通过 人打电话 来谈谈自己对IOC的理解
版本1.0
public class Person
{
public AndroidPhone Phone { get; set; }
public void CallForSomebody()
{
Phone.Call();
}
}
public class AndroidPhone
{
public void Call()
{
Console.WriteLine($"{this.GetType().Name} is calling");
}
}
class Program
{
static void Main(string[] args)
{
Person person = new Person
{
Phone = new AndroidPhone()
};
person.CallForSomebody();
Console.ReadKey();
}
}
如果这时候,想给这个人一部苹果手机,那么必须要修改 Person 类, 将属性Phone的类型改成:ApplePhone.这显然违背了OOP思想的"对修改封闭,对扩展开放"原则.同时该代码也不符合"接口分离原则",于是乎做如下调整.
版本2.0
public class Person
{
//定义 Phone 为 接口 IPhone 类型
public IPhone Phone { get; set; }
public void CallForSomebody()
{
Phone.Call();
}
}
public interface IPhone
{
void Call();
}
public class ApplePhone : IPhone
{
public void Call()
{
Console.WriteLine($"{this.GetType().Name} is calling");
}
}
public class AndroidPhone : IPhone
{
public void Call()
{
Console.WriteLine($"{this.GetType().Name} is calling");
}
}
控制台程序:
Person person = new Person();
//给这个人一部安卓手机
person.Phone = new AndroidPhone();
person.CallForSomebody();
//给这个人一部苹果手机
person.Phone = new ApplePhone();
person.CallForSomebody();
如果需要给诺基亚手机,只需要在创建一个诺基亚Phone类,实现 IPhone 接口,而不需要修改底层代码.
依赖注入有三种方式:
public class Person
{
//属性注入
public IPhone Phone { get; set; }
//构造函数注入
public Person(IPhone phone)
{
this.Phone = phone;
}
//方法注入
public void MethodInject(IPhone phone)
{
this.Phone = phone;
}
public void CallForSomebody()
{
Phone.Call();
}
}
版本2.0虽然不需要修改底层代码,但是控制台的代码依然需要修改,我们需要将 new AndridPhone() 更改成 new ApplePhone()
版本3.0 ( 利用 Unity )
学习新东西都是从 hello world 开始,先来一段 Unity 的 hello world
//创建一个IOC容器
IUnityContainer container = new UnityContainer();
//想要安卓手机就注册安卓手机
//container.RegisterType<IPhone, AndroidPhone>();
//想要苹果手机就注册苹果手机
container.RegisterType<IPhone, ApplePhone>();
IPhone phone = container.Resolve<IPhone>();
Person person = new Person(phone);
person.CallForSomebody();
这段代码其实 跟 版本2.0没什么区别,甚至还复杂了,版本2.0是改 new AndroidPhone() , 这里是改 container.RegisterType<IPhone, AndroidPhone>()
版本4.0
新建一个配置文件:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,Microsoft.Practices.Unity.Configuration"/>
</configSections>
<unity xmlns="http://schemas.microsoft.com/practices/2010/unity">
<containers>
<container name="unityContainer">
<!--type,mapTo:逗号左边是类的完全限定名,即命名空间+类名;逗号右边是程序集名称-->
<register type="IOCUnity.IPhone,IOCUnity" mapTo="IOCUnity.AndroidPhone,IOCUnity"></register>
</container>
</containers>
</unity>
</configuration>
控制台代码如下:
ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap
{
ExeConfigFilename = Path.Combine(AppDomain.CurrentDomain.BaseDirectory + @"UnityXml\UnityConfig.xml")
};
Configuration configuration = ConfigurationManager.OpenMappedExeConfiguration(fileMap,ConfigurationUserLevel.None);
UnityConfigurationSection section = (UnityConfigurationSection)configuration.GetSection(UnityConfigurationSection.SectionName);
IUnityContainer container = new UnityContainer();
section.Configure(container, "unityContainer");
IPhone phone = container.Resolve<IPhone>();
Person person = new Person(phone);
person.CallForSomebody();
如果要换成 ApplePhone , 只需要将 配置文件中 mapTo="IOCUnity.AndroidPhone,IOCUnity" 更改成 mapTo="IOCUnity.ApplePhone,IOCUnity"> 即可,源代码不需要做任何修改
版本4.5
配置文件修改: 添加 name 标记
<register type="IOCUnity.IPhone,IOCUnity" mapTo="IOCUnity.ApplePhone,IOCUnity" name="Apple"></register>
<register type="IOCUnity.IPhone,IOCUnity" mapTo="IOCUnity.AndroidPhone,IOCUnity" name="Android"></register>
//创建一个安卓手机
//IPhone phone = container.Resolve<IPhone>("Android");
//创建一个苹果手机
IPhone phone = container.Resolve<IPhone>("Android");
版本5.0
控制台代码:
ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap
{
ExeConfigFilename = Path.Combine(AppDomain.CurrentDomain.BaseDirectory + @"UnityXml\UnityConfig.xml")
};
Configuration configuration = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None);
UnityConfigurationSection section = (UnityConfigurationSection)configuration.GetSection(UnityConfigurationSection.SectionName);
IUnityContainer container = new UnityContainer();
section.Configure(container, "unityContainer");
Person person = container.Resolve<Person>();
/*
上面创建了一个person,虽然我们没有给它的属性Phone赋值,但实际上 Unity 已经帮我们注入了.
Unity 有三种特性 分别对应三种注入方式:
[InjectionConstructor] 构造函数注入
[dependency] 属性注入
[InjectionMethod] 方法注入
如果一个特性都不打,那么Unity 默认会采用 构造函数注入,并且是选用入参最多的那个构造函数注入.因此,推荐采用 构造函数注入,因为它是无侵入式的,不需要打任何特性.
*/
person.CallForSomebody();
public class Person
{
//属性注入
[Dependency]
public IPhone Phone { get; set; }
//构造函数注入
[InjectionConstructor]
public Person(IPhone phone)
{
this.Phone = phone;
}
//方法注入
[InjectionMethod]
public void MethodInject(IPhone phone)
{
this.Phone = phone;
}
public void CallForSomebody()
{
Phone.Call();
}
}
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section name="unity" type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,Microsoft.Practices.Unity.Configuration"/>
</configSections>
<unity xmlns="http://schemas.microsoft.com/practices/2010/unity">
<containers>
<container name="unityContainer">
<!--type,mapTo:逗号左边是类的完全限定名,即命名空间+类名;逗号右边是程序集名称-->
<register type="IOCUnity.IPhone,IOCUnity" mapTo="IOCUnity.ApplePhone,IOCUnity"></register>
<register type="IOCUnity.Person,IOCUnity" mapTo="IOCUnity.Person,IOCUnity"></register>
</container>
</containers>
</unity>
</configuration>