Autofac详解

零、文章目录

一、Autofac详解

1、概述

• Autofac是第三方IOC容器，是当前最流行的IOC容器。
• 功能强大，比asp.netcore内置容器强大得多，支持属性注入和方法注入，支持AOP。
• 官网地址：http://autofac.org/
• 源码下载地址：https://github.com/autofac/Autofac

2、快速开始

（1）Nuget引入程序包

Autofac   基于版本6.3演示，Net5

（2）容器创建对象

//创建一个容器建造者
ContainerBuilder containerBuilder = new ContainerBuilder();
//注册普通类
containerBuilder.RegisterType<Honer>();
//build一下，得到一个容器
IContainer container = containerBuilder.Build();
//可以基于容器来获取对象的实例
Honer phone = container.Resolve<Honer>();

3、注册的类型

（1）注册普通类

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>();
IContainer container = containerBuilder.Build();
Honer phone = container.Resolve<Honer>();

（2）注册抽象与实现

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>();
IContainer container = containerBuilder.Build();
IPhone phone = container.Resolve<IPhone>();

（3）注册程序集

• RegisterAssemblyTypes(程序集数组)，程序集必须是public的
• AsImplementedInterfaces()：表示注册的类型，以接口的方式注册
• PropertiesAutowired()：支持属性注入
• Where：满足条件类型注册

var basePath = AppContext.BaseDirectory;
var dll = Path.Combine(basePath, "MyAutofac.dll");
ContainerBuilder containerBuilder = new ContainerBuilder();
var assemblysServices = Assembly.LoadFrom(dll);
containerBuilder.RegisterAssemblyTypes(assemblysServices)
    .Where(t => !t.Name.EndsWith("XXX"))
    .AsImplementedInterfaces()
    .PropertiesAutowired();                        
IContainer container = containerBuilder.Build();
ITeacher teacher = container.Resolve<ITeacher>();

4、三种注入方式

（1）构造函数注入

默认支持，无法用特性进行筛选，默认选参数最多的构造函数进行注入

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>();
containerBuilder.RegisterType<Teacher>().As<ITeacher>();
containerBuilder.RegisterType<Student>().As<IStudent>();
IContainer container = containerBuilder.Build();
ITeacher teacher = container.Resolve<ITeacher>();

（2）全部属性注入

关键词PropertiesAutowired，这个对象所有属性全部注入

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>();
containerBuilder.RegisterType<Teacher>().As<ITeacher>().PropertiesAutowired();
containerBuilder.RegisterType<Student>().As<IStudent>();
IContainer container = containerBuilder.Build();
ITeacher teacher = container.Resolve<ITeacher>();

（3）标记特性的属性注入

关键词PropertiesAutowired，定义特性选择器CustomPropertySelector

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>();
containerBuilder.RegisterType<Teacher>().As<ITeacher>().PropertiesAutowired(new CustomPropertySelector());
containerBuilder.RegisterType<Student>().As<IStudent>();
IContainer container = containerBuilder.Build();
ITeacher teacher = container.Resolve<ITeacher>();

public class CustomPropertySelector : IPropertySelector
{
    public bool InjectProperty(PropertyInfo propertyInfo, object instance)
    {
        var flag = propertyInfo.CustomAttributes.Any(it => it.AttributeType == typeof(SelectPropAttribute));
        return flag;
    }
}

（4）方法注入

关键词OnActivated，指定调用方法

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>();
containerBuilder.RegisterType<Teacher>().As<ITeacher>()
    .OnActivated(p =>
    {
        p.Instance.SetStudent1(p.Context.Resolve<IStudent>());
    });
containerBuilder.RegisterType<Student>().As<IStudent>();
IContainer container = containerBuilder.Build();
ITeacher teacher = container.Resolve<ITeacher>();

5、对象生命周期

（1）瞬时生命周期

每次获取都是全新的实例，关键词InstancePerDependency，默认的生命周期

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>().InstancePerDependency();
IContainer container = containerBuilder.Build();
IPhone phone1 = container.Resolve<IPhone>();
IPhone phone2 = container.Resolve<IPhone>();
bool isflg1 = object.ReferenceEquals(phone1, phone2);
Console.WriteLine($"InstancePerDependency：phone1==phone2=>{isflg1}");

