掌握Autofac：IOC容器实战指南

一、初识：

Autofa也是一款很流行的IOC容器：那如何使用？ 第三方的IOC容器；
1.Nuget引入程序包
● Autofac
● Autofac.Configuration
● Autofac.Extensions.DependencyInjection
2.创建一个ContainerBuilder
3.注册抽象和实现关系
4.Build一下，得到IContainer容器
5.通过容器获取服务实例
6.获取服务

二、Autoafa多种注入方式：

1.构造函数注入

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>();
containerBuilder.RegisterType<TestServiceB>().As<ITestServiceB>();
containerBuilder.RegisterType<TestServiceC>().As<ITestServiceC>(); 
IContainer container = containerBuilder.Build();
ITestServiceC testServiceC = container.Resolve<ITestServiceC>();//获取服务
testServiceC.Show();

2.属性注入

（1）全属性注入
关键字：PropertiesAutowired当前构造的实例中，所有的属性全部都要支持属性注入

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>();
containerBuilder.RegisterType<TestServiceB>().As<ITestServiceB>();
containerBuilder.RegisterType<TestServiceC>().As<ITestServiceC>();
containerBuilder.RegisterType<TestServiceD>().As<ITestServiceD>().PropertiesAutowired();
IContainer container = containerBuilder.Build();
ITestServiceD testServiceD = container.Resolve<ITestServiceD>();//获取服务
testServiceD.Show();

（2）选择属性注入

[AttributeUsage(AttributeTargets.Property)]
public class SelectPropAttribute : Attribute
{


}

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

对需要注入的类属性添加自定义的特性

public class TestServiceA
{
    [SelectProp]  //有值
    public IMicrophone MicrophoneProp0 { get; set; }
}

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>()
    .PropertiesAutowired(new CustomPropertySelector());
IContainer container = containerBuilder.Build();
ITestServiceD testServiceD = container.Resolve<ITestServiceD>();//获取服务
testServiceD.Show();

3.方法注入

ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<TestServiceA>()
    .OnActivated(
    	e => e.Instance.SetService(e.Context.Resolve<ITestServiceA>())
	)
    .As<ITestServiceB>(); 
IContainer container = containerBuilder.Build();
ITestServiceB testServiceA = container.Resolve<ITestServiceB>();//获取服务
testServiceB.Show();

public public class TestServiceA
{
    [SelectProp]  //有值
    public IMicrophone MicrophoneProp0 { get; set; }

    public void SetService(ITestServiceA testServiceA)
    {
    }
}

三、Autofac生命周期

1.瞬时生命周期–每次获取实例都是全新的实例

InstancePerDependency()
ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>().InstancePerDependency();
IContainer container = containerBuilder.Build();
ITestServiceA testServiceA = container.Resolve<ITestServiceA>();//获取服务
ITestServiceA testServiceA1 = container.Resolve<ITestServiceA>();//获取服务
Console.WriteLine(object.ReferenceEquals(testServiceA, testServiceA1));//false

2.单例生命周期 --一个进程中都是同一个实例

SingleInstance()
ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>().SingleInstance();
IContainer container = containerBuilder.Build();
ITestServiceA testServiceA = container.Resolve<ITestServiceA>();//获取服务
ITestServiceA testServiceA1 = container.Resolve<ITestServiceA>();//获取服务
Console.WriteLine(object.ReferenceEquals(testServiceA, testServiceA1));//true

3.每个生命周期范围一个实例

InstancePerLifetimeScope();
ContainerBuilder containerBuilder = new ContainerBuilder();
containerBuilder.RegisterType<TestServiceA>().As<ITestServiceA>().InstancePerLifetimeScope();
IContainer container = containerBuilder.Build();

ITestServiceA testServiceA15 = null;
ITestServiceA testServiceA16 = null; 
using (var scope1 = container.BeginLifetimeScope())
{
    ITestServiceA testServiceA11 = scope1.Resolve<ITestServiceA>();
    ITestServiceA testServiceA12 = scope1.Resolve<ITestServiceA>();
    Console.WriteLine(object.ReferenceEquals(testServiceA11, testServiceA12)); //true
    testServiceA15 = testServiceA12;
}

using (var scope1 = container.BeginLifetimeScope())
{
    ITestServiceA testServiceA13 = scope1.Resolve<ITestServiceA>();
    ITestServiceA testServiceA14 = scope1.Resolve<ITestServiceA>();
    Console.WriteLine(object.ReferenceEquals(testServiceA13, testServiceA14)); //true
    testServiceA16 = testServiceA14;
} 
Console.WriteLine(object.ReferenceEquals(testServiceA15, testServiceA16));//false

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