首先，现有的三层项目的结构
其中 Repository
public interface IPersonRepository ???{ ????????string Eat(); ???}public class PersonRepository : IPersonRepository ???{ ???????public string Eat() ???????{ ???????????return "吃饭"; ???????} ???}Service
public interface IPersonService ???{ ???????string Eat(); ???} public class PersonService : IPersonService ???{ ??????private ?IPersonRepository _personRespository; ???????//通过构造函数注入 repository ???????public ?PersonService(IPersonRepository personRespository) ???????{ ?????????_personRespository = personRespository; ???????} ???????public string Eat() ???????{ ???????????return ?_personRespository.Eat(); ???????} ???}一、安装Autofac
nuget上安装Autofac
二、替换内置的DI框架
将Startup.cs中的ConfigureServices返回类型改为IServiceProvider，然后新起一个方法RegisterAutofac把创建容器的代码放到其中，然后建一个AutofacConfig 类来存放具体的注入代码，避免
Startup.cs文件代码过多混乱。
public IServiceProvider 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.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1); ???????????return RegisterAutofac(services);//注册Autofac ???????} ???????private IServiceProvider RegisterAutofac(IServiceCollection services) ???????{ ???????????//实例化Autofac容器 ???????????var builder = new ContainerBuilder(); ???????????builder.Populate(services); ???????????//Autofac注册对象 ????????????????????AutofacConfig.RegisterObj(builder); ???????????var Container = builder.Build(); ???????????//第三方IOC接管 core内置DI容器 ????????????return new AutofacServiceProvider(Container); ???????} public class AutofacConfig ???{ ???????public static void RegisterObj(ContainerBuilder builder) ???????{ ???????????//注册Service中的组件,Service中的类要以Service结尾，否则注册失败 ???????????builder.RegisterAssemblyTypes(GetAssemblyByName("WXL.Service")).Where(a => a.Name.EndsWith("Service")).AsImplementedInterfaces(); ???????????//注册Repository中的组件,Repository中的类要以Repository结尾，否则注册失败 ???????????builder.RegisterAssemblyTypes(GetAssemblyByName("WXL.Repository")).Where(a => a.Name.EndsWith("Repository")).AsImplementedInterfaces(); ???????} ???????/// <summary> ???????/// 根据程序集名称获取程序集 ???????/// </summary> ???????/// <param name="AssemblyName">程序集名称</param> ???????/// <returns></returns> ???????public static Assembly GetAssemblyByName(String AssemblyName) ???????{ ???????????return Assembly.Load(AssemblyName); ???????} ???}此时Autofac基本使用已经配好了。
三、测试效果
修改HomeController 实现注入Service
public class HomeController : Controller ???{ ???????private IPersonService _personService; ?????????????//通过构造函数注入Service ???????public HomeController(IPersonService personService) ???????{ ???????????_personService = personService; ???????} ???????public IActionResult Index() ???????{ ???????????ViewBag.eat = _personService.Eat(); ???????????return View(); ???????}}页面结果:
四、一个接口多个实现的情况
比喻我现在在Service 中建三个类，IPayService, WxPayService,AliPayService,其中WxPayService,AliPayService都实现接口IPayService。
public interface IPayService ???{ ???????string Pay(); ???}public class AliPayService : IPayService ???{ ???????public string Pay() ???????{ ???????????return "支付宝支付"; ???????} ???} public class WxPayService : IPayService ???{ ???????public string Pay() ???????{ ???????????return "微信支付"; ???????} ???}先试一下结果,修改HomeController
public class HomeController : Controller ???{ ???????private IPersonService _personService; ???????private IPayService _payService; ?????????????//通过构造函数注入Service ???????public HomeController(IPersonService personService,IPayService payService) ???????{ ???????????_personService = personService; ???????????_payService = payService; ???????} ???????public IActionResult Index() ???????{ ???????????ViewBag.eat = _personService.Eat(); ???????????ViewBag.pay = _payService.Pay(); ???????????return View(); ???????} ???}View
@{ ???ViewData["Title"] = "Home Page";}@ViewBag.eat <br />@ViewBag.pay输出页面:
最后得到的是微信支付，因为两个对象实现一个接口的时候，注册时后面注册的会覆盖前面注册的。如果我想得到支付宝支付要怎么做呢?
我们可以用另外一种注册方式RegisterType，修改注册方式AutofacConfig.cs。
public static void RegisterObj(ContainerBuilder builder) ???????{ ???????????//注册Service中的组件,Service中的类要以Service结尾，否则注册失败 ???????????builder.RegisterAssemblyTypes(GetAssemblyByName("WXL.Service")).Where(a => a.Name.EndsWith("Service")).AsImplementedInterfaces(); ???????????//注册Repository中的组件,Repository中的类要以Repository结尾，否则注册失败 ???????????builder.RegisterAssemblyTypes(GetAssemblyByName("WXL.Repository")).Where(a => a.Name.EndsWith("Repository")).AsImplementedInterfaces(); ???????????//单独注册 ???????????builder.RegisterType<WxPayService>().Named<IPayService>(typeof(WxPayService).Name); ???????????builder.RegisterType<AliPayService>().Named<IPayService>(typeof(AliPayService).Name); ???????} ???????/// <summary> ???????/// 根据程序集名称获取程序集 ???????/// </summary> ???????/// <param name="AssemblyName">程序集名称</param> ???????/// <returns></returns> ???????public static Assembly GetAssemblyByName(String AssemblyName) ???????{ ???????????return Assembly.Load(AssemblyName); ???????}用Named区分两个组件的不同，后面的typeof(WxPayService).Name 是任意字符串，这里直接用这个类名作标识，方便取出来时也是用这个名字，不易忘记。
然后就是取出对应的组件了，取的时候用Autofac的 上下文(IComponentContext) ，修改HomeController
public class HomeController : Controller ???{ ???????private IPersonService _personService; ???????private IPayService _wxPayService; ???????private IPayService _aliPayService; ???????private IComponentContext _componentContext;//Autofac上下文 ???????//通过构造函数注入Service ???????public HomeController(IPersonService personService, IComponentContext componentContext) ???????{ ???????????_personService = personService; ???????????_componentContext = componentContext; ???????????//解释组件 ???????????_wxPayService = componentContext.ResolveNamed<IPayService>(typeof(WxPayService).Name); ???????????_aliPayService =componentContext.ResolveNamed<IPayService>(typeof(AliPayService).Name); ???????} ???????public IActionResult Index() ???????{ ???????????ViewBag.eat = _personService.Eat(); ???????????ViewBag.wxPay = _wxPayService.Pay(); ???????????ViewBag.aliPay = _aliPayService.Pay(); ???????????return View(); ???????} ???}Index View:
@{ ???ViewData["Title"] = "Home Page";}@ViewBag.eat <br />@ViewBag.wxPay <br />@ViewBag.aliPay结果：
完成。
.net core2.1 ?三层中使用Autofac代替原来Ioc
原文地址：https://www.cnblogs.com/wei325/p/9191686.html