感谢@Kirk指出我不应该认为它是.NET Core 2.0！
程序和启动类
.NET Core 2.x
您不需要
IConfiguration在
Startup构造函数中新建。它的实现将由DI系统注入。
// Program.cspublic class Program{ public static void Main(string[] args) { BuildWebHost(args).Run(); } public static IWebHost BuildWebHost(string[] args) => WebHost.CreateDefaultBuilder(args) .UseStartup<Startup>() .Build(); }// Startup.cspublic class Startup{ public IHostingEnvironment HostingEnvironment { get; private set; } public IConfiguration Configuration { get; private set; } public Startup(IConfiguration configuration, IHostingEnvironment env) { this.HostingEnvironment = env; this.Configuration = configuration; }}.NET Core 1.x
您需要告诉
Startup加载appsettings文件。
// Program.cspublic class Program{ public static void Main(string[] args) { var host = new WebHostBuilder() .UseKestrel() .UseContentRoot(Directory.GetCurrentDirectory()) .UseIISIntegration() .UseStartup<Startup>() .UseApplicationInsights() .Build(); host.Run(); }}//Startup.cspublic class Startup{ public IConfigurationRoot Configuration { get; private set; } public Startup(IHostingEnvironment env) { var builder = new ConfigurationBuilder() .SetbasePath(env.ContentRootPath) .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true) .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true) .AddEnvironmentVariables(); this.Configuration = builder.Build(); } ...}获得价值
您可以通过多种方法从应用程序设置中获取配置的值：
- 简单的使用方法
ConfigurationBuilder.GetValue<T>
- 使用 选项模式
假设您的
appsettings.json样子是这样的：
{ "ConnectionStrings": { ... }, "AppIdentitySettings": { "User": { "RequireUniqueEmail": true }, "Password": { "RequiredLength": 6, "RequireLowercase": true, "RequireUppercase": true, "RequireDigit": true, "RequireNonAlphanumeric": true }, "Lockout": { "AllowedForNewUsers": true, "DefaultLockoutTimeSpanInMins": 30, "MaxFailedAccessAttempts": 5 } }, "Recaptcha": { ... }, ...}简单方法
您可以将整个配置注入到控制器/类的构造函数中（通过
IConfiguration），并使用指定的键获取所需的值：
public class AccountController : Controller{ private readonly IConfiguration _config; public AccountController(IConfiguration config) { _config = config; } [AllowAnonymous] public IActionResult ResetPassword(int userId, string pre) { var vm = new ResetPasswordViewModel { PasswordRequiredLength = _config.GetValue<int>( "AppIdentitySettings:Password:RequiredLength"), RequireUppercase = _config.GetValue<bool>( "AppIdentitySettings:Password:RequireUppercase") }; return View(vm); }}选项模式
的
ConfigurationBuilder.GetValue<T>，如果你只需要从应用程序设置一个或两个值的伟大工程。但是，如果您想从应用程序设置中获取多个值，或者不想在多个位置对这些键字符串进行硬编码，则使用
Options Pattern 可能会更容易。选项模式使用类来表示层次结构/结构。
要使用选项模式：
- 定义代表结构的类
- 注册那些类绑定到的配置实例
- 注入
IOptions<T>
要获取值的控制器/类的构造函数
1.定义配置类以表示结构
您可以定义具有 需要与 您的应用程序设置 中 的键 完全匹配 的属性的类。类的名称不必与应用程序设置中的部分名称匹配：
public class AppIdentitySettings{ public UserSettings User { get; set; } public PasswordSettings Password { get; set; } public LockoutSettings Lockout { get; set; }}public class UserSettings{ public bool RequireUniqueEmail { get; set; }}public class PasswordSettings{ public int RequiredLength { get; set; } public bool RequireLowercase { get; set; } public bool RequireUppercase { get; set; } public bool RequireDigit { get; set; } public bool RequireNonAlphanumeric { get; set; }}public class LockoutSettings{ public bool AllowedForNewUsers { get; set; } public int DefaultLockoutTimeSpanInMins { get; set; } public int MaxFailedAccessAttempts { get; set; }}2.注册配置实例
然后，您需要
ConfigureServices()在启动时注册此配置实例：
using Microsoft.Extensions.Configuration;using Microsoft.Extensions.DependencyInjection;...namespace DL.SO.UI.Web{ public class Startup { ... public void ConfigureServices(IServiceCollection services) { ... var identitySettingsSection = _configuration.GetSection("AppIdentitySettings"); services.Configure<AppIdentitySettings>(identitySettingsSection); ... } ... }}3.注入IOptions
最后，在要获取值的控制器/类上，需要
IOptions<AppIdentitySettings>通过构造函数注入：
public class AccountController : Controller{ private readonly AppIdentitySettings _appIdentitySettings; public AccountController(IOptions<AppIdentitySettings> appIdentitySettingsAccessor) { _appIdentitySettings = appIdentitySettingsAccessor.Value; } [AllowAnonymous] public IActionResult ResetPassword(int userId, string pre) { var vm = new ResetPasswordViewModel { PasswordRequiredLength = _appIdentitySettings.Password.RequiredLength, RequireUppercase = _appIdentitySettings.Password.RequireUppercase }; return View(vm); }}
