今天我们再来了解一个很重要的接口IAuthenticationService的实现类AuthenticationService：
public class AuthenticationService : IAuthenticationService
{
public AuthenticationService(IAuthenticationSchemeProvider schemes, IAuthenticationHandlerProvider handlers, IClaimsTransformation transform)
{
Schemes = schemes;
Handlers = handlers;
Transform = transform;
} public IAuthenticationSchemeProvider Schemes { get; }
public IAuthenticationHandlerProvider Handlers { get; }
public IClaimsTransformation Transform { get; } public virtual async Task<AuthenticateResult> AuthenticateAsync(HttpContext context, string scheme)
{
if (scheme == null)
{
var defaultScheme = await Schemes.GetDefaultAuthenticateSchemeAsync();
scheme = defaultScheme?.Name;
if (scheme == null)
{
throw new InvalidOperationException($"No authenticationScheme was specified, and there was no DefaultAuthenticateScheme found.");
}
} var handler = await Handlers.GetHandlerAsync(context, scheme);
if (handler == null)
{
throw await CreateMissingHandlerException(scheme);
} var result = await handler.AuthenticateAsync();
if (result != null && result.Succeeded)
{
var transformed = await Transform.TransformAsync(result.Principal);
return AuthenticateResult.Success(new AuthenticationTicket(transformed, result.Properties, result.Ticket.AuthenticationScheme));
}
return result;
} /// <summary>
/// Challenge the specified authentication scheme.
/// </summary>
/// <param name="context">The <see cref="HttpContext"/>.</param>
/// <param name="scheme">The name of the authentication scheme.</param>
/// <param name="properties">The <see cref="AuthenticationProperties"/>.</param>
/// <returns>A task.</returns>
public virtual async Task ChallengeAsync(HttpContext context, string scheme, AuthenticationProperties properties)
{
if (scheme == null)
{
var defaultChallengeScheme = await Schemes.GetDefaultChallengeSchemeAsync();
scheme = defaultChallengeScheme?.Name;
if (scheme == null)
{
throw new InvalidOperationException($"No authenticationScheme was specified, and there was no DefaultChallengeScheme found.");
}
} var handler = await Handlers.GetHandlerAsync(context, scheme);
if (handler == null)
{
throw await CreateMissingHandlerException(scheme);
} await handler.ChallengeAsync(properties);
} /// <summary>
/// Forbid the specified authentication scheme.
/// </summary>
public virtual async Task ForbidAsync(HttpContext context, string scheme, AuthenticationProperties properties)
{
if (scheme == null)
{
var defaultForbidScheme = await Schemes.GetDefaultForbidSchemeAsync();
scheme = defaultForbidScheme?.Name;
...
} var handler = await Handlers.GetHandlerAsync(context, scheme);
...await handler.ForbidAsync(properties);
} /// <summary>
/// Sign a principal in for the specified authentication scheme.
/// </summary>
public virtual async Task SignInAsync(HttpContext context, string scheme, ClaimsPrincipal principal, AuthenticationProperties properties)
{
...
if (scheme == null)
{
var defaultScheme = await Schemes.GetDefaultSignInSchemeAsync();
scheme = defaultScheme?.Name;
...
} var handler = await Handlers.GetHandlerAsync(context, scheme);
...
var signInHandler = handler as IAuthenticationSignInHandler;
...
await signInHandler.SignInAsync(principal, properties);
} /// <summary>
/// Sign out the specified authentication scheme.
/// </summary>
public virtual async Task SignOutAsync(HttpContext context, string scheme, AuthenticationProperties properties)
{
if (scheme == null)
{
var defaultScheme = await Schemes.GetDefaultSignOutSchemeAsync();
scheme = defaultScheme?.Name;
if (scheme == null)
{
throw new InvalidOperationException($"No authenticationScheme was specified, and there was no DefaultSignOutScheme found.");
}
} var handler = await Handlers.GetHandlerAsync(context, scheme);
if (handler == null)
{
throw await CreateMissingSignOutHandlerException(scheme);
} var signOutHandler = handler as IAuthenticationSignOutHandler;
if (signOutHandler == null)
{
throw await CreateMismatchedSignOutHandlerException(scheme, handler);
} await signOutHandler.SignOutAsync(properties);
}
}
该类通过构造方法，将我们前两篇中讲到了IAuthenticationSchemeProvider和IAuthenticationHandlerProvider注入了进来，第三个参数不是很重要就飘过了。接下来我们看看它的这几个方法AuthenticateAsync、ChallengeAsync、ForbidAsync、SignInAsync和SignOutAsync等方法，他们的套路几乎都一样的，通过注入进来的两个接口的实例，最终获得到IAuthenticationHandler接口实例，并调用同名方法。
关于IAuthenticationService、IAuthenticationHandlerProvider和IAuthenticationSchemeProvider我们又是什么时候注入到服务容器里去的呢？它是在AuthenticationCoreServiceCollectionExtensions这个静态类中的AddAuthenticationCore扩展方法注入到容器中的，还有AuthenticationOptions也是在这里注入到依赖注入系统的容器中的：
public static class AuthenticationCoreServiceCollectionExtensions
{
public static IServiceCollection AddAuthenticationCore(this IServiceCollection services)
{
...
services.TryAddScoped<IAuthenticationService, AuthenticationService>();
services.TryAddSingleton<IClaimsTransformation, NoopClaimsTransformation>(); // Can be replaced with scoped ones that use DbContext
services.TryAddScoped<IAuthenticationHandlerProvider, AuthenticationHandlerProvider>();
services.TryAddSingleton<IAuthenticationSchemeProvider, AuthenticationSchemeProvider>();
return services;
} public static IServiceCollection AddAuthenticationCore(this IServiceCollection services, Action<AuthenticationOptions> configureOptions) {
...
services.AddAuthenticationCore();
services.Configure(configureOptions);
return services;
}
}
该扩展方法是在Startup的ConfigureServices方法调用的。这个就不贴代码了。
注入完以后呢？怎么使用呢？为了方便使用，aspnetcore为我们在外面又裹了一层，那就是AuthenticationHttpContextExtensions为HttpContext添加的扩展方法。我们可以在Controller如下调用：
public class HomeController : Controller
{
public IActionResult Index()
{
var result = HttpContext.AuthenticateAsync();
return View(result.Result);
}
}
至此认证相关的核心元素介绍完成，本篇到此结束。