Unity(IoC)

一、什么是IoC?

     IoC(Inversion of Control,控制反转)又称“依赖注入”(Dependence Injection,DI)。

     控制反转就是创建对象的权利由开发人员控制，转为由容器来控制。

     依赖注入就是通过容器创建对象的，是通过在构造方法的参数，属性设置和接口等方式注入的。

     IoC的基本概念是：不创建对象，但是描述创建它们的方式。在代码中不直接与对象和服务连接，但在配置文件（或程序）中描述创建关系，容器负责将它们联系起来。

二、什么是Unity?

     Unity是微软开发的一款轻量级、可扩展的IoC框架，可通过代码或者XML配置文件的形式来配置对象和对象直接的关系。

     在运行时直接调用容器即可获得我们需要的对象，以便建立松耦合的程序。

三、创建Unity Demo

     1.新建控制台项目UnityDemo

     2.右键UnityDemo项目，选择“管理NuGet程序包”，安装Unity程序包

     3.新建几个接口IPhone，IHeadphone，IMicrophone，IPower

public interface IHeadphone
    {

    }
 public interface IMicrophone
    {

    }
  public interface IPower
    {

    }
 public interface IPhone
    {
        /// <summary>
        /// 打电话
        /// </summary>
        void Call();

        IMicrophone iMicrophone { get; set; }
        IHeadphone iHeadphone { get; set; }
        IPower iPower { get; set; }
    }

    4.新建继承接口的类

 public class Headphone:IHeadphone
    {

    }
public class Microphone: IMicrophone
    {
    }

public class Power:IPower
    {
    }

 public class AndroidPhone : IPhone
    {
        public IHeadphone iHeadphone { get; set; }

        public IMicrophone iMicrophone { get; set; }


        public IPower iPower { get; set; }

        public AndroidPhone()
        {
            Console.WriteLine("{0}构造函数", this.GetType().Name);
        }

        public void Call()
        {
            Console.WriteLine("{0}打电话", this.GetType().Name); 
        }
    }

public class ApplePhone : IPhone
    {
        [Dependency] //属性注入
        public IHeadphone iHeadphone { get; set; }

        public IMicrophone iMicrophone { get; set; }

        public IPower iPower { get; set; }

        public ApplePhone()
        {
            Console.WriteLine("{0}构造函数", this.GetType().Name);
        }

        [InjectionConstructor] //构造函数注入
        public ApplePhone(IMicrophone iMicrophone)
        {
            this.iMicrophone = iMicrophone;

            Console.WriteLine("{0}带参数构造函数", this.GetType().Name);
        }

        public void Call()
        {
            Console.WriteLine("{0}打电话", this.GetType().Name);
        }

        [InjectionMethod]  //属性注入
        public void Init(IPower iPower)
        {
            this.iPower = iPower;
        }
    }

 四、编程方式注册对应关系

      Unity有三种注入方式：1.属性注入，使用[Dependency]特性  2.构造方法注入，使用[InjectionConstructor]特性（没有此特性，默认使用参数最多的构造方法）  3.方法注入，使用[InjectionMethod]特性

      1.创建一个UnityContainer对象

      2.通过UnityContainer对象的RegisterType方法来注册对象和对象之间的关系

      3.通过UnityContainer对象的Resolve方法来获取指定对象关联的对象

static void Main(string[] args)
        {
            try
            {
                Console.WriteLine("********************AndroidPhone**********************");
                {
                    IUnityContainer container = new UnityContainer();
                    container.RegisterType<IPhone, AndroidPhone>();
                    container.RegisterType<IHeadphone, Headphone>();
                    container.RegisterType<IMicrophone, Microphone>();
                    container.RegisterType<IPower, Power>();
                    IPhone phone = container.Resolve<IPhone>();
                    phone.Call();
                    //未注入   iHeadphone，iMicrophone，iPower 对象都为空             
                    Console.WriteLine("phone.iHeadphone == null? {0}", phone.iHeadphone == null);
                    Console.WriteLine("phone.iMicrophone == null? {0}", phone.iMicrophone == null);
                    Console.WriteLine("phone.iPower == null? {0}", phone.iPower == null);
                }

                Console.WriteLine("********************ApplePhone**********************");
                {
                    IUnityContainer container = new UnityContainer();
                    container.RegisterType<IPhone, ApplePhone>();
                    container.RegisterType<IHeadphone, Headphone>();
                    container.RegisterType<IMicrophone, Microphone>();
                    container.RegisterType<IPower, Power>();
                    IPhone phone = container.Resolve<IPhone>();
                    phone.Call();
                    //通过属性注入，构造函数注入，方法注入   iHeadphone，iMicrophone，iPower 对象不为空    
                    Console.WriteLine("phone.iHeadphone == null? {0}", phone.iHeadphone == null);
                    Console.WriteLine("phone.iMicrophone == null? {0}", phone.iMicrophone == null);
                    Console.WriteLine("phone.iPower == null? {0}", phone.iPower == null);
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            Console.ReadKey();
        }

  运行结果：

五、通过配置文件配置对应关系

     项目结构：

    配置文件：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, Microsoft.Practices.Unity.Configuration" />
  </configSections>
  <unity>
    <!--定义别名-->
    <aliases>     
      <add alias="IPhone" type="UnityDemo.Interface.IPhone,UnityDemo" />
      <add alias="IHeadphone" type="UnityDemo.Interface.IHeadphone,UnityDemo" />
      <add alias="IMicrophone" type="UnityDemo.Interface.IMicrophone,UnityDemo" />
      <add alias="IPower" type="UnityDemo.Interface.IPower,UnityDemo" />

      <add alias="AndroidPhone" type="UnityDemo.Service.AndroidPhone,UnityDemo" />
      <add alias="ApplePhone" type="UnityDemo.Service.ApplePhone,UnityDemo" />
      <add alias="Headphone" type="UnityDemo.Service.Headphone,UnityDemo" />
      <add alias="Microphone" type="UnityDemo.Service.Microphone,UnityDemo" />
      <add alias="Power" type="UnityDemo.Service.Power,UnityDemo" />
    </aliases>
    <!--容器-->
    <container name="MyContainer">
      <!--映射关系-->
      <register type="IPhone" mapTo="ApplePhone"/>
      <register type="IHeadphone" mapTo="Headphone"/>
      <register type="IMicrophone" mapTo="Microphone"/>
      <register type="IPower" mapTo="Power"/>
    </container>
  </unity>
</configuration>

   调用代码：

public static void ContainerConfiguration()
        {
            IUnityContainer container = new UnityContainer();
            ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap { ExeConfigFilename ="Unity.config"};
            Configuration configuration =  ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None);
            UnityConfigurationSection section =(UnityConfigurationSection)configuration.GetSection("unity");
            container.LoadConfiguration(section, "MyContainer");
            IPhone phone = container.Resolve<IPhone>();
            phone.Call();
            //通过属性注入，构造函数注入，方法注入   iHeadphone，iMicrophone，iPower 对象不为空    
            Console.WriteLine("phone.iHeadphone == null? {0}", phone.iHeadphone == null);
            Console.WriteLine("phone.iMicrophone == null? {0}", phone.iMicrophone == null);
            Console.WriteLine("phone.iPower == null? {0}", phone.iPower == null);
        }