概述

ASP.NET Core 支持依賴關系注入 (DI) 軟件設計模式，這是一種在類及其依賴關系之間實現控制反轉 (IoC)?的技術。

默認服務容器是 Microsoft.Extensions.DependencyInjection 。

內置的服務容器一般能滿足簡單的框架和部分消費者應用的需求。?建議使用內置容器，除非你需要的特定功能不受內置容器支持，例如：

屬性注入

基于名稱的注入

子容器

自定義生存期管理

對遲緩初始化的?Func<T>?支持

基于約定的注冊

而大部分情況下，實際項目中往往是比較復雜的，所以可以使用其他第三方IOC容器，如Autofac;

Autofac

Autofac 是.Net世界中最常用的依賴注入框架之一. 相比.Net Core標準的依賴注入庫, 它提供了更多高級特性, 比如動態代理和屬性注入.

優點：?

它是C#語言聯系很緊密，也就是說C#里的很多編程方式都可以為Autofac使用，例如可以用Lambda表達式注冊組件

較低的學習曲線，學習它非常的簡單，只要你理解了IoC和DI的概念以及在何時需要使用它們

XML配置支持

自動裝配

具體使用

1、項目中引用

<PackageReference Include="Autofac" Version="4.9.1" /><PackageReference Include="Autofac.Extensions.DependencyInjection" Version="4.3.1" />

2、準備好類、接口

using System.Collections.Generic;namespace AspNetCoreExample.Services {public interface IValuesService{IEnumerable<string> FindAll();string Find(int id);} } using System.Collections.Generic; using Microsoft.Extensions.Logging;namespace AspNetCoreExample.Services {public class ValuesService : IValuesService{private readonly ILogger<ValuesService> _logger;public ValuesService(ILogger<ValuesService> logger){_logger = logger;}public IEnumerable<string> FindAll(){_logger.LogDebug("{method} called", nameof(FindAll));return new[] { "value1", "value2" };}public string Find(int id){_logger.LogDebug("{method} called with {id}", nameof(Find), id);return $"value{id}";}} }

3、替換掉內置的Ioc

using System; using System.Linq; using Autofac.Extensions.DependencyInjection; using Microsoft.AspNetCore; using Microsoft.AspNetCore.Builder; using Microsoft.AspNetCore.Hosting;namespace AspNetCoreExample {public class Program{public static void Main(string[] args){// The ConfigureServices call here allows for// ConfigureContainer to be supported in Startup with// a strongly-typed ContainerBuilder. If you don't// have the call to AddAutofac here, you won't get// ConfigureContainer support. This also automatically// calls Populate to put services you register during// ConfigureServices into Autofac.var host = WebHost.CreateDefaultBuilder(args).ConfigureServices(services => services.AddAutofac()).UseStartup<Startup>().Build();host.Run();}} }using System; using System.Linq; using Autofac; using Microsoft.AspNetCore.Builder; using Microsoft.AspNetCore.Hosting; using Microsoft.Extensions.Configuration; using Microsoft.Extensions.DependencyInjection;namespace AspNetCoreExample {// ASP.NET Core docs for Autofac are here:// https://autofac.readthedocs.io/en/latest/integration/aspnetcore.htmlpublic class Startup{public Startup(IHostingEnvironment env){var builder = new ConfigurationBuilder().SetBasePath(env.ContentRootPath).AddJsonFile("appsettings.json", optional: true, reloadOnChange: true).AddEnvironmentVariables();this.Configuration = builder.Build();}public IConfigurationRoot Configuration { get; private set; }public void Configure(IApplicationBuilder app){app.UseMvc();}public void ConfigureContainer(ContainerBuilder builder){// Add any Autofac modules or registrations.// This is called AFTER ConfigureServices so things you// register here OVERRIDE things registered in ConfigureServices.//// You must have the call to AddAutofac in the Program.Main// method or this won't be called.builder.RegisterModule(new AutofacModule());}public void ConfigureServices(IServiceCollection services){// Use extensions from libraries to register services in the// collection. These will be automatically added to the// Autofac container.//// Note if you have this method return an IServiceProvider// then ConfigureContainer will not be called.services.AddMvc();}} }

4、注入我們準備好的測試類、接口

using Autofac; using AspNetCoreExample.Services; using Microsoft.Extensions.Logging;namespace AspNetCoreExample {public class AutofacModule : Module{protected override void Load(ContainerBuilder builder){// The generic ILogger<TCategoryName> service was added to the ServiceCollection by ASP.NET Core.// It was then registered with Autofac using the Populate method. All of this starts// with the services.AddAutofac() that happens in Program and registers Autofac// as the service provider.builder.Register(c => new ValuesService(c.Resolve<ILogger<ValuesService>>())).As<IValuesService>().InstancePerLifetimeScope();}} }

5、小試牛刀，用起來

using System.Collections.Generic; using AspNetCoreExample.Services; using Microsoft.AspNetCore.Mvc;namespace AspNetCoreExample.Controllers {/// <summary>/// Simple REST API controller that shows Autofac injecting dependencies./// </summary>/// <seealso cref="Microsoft.AspNetCore.Mvc.Controller" />[Route("api/[controller]")]public class ValuesController : Controller{private readonly IValuesService _valuesService;public ValuesController(IValuesService valuesService){this._valuesService = valuesService;}// GET api/values[HttpGet]public IEnumerable<string> Get(){return this._valuesService.FindAll();}// GET api/values/5[HttpGet("{id}")]public string Get(int id){return this._valuesService.Find(id);}} }

總結

以上是生活随笔為你收集整理的ASP.NET Core 依赖注入-集成 Autofac的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。