比起 Angular 的依赖注入, core 的相对简单许多, 容易明白
所有 provider 都在 startup 里配置.
public void ConfigureServices(IServiceCollection services){ ???services.Configure<Business>(Configuration.GetSection("business")); ???services.Configure<Configuration.Email>(Configuration.GetSection("email")); ???services.AddEmail(); ???// Razor template ????services.AddSingleton<ICompositeViewEngine, CompositeViewEngine>(); ???services.AddSingleton<IActionContextAccessor, ActionContextAccessor>(); ???// Entity ????services.AddScoped(_ => new DB(Configuration.GetConnectionString("DefaultConnection"))); ???// hangfire ???services.AddHangfire(config => ???????????config.UseSqlServerStorage(Configuration.GetConnectionString("DefaultConnection"))); ???// MVC ???services.Configure<RazorViewEngineOptions>(options => ???{ ???????options.ViewLocationExpanders.Add(new FeatureLocationExpander()); ???}); ???services.AddMvc();}controller 就通过 constructor 来注入就可以了.
private readonly DB db;private ICompositeViewEngine CompositeViewEngine { get; set; }private ActionContext ActionContext { get; set; }private IServiceProvider ServiceProvider { get; set; }private ITempDataProvider TempDataProvider { get; set; }private Configuration.Email EmailConfig { get; set; }public DebugController( ???DB db, ???ICompositeViewEngine compositeViewEngine, ???IActionContextAccessor actionContextAccessor, ???IServiceProvider serviceProvider, ???ITempDataProvider tempDataProvider, ???IOptionsSnapshot<Configuration.Email> emailOptionsAccessor){ ???CompositeViewEngine = compositeViewEngine; ???ActionContext = actionContextAccessor.ActionContext; ???ServiceProvider = serviceProvider; ???TempDataProvider = tempDataProvider; ???EmailConfig = emailOptionsAccessor.Value; ???this.db = db;}provider 有 3 个级别
AddSingleton
AddScoped
AddTransient
单列是说整个 App 用一个实例
Scope 一个 request 一个实例
transient 则是每一个注入一个实例
一个模块一般上会提供好多 Service
那么要让 startup 干净一些的话，我们可以包装起来
就好像这样 services.AddEmail();
做法是开一个扩展方法
namespace Project.Email{ ???public static class ServiceCollectionExtensions ???{ ???????public static IServiceCollection AddEmail( ???????????this IServiceCollection services) ???????{ ???????????services.AddSingleton<ICompositeViewEngine, CompositeViewEngine>(); ???????????services.AddSingleton<IActionContextAccessor, ActionContextAccessor>(); ???????????services.AddScoped<EmailService, EmailService>(); ???????????return services; ???????} ???} ???public class EmailService ???{ ???????public EmailService() ???????{ ???????} ???????public string name { get; set; } = "dada"; ???}}Asp.net core 学习笔记 ( DI 依赖注入 )
原文地址：http://www.cnblogs.com/keatkeat/p/7742543.html