通过注解（特性）的方式进行对象的注册与注入，方便，灵活！

• 本篇主要讲如何去实现，下一篇主要讲如何把它集成到mvc和api环境里，实现自动的注入！

  spring ioc工作的过程大致为，统一的注册组件，拦截当前请求，统一的注入当前请求所需要的组件，事实上，说到这事，.net也完全可以实现这个功能和工作方式，下来大叔来实现一下

1. 定义组件注册特性
2. 定义组件生命周期
3. 定义组件注入特性
4. 定义Ioc工厂
5. 使用灵活方便
6. 将注入功能集成到mvc的拦截器里

定义组件注册特性

定义在类身上

    /// <summary>/// 注册组件特性./// </summary>[AttributeUsage(AttributeTargets.Class)]public class ComponentAttribute : Attribute{public LifeCycle LifeCycle { get; set; } = LifeCycle.CurrentScope;public String Named { get; set; }}

定义组件生命周期

    /// <summary>/// 组件生命周期/// </summary>public enum LifeCycle{CurrentScope,CurrentRequest,Global,}

定义组件注入特性

定义在字段上

    /// <summary>/// 注入一对象./// </summary>[AttributeUsage(AttributeTargets.Field)]public class InjectionAttribute : Attribute{public string Named{get;set;}}

定义Ioc工厂

    /// <summary>/// DI工厂./// </summary>public class DIFactory{static IContainer container;/// <summary>/// 手动注入./// </summary>/// <returns>The resolve.</returns>/// <typeparam name="T">The 1st type parameter.</typeparam>public static T Resolve<T>(){if (container == null)throw new ArgumentException("please run DIFactory.Init().");return container.Resolve<T>();}/// <summary>/// 手动注入./// </summary>/// <returns>The by named.</returns>/// <param name="named">Named.</param>/// <typeparam name="T">The 1st type parameter.</typeparam>public static T ResolveByNamed<T>(string named){if (container == null)throw new ArgumentException("please run DIFactory.Init().");return container.ResolveNamed<T>(named);}/// <summary>/// 把对象里的Inject特性的对象注入./// web环境下，应该使用filter拦截器将当前控制器传传InjectFromObject去注入它./// </summary>/// <param name="obj">Object.</param>public static void InjectFromObject(object obj){if (obj.GetType().IsClass && obj.GetType() != typeof(string))foreach (var field in obj.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Public)){if (field.GetCustomAttributes(false).Select(i => i.GetType()).Contains(typeof(InjectionAttribute))){InjectionAttribute inject = (InjectionAttribute)field.GetCustomAttributes(false).FirstOrDefault(i => i.GetType() == typeof(InjectionAttribute));if (inject != null && !String.IsNullOrWhiteSpace(inject.Named)){field.SetValue(obj, container.ResolveNamed(inject.Named, field.FieldType));}else{field.SetValue(obj, container.Resolve(field.FieldType));}//递归处理它的内部字段InjectFromObject(field.GetValue(obj));}}}/// <summary>/// 初始化./// </summary>public static void Init(){var builder = new ContainerBuilder();var arr = AppDomain.CurrentDomain.GetAssemblies().Where(x => !x.FullName.StartsWith("Dapper")&& !x.FullName.StartsWith("System")&& !x.FullName.StartsWith("AspNet")&& !x.FullName.StartsWith