InstancePerDependency：phone1==phone2=>False

（2）单例生命周期

同一个进程内都是同一个实例，关键词SingleInstance

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>().SingleInstance();
IContainer container = containerBuilder.Build();
IPhone phone1 = container.Resolve<IPhone>();
IPhone phone2 = container.Resolve<IPhone>();
bool isflg1 = object.ReferenceEquals(phone1, phone2);
Console.WriteLine($"SingleInstance：phone1==phone2=>{isflg1}");
using (var scope = container.BeginLifetimeScope())
{
    IPhone phone3 = scope.Resolve<IPhone>();
    IPhone phone4 = scope.Resolve<IPhone>();
    bool isflg2 = object.ReferenceEquals(phone3, phone4);
    Console.WriteLine($"SingleInstance：phone3==phone4=>{isflg2}");
    bool isflg3 = object.ReferenceEquals(phone1, phone3);
    Console.WriteLine($"SingleInstance：phone1==phone3=>{isflg3}");
}

SingleInstance：phone1==phone2=>True
SingleInstance：phone3==phone4=>True
SingleInstance：phone1==phone3=>True

（3）作用域生命周期

同一个作用域内都是同一个实例，关键词InstancePerLifetimeScope

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>().InstancePerLifetimeScope();
IContainer container = containerBuilder.Build();
IPhone phone1 = container.Resolve<IPhone>();
IPhone phone2 = container.Resolve<IPhone>();
bool isflg1 = object.ReferenceEquals(phone1, phone2);
Console.WriteLine($"InstancePerLifetimeScope：phone1==phone2=>{isflg1}");
IPhone phone3 = null;
IPhone phone4 = null;
using (var scope = container.BeginLifetimeScope())
{
    phone3 = scope.Resolve<IPhone>();
    phone4 = scope.Resolve<IPhone>();
    bool isflg2 = object.ReferenceEquals(phone3, phone4);
    Console.WriteLine($"InstancePerLifetimeScope：phone3==phone4=>{isflg2}");
    bool isflg3 = object.ReferenceEquals(phone1, phone3);
    Console.WriteLine($"InstancePerLifetimeScope：phone1==phone3=>{isflg3}");
}
IPhone phone5 = null;
IPhone phone6 = null;
using (var scope = container.BeginLifetimeScope())
{
    phone5 = scope.Resolve<IPhone>();
    phone6 = scope.Resolve<IPhone>();
    bool isflg2 = object.ReferenceEquals(phone5, phone6);
    Console.WriteLine($"InstancePerLifetimeScope：phone5==phone6=>{isflg2}");
    bool isflg3 = object.ReferenceEquals(phone1, phone5);
    Console.WriteLine($"InstancePerLifetimeScope：phone1==phone5=>{isflg3}");
}
bool isflg4 = object.ReferenceEquals(phone3, phone5);
Console.WriteLine($"InstancePerLifetimeScope：phone3==phone5=>{isflg4}");

InstancePerLifetimeScope：phone1==phone2=>True
InstancePerLifetimeScope：phone3==phone4=>True
InstancePerLifetimeScope：phone1==phone3=>False
InstancePerLifetimeScope：phone5==phone6=>True
InstancePerLifetimeScope：phone1==phone5=>False
InstancePerLifetimeScope：phone3==phone5=>False

（4）作用域范围生命周期

在作用域范围外无法创建实例，在作用域范围里面，同一个作用域下面的对象是同一个，关键词InstancePerMatchingLifetimeScope

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>().InstancePerMatchingLifetimeScope("scope1", "scope2");
IContainer container = containerBuilder.Build();
IPhone phone1 = null;
IPhone phone2 = null;
using (var scope = container.BeginLifetimeScope("scope1"))
{
    phone1 = scope.Resolve<IPhone>();
    phone2 = scope.Resolve<IPhone>();
    bool isflg1 = object.ReferenceEquals(phone1, phone2);
    Console.WriteLine($"InstancePerMatchingLifetimeScope：phone1==phone2=>{isflg1}");
}
IPhone phone3 = null;
using (var scope = container.BeginLifetimeScope("scope2"))
{
    phone3 = scope.Resolve<IPhone>();
}                   
IPhone phone4 = null;
using (var scope = container.BeginLifetimeScope("scope2"))
{                        
    phone4 = scope.Resolve<IPhone>();
}
bool isflg2 = object.ReferenceEquals(phone3, phone4);
Console.WriteLine($"InstancePerMatchingLifetimeScope：phone3==phone4=>{isflg2}");
bool isflg3 = object.ReferenceEquals(phone1, phone3);
Console.WriteLine($"InstancePerMatchingLifetimeScope：phone1==phone3=>{isflg3}");

