关的model, Controller,cshtml等文件，继续往下了解。
(1) 修改连接字符串
找到appsettings.json文件，修改ConnectionStrings的数据库连接字符串, 默认是连接本机sql server数据库，我改成了连接远程数据库。
"ConnectionStrings": { ???"DefaultConnection": "Data Source = 172.168.16.75;Initial Catalog =IdentityDB; User ID = hsr;Password =js*2015;" ?},(2) 基于生成的迁移代码，同步到数据库
PM> Update-Database
(3) 配置Identity服务
???????public void ConfigureServices(IServiceCollection services) ???????{ ???????????services.Configure<CookiePolicyOptions>(options => ???????????{ ???????????????// This lambda determines whether user consent for non-essential cookies is needed for a given request. ???????????????options.CheckConsentNeeded = context => true; ???????????????options.MinimumSameSitePolicy = SameSiteMode.None; ???????????}); ???????????services.AddDbContext<ApplicationDbContext>(options => ???????????????options.UseSqlServer( ???????????????????Configuration.GetConnectionString("DefaultConnection")));
???????????services.AddDefaultIdentity<IdentityUser>() ???????????????.AddDefaultUI(UIFramework.Bootstrap4) ???????????????.AddEntityFrameworkStores<ApplicationDbContext>(); ???????????services.Configure<IdentityOptions>(options => ???????????{ ???????????????// Password settings. ???????????????options.Password.RequireDigit = true; ???????????????options.Password.RequireLowercase = true; ???????????????options.Password.RequireNonAlphanumeric = true; ???????????????options.Password.RequireUppercase = true; ???????????????options.Password.RequiredLength = 6; ???????????????options.Password.RequiredUniqueChars = 1; ???????????????// Lockout settings. ???????????????options.Lockout.DefaultLockoutTimeSpan = TimeSpan.FromMinutes(5); ???????????????options.Lockout.MaxFailedAccessAttempts = 5; ???????????????options.Lockout.AllowedForNewUsers = true; ???????????????// User settings. ???????????????options.User.AllowedUserNameCharacters = ???????????????"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._@+"; ???????????????options.User.RequireUniqueEmail = false; ???????????}); ???????????services.ConfigureApplicationCookie(options => ???????????{ ???????????????// Cookie settings ???????????????options.Cookie.HttpOnly = true; ???????????????options.ExpireTimeSpan = TimeSpan.FromMinutes(5); ???????????????options.LoginPath = "/Identity/Account/Login"; ???????????????options.AccessDeniedPath = "/Identity/Account/AccessDenied"; ???????????????options.SlidingExpiration = true; ???????????}); ???????????services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2); ???????}(4) 确认调用UseAuthentication中间件
public void Configure(IApplicationBuilder app, IHostingEnvironment env){ ???if (env.IsDevelopment()) ???{ ???????app.UseDeveloperExceptionPage(); ???????app.UseDatabaseErrorPage(); ???} ???else ???{ ???????app.UseExceptionHandler("/Error"); ???????app.UseHsts(); ???} ???app.UseHttpsRedirection(); ???app.UseStaticFiles(); ???app.UseCookiePolicy(); ???app.UseAuthentication(); ???app.UseMvc();}(5) 启动程序，首页提供了注册,登录的链接
注册成功后/Identity/Account/Register，在数据库中AspNetUsers表会新增一条数据(密码：Asp.netCore123)。注册成功后，说明数据库连接没有问题，会跳到登录页Identity/Account/Login
虽然没有看到Identity会员系统相关文件，其实已经内置由Razor类库提供。Identity Razor类库使用该Identity Areas公开端点。例如：
/Identity/Account/Login
/Identity/Account/Logout
/Identity/Account/Manage
二. 基架标识(Scaffold Identity )
ASP.NET Core 2.1 及更高版本提供了ASP.NET Core Identity作为Razor 类库。 包含Identity的应用程序可以应用基架，来有选择地添加包含在Identity Razor 类库 (RCL) 的源代码。 建议生成源代码，以便修改代码和更改行为(根据开发需求扩展Identity)。 例如，可以指示基架生成在注册过程中使用的代码。 生成的代码优先于标识 RCL 中的相同代码。 若要获取的用户界面的完全控制，并且使用默认 RCL,等下参考2.2。
2.1 使用Scaffold Identity 授权到MVC 项目
1.从解决方案资源管理器，右键单击该项目 >添加 > 新基架项。
2.从左窗格添加基架对话框中，选择标识 > 添加。
