[Solution] DI原理解析及Castle、Unity框架使用

本节目录

DI介绍

控制反转（Inversion of Control，英文缩写为IoC）是一个重要的面向对象编程的法则来削减计算机程序的耦合问题.

依赖注入（Dependency Injection,英文缩写为DI）是一种设计模式.

其实本质都是指同一件事,强调的内容不一样.IoC强调容器的作用,DI强调注入的作用.

通常IoC和DI可以理解为一个意思,只是指的对象不同.

 

DI基本原理

DI本质上是通过容器来反射创建实例.

 

1个简单的类

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class Person
{
    public void Say()
    {
        Console.WriteLine("Person's say method is Called");
    }
}

 

 反射代码(className:类的全限定名)

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private static object CreateInstance(Assembly assembly, string className)
{
    var type = assembly.GetType(className);
    return type != null ? Activator.CreateInstance(type) : null;
}

 

执行(XX为命名空间)

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static void Main(string[] args)
{
    var obj = CreateInstance(Assembly.GetExecutingAssembly(), "XX.Person");
    var person = obj as Person;
    if (person != null)
    {
        person.Say();
    }
    Console.ReadKey();
}

在上面能看到1个问题,一般情况下.既然使用DI,就不知道具体的注入对象.所以强调面向接口编程.

所以实际上一般先定义接口,再通过DI容器创建对象.

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interface IPerson
{
    void Say();
}
class Person : IPerson
{
    public void Say()
    {
        Console.WriteLine("Person's say method is Called");
    }
}

执行

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static void Main(string[] args)
{
    var obj = CreateInstance(Assembly.GetExecutingAssembly(), "Demo.Person");
    var person = obj as IPerson;
    if (person != null)
    {
        person.Say();
    }
    Console.ReadKey();
}

 

DI框架

DI框架流行的有Castle Windsor,Unity...(Autofac Spring.Net已经聊过,不再演示)

在DI框架中,一般需要将对象注册到容器中,然后从容器解析出来.

 

Castle

Install-Package Castle.Windsor

待注入类

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interface ITransient
  {
        
  }
 
  interface IPerson
  {
      void Say();
  }
  class Person : IPerson, ITransient
  {
      public void Say()
      {
          Console.WriteLine("Person's say method is Called");
      }
  }

 

注册解析方式一

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static void Main(string[] args)
{
    using (var container = new WindsorContainer())
    {
        container.Register(Component.For<Person, IPerson>());
        var person = container.Resolve<IPerson>();
        person.Say();
    }
    Console.ReadKey();
}

注册解析方式二

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public class AssmInstaller : IWindsorInstaller
{
    public void Install(IWindsorContainer container, IConfigurationStore store)
    {
        container.Register(Classes.FromThisAssembly()   //选择Assembly
            .IncludeNonPublicTypes()                    //约束Type
            .BasedOn<ITransient>()                         //约束Type
            .WithService.DefaultInterfaces()            //匹配类型
            .LifestyleTransient());                     //注册生命周期
    }
}
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static void Main(string[] args)
{
    using (var container = new WindsorContainer())
    {
        container.Install(new AssmInstaller());
        var person = container.Resolve<IPerson>();
        person.Say();
    }
    Console.ReadKey();
}

构造函数注入

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class Task : ITransient
{
    public IPerson Person { get; set; }
    public Task(IPerson person)
    {
        Person = person;
        Person.Say();
    }
}
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static void Main(string[] args)
{
    using (var container = new WindsorContainer())
    {
        container.Install(new AssmInstaller());
        container.Resolve<Task>();
    }
    Console.ReadKey();
}

属性注入

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class Task : ITransient
{
    public IPerson Person { get; set; }
    public Task()
    {
    }
    public void Say()
    {
        Person.Say();
    }
}
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static void Main(string[] args)
{
    using (var container = new WindsorContainer())
    {
        container.Install(new AssmInstaller());
        container.Resolve<Task>().Say();
    }
    Console.ReadKey();
}

MVC集成

Install-Package Castle.Windsor.Mvc

 

Application_Start注册

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protected void Application_Start()
{
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    var container = new WindsorContainer()
        .Install(FromAssembly.This());
    var controllerFactory = new WindsorControllerFactory(container.Kernel);
    ControllerBuilder.Current.SetControllerFactory(controllerFactory);
}

 

 

Installer注册

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public class AssmInstaller : IWindsorInstaller
{
    public void Install(IWindsorContainer container, IConfigurationStore store)
    {
        container.Register(Classes.FromThisAssembly()
            .IncludeNonPublicTypes()
            .BasedOn<ITransient>()
            .WithService.DefaultInterfaces()
            .LifestyleTransient());
        container.Register(Classes.FromThisAssembly()
            .BasedOn<Controller>()
            .LifestyleTransient()
            );
    }
}

这样Castle Windsor就能接管解析Controller了.

 

Unity

Install-Package Unity

待注入类

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public interface IPerson
{
    void Say();
}
public class Person : IPerson
{
    public void Say()
    {
        Console.WriteLine("Person's say method is Called");
    }
}

注册解析一

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static void Main(string[] args)
{
    using (var container = new UnityContainer())
    {
        container.RegisterType<IPerson, Person>(new TransientLifetimeManager());
        var person = container.Resolve<IPerson>();
        person.Say();
    }
    Console.ReadKey();
}

注册解析二

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static void Main(string[] args)
{
    using (var container = new UnityContainer())
    {
        container.RegisterInstance<IPerson>(new Person());
        var person = container.Resolve<IPerson>();
        person.Say();
    }
    Console.ReadKey();
}

构造函数注入

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class Task : ITask
{
    public IPerson Person { get; set; }
    public Task(IPerson person)
    {
        Person = person;
        Person.Say();
    }
}
 
public interface ITask
{
 
}
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static void Main(string[] args)
{
    using (var container = new UnityContainer())
    {
        container.RegisterInstance<IPerson>(new Person());
        container.RegisterType<ITask, Task>();
        container.Resolve<ITask>();
    }
    Console.ReadKey();
}

属性注入

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class Task : ITask
{
    [Dependency]
    public IPerson Person { get; set; }
    public Task(IPerson person)
    {
        Person = person;
    }
    public void Say()
    {
        Person.Say();
    }
}
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static void Main(string[] args)
{
    using (var container = new UnityContainer())
    {
        container.RegisterInstance<IPerson>(new Person());
        container.RegisterType<ITask, Task>();
        var task = container.Resolve<ITask>();
        task.Say();
    }
    Console.ReadKey();
}

MVC集成

Install-Package Unity.Mvc

 

Application_Start注册

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protected void Application_Start()
{
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    var container = new UnityContainer();
    container.RegisterType<IPerson, Person>();
    DependencyResolver.SetResolver(new UnityDependencyResolver(container));
}

这样Unity就接管了Controller的创建

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