InstancePerMatchingLifetimeScope：phone1==phone2=>True
InstancePerMatchingLifetimeScope：phone3==phone4=>False
InstancePerMatchingLifetimeScope：phone1==phone3=>False

（5）一次请求同一个对象

关键词InstancePerRequest，只能在web项目中调试，控制台报错

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>().InstancePerRequest();
IContainer container = containerBuilder.Build();
IPhone phone1 = container.Resolve<IPhone>();
IPhone phone2 = container.Resolve<IPhone>();
bool isflg1 = object.ReferenceEquals(phone1, phone2);
Console.WriteLine($"InstancePerRequest：phone1==phone2=>{isflg1}");

6、支持配置文件注册

（1）nuget引入程序集

Autofac
Autofac.Configuration
Microsoft.Extensions.Configuration.Json

（2）配置文件autofac.json，属性->始终复制

{
    
  "components": [
    {
    
      //实现
      "type": "Net5.IOC.Honer,Net5.IOC",
      //抽象
      "services": [
        {
    
          "type": "Net5.IOC.IPhone,Net5.IOC"
        }
      ],
      //生命周期
      "instanceScope": "single-instance",
      //属性注入 
      "injectProperties": true
    }
  ]
}

（3）通过配置文件注册创建对象

ContainerBuilder containerBuilder = new ContainerBuilder();
IConfigurationBuilder config = new ConfigurationBuilder();
IConfigurationSource autofacJsonConfigSource = new JsonConfigurationSource()
{
    Path = "Autofac/autofac.json",
    Optional = false,//boolean,默认就是false,可不写
    ReloadOnChange = true,//同上
};
config.Add(autofacJsonConfigSource);
ConfigurationModule module = new ConfigurationModule(config.Build());
containerBuilder.RegisterModule(module);
IContainer container = containerBuilder.Build();
IPhone phone1 = container.Resolve<IPhone>();
IPhone phone2 = container.Resolve<IPhone>();
bool isflg1 = object.ReferenceEquals(phone1, phone2);
Console.WriteLine($"配置文件注册：phone1==phone2=>{isflg1}");

（4）运行结果

配置文件注册：phone1==phone2=>True

7、支持AOP切面编程

可以在不修改方法的前提下，在方法前后添加公共逻辑，日志，异常，缓存等

（1）nuget引入程序集

Castle.Core
Autofac.Extras.DynamicProxy

（2）自定义一个切面类实现IInterceptor接口

public class CustomInterceptor : IInterceptor
{
    public void Intercept(IInvocation invocation)
    {
        Console.WriteLine("方法执行前。。。");
        //执行当前方法
        invocation.Proceed();
        Console.WriteLine("方法执行后。。。");
    }
}

（3）在抽象/实现类上添加特性标记

[Intercept(typeof(CustomInterceptor))]
public interface IPhone
{
    string ShowName();
}
//实现类虚方法
public class Honer : IPhone
{
    public virtual string ShowName()
    {
        Console.WriteLine("Honer");
        return "Honer";
    }
}

（4）在容器中注册关系创建对象

• EnableInterfaceInterceptors + 特性标记在抽象上，所有实现类都支持AOP
• EnableInterfaceInterceptors + 特性标记到实现类上，标记的类就支持AOP
• EnableClassInterceptors，要支持AOP的方法必须要是用virtual虚方法
• EnableClassInterceptors + 特性标记在抽象上，所有实现类都支持AOP
• EnableClassInterceptors + 特性标记到实现类上，标记的类就支持AOP

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().As<IPhone>().EnableInterfaceInterceptors();
containerBuilder.RegisterType(typeof(CustomInterceptor));
IContainer container = containerBuilder.Build();
IPhone phone = container.Resolve<IPhone>();
phone.ShowName();

（5）运行结果

方法执行前。。。
Honer
方法执行后。。。

8、单抽象多实现问题

（1）在容器中注册关系创建对象

注册的时候不标记名字，后注册的会覆盖先注册的
注册的时候标记下名字，创建对象的时候用名称来区分

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<Honer>().Named<IPhone>("Honer");
containerBuilder.RegisterType<Huawei>().Named<IPhone>("Huawei");
IContainer container = containerBuilder.Build();
IPhone honer = container.ResolveNamed<IPhone>("Honer");
IPhone huawei = container.ResolveNamed<IPhone>("Huawei");
honer.ShowName();
huawei.ShowName();