3.在中ADD 标识添加对话框中，选择所需的选项。
下面使用现有的数据上下文，选择所有文件，以便后面重写,如下所示。
生成需要重写的文件后，如下所示(可以比对上图1.1的Areas目录)，注意生成的是razor page 文件，不是MVC视图控制器。之前上面的疑惑解除了。
2.2 创建完整的Identity UI 源
上面2.1中运行Scaffold Identity，保持了对Identity UI的完全控制。以下突出显示的代码显示默认Identity UI 替换Identity在 ASP.NET Core 2.1 web 应用的更改。 需要执行此操作以具有完全控制权限的Identity UI。
???public void ConfigureServices(IServiceCollection services) ???????{ ???????????services.Configure<CookiePolicyOptions>(options => ???????????{ ???????????????// This lambda determines whether user consent for non-essential cookies is needed for a given request. ???????????????options.CheckConsentNeeded = context => true; ???????????????options.MinimumSameSitePolicy = SameSiteMode.None; ???????????}); ???????????services.AddDbContext<ApplicationDbContext>(options => ???????????????options.UseSqlServer( ???????????????????Configuration.GetConnectionString("DefaultConnection"))); ???????????services.AddIdentity<IdentityUser, IdentityRole>() ???????????//services.AddDefaultIdentity<IdentityUser>() ???????????????.AddDefaultUI(UIFramework.Bootstrap4) ???????????????.AddEntityFrameworkStores<ApplicationDbContext>(); ???????????services.Configure<IdentityOptions>(options => ???????????{ ???????????????// Password settings. ???????????????options.Password.RequireDigit = true; ???????????????options.Password.RequireLowercase = true; ???????????????options.Password.RequireNonAlphanumeric = true; ???????????????options.Password.RequireUppercase = true; ???????????????options.Password.RequiredLength = 6; ???????????????options.Password.RequiredUniqueChars = 1; ???????????????// Lockout settings. ???????????????options.Lockout.DefaultLockoutTimeSpan = TimeSpan.FromMinutes(5); ???????????????options.Lockout.MaxFailedAccessAttempts = 5; ???????????????options.Lockout.AllowedForNewUsers = true; ???????????????// User settings. ???????????????options.User.AllowedUserNameCharacters = ???????????????"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-._@+"; ???????????????options.User.RequireUniqueEmail = false; ???????????}); ???????????//services.ConfigureApplicationCookie(options => ???????????//{ ???????????// ???// Cookie settings ???????????// ???options.Cookie.HttpOnly = true; ???????????// ???options.ExpireTimeSpan = TimeSpan.FromMinutes(5); ???????????// ???options.LoginPath = "/Identity/Account/Login"; ???????????// ???options.AccessDeniedPath = "/Identity/Account/AccessDenied"; ???????????// ???options.SlidingExpiration = true; ???????????//}); ???????????services.ConfigureApplicationCookie(options => ???????????{ ???????????????// Cookie settings ???????????????options.Cookie.HttpOnly = true; ???????????????options.ExpireTimeSpan = TimeSpan.FromMinutes(5); ???????????????options.LoginPath = $"/Identity/Account/Login"; ???????????????options.LogoutPath = $"/Identity/Account/Logout"; ???????????????options.AccessDeniedPath = $"/Identity/Account/AccessDenied"; ???????????}); ???????????// services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2); ???????????services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1) ???????????????.AddRazorPagesOptions(options => ???????????????{ ???????????????????options.AllowAreas = true; ???????????????????options.Conventions.AuthorizeAreaFolder("Identity", "/Account/Manage"); ???????????????????options.Conventions.AuthorizeAreaPage("Identity", "/Account/Logout"); ???????????????}); ???????}选择修改Login.cshtml文件，在里面随变加点标记xxxx， 运行显示成功，以后就可以自定义样式布局和扩展权限功能。
参考文献
ASP.NET Core 上的Identity简介
ASP.NET Core 项目中的scaffold-identity
asp.net core系列 46 Identity介绍
原文地址：https://www.cnblogs.com/MrHSR/p/10572462.html