（2）运行结果

Honer
Huawei

9、集成到Asp.NetCore5框架

（1）nuget引入程序集

Autofac
Autofac.Extensions.DependencyInjection

（2）定义实现类和抽象

public class UserService : IUserService
{    
    private IUserRepository UserRepositoryCtor { get; set; }
    public UserService(IUserRepository userRepository)
    {
        UserRepositoryCtor = userRepository;
    }    
    public string Login(string username, string password)
    {
        return "登录成功";
    }
}

（3）添加控制器和页面

public class FourthController : Controller
{
    private IUserService _userService;
    public FourthController(IUserService userService)
    {
        this._userService = userService;
    }
    public IActionResult Index()
    {
        object result = this._userService.Login("username", "password");
        return View(result);
    }
}

@model String
<h2>this is fourth index...</h2>
<h2>@Model</h2>

（4）在Program替换容器工厂

public class Program
{
    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            })
            .UseServiceProviderFactory(new AutofacServiceProviderFactory());
}

（5）在Startup类的ConfigureServices方法中替换创建控制器的类

//控制器默认是有IControllerActivator创建的，替换成由容器创建
services.Replace(ServiceDescriptor.Transient<IControllerActivator, ServiceBasedControllerActivator>());

（6）注册抽象和实现的关系

在Startup类中专门增加一个方法ConfigureContainer，用于注册抽象和实现，可以把这些注册信息进行模块化封装到AutofacModule

当抽象类和实现非常多的时候，可以将整个dll注册，特殊的关系可以写在后面覆盖前面的注册关系。

/// <summary>
/// Autofac专用：注册抽象和细节之间的关系，使用autofac后原来内置注册的关系要注释掉
/// Autofac和ServiceCollection是二者并存的，Autofac会接管ServiceCollection的一切
/// </summary>
/// <param name="builder"></param>
public void ConfigureContainer(ContainerBuilder builder)
{
    builder.RegisterModule<AutofacModule>();
}

public class AutofacModule : Module
{
    /// <summary>
    /// 重写Autofac管道中的Load方法，在这里注入注册的内容
    /// </summary>
    /// <param name="builder"></param>
    protected override void Load(ContainerBuilder builder)
    {
        //注册抽象与实现
        builder.RegisterType<UserRepository>().As<IUserRepository>();
        builder.RegisterType<UserService>().As<IUserService>();

        //注册所有控制器类
        var controllersTypesInAssembly = typeof(Startup).Assembly.GetExportedTypes()
         .Where(type => typeof(ControllerBase).IsAssignableFrom(type)).ToArray();
        //实现属性注入，这边无法实现方法注入
        builder.RegisterTypes(controllersTypesInAssembly).PropertiesAutowired();
    }
}

（7）运行结果

（8）在Startup的Configure方法中用容器创建对象

using (var container = host.Services.CreateScope())
{
    IUserService userService = container.ServiceProvider.GetService<IUserService>();
}

（9）单抽象多实现集成到框架

注入的时候通过构造函数或者属性注入autofac上下文实例，再根据名称创建对应实例。

定义单抽象和多实例类

//抽象
public interface ITestService
{
    string Show();
}
//实现1
public class TestServiceA : ITestService
{
    public string Show()
    {
        return "TestServiceA";
    }
}
//实现2
public class TestServiceB : ITestService
{
    public string Show()
    {
        return "TestServiceB";
    }
}

在AutofacModule注册抽象和实现的关系

//单抽象多实现注册
builder.RegisterType<TestServiceA>().Named<ITestService>("a");
builder.RegisterType<TestServiceB>().Named<ITestService>("b");

添加控制器和页面

public class FifthController : Controller
{
    private IComponentContext _componentContext;

    public FifthController(IComponentContext componentContext)
    {
        this._componentContext = componentContext;
    }

    public IActionResult Index()
    {
        ITestService testServiceA = _componentContext.ResolveNamed<ITestService>("a");
        ITestService testServiceB = _componentContext.ResolveNamed<ITestService>("b");
        object result = $"{testServiceA.Show()}--{testServiceB.Show()}";
        return View(result);
    }
}

@model String
<h2>this is Fifth index...</h2>
<h2>@Model</h2>

运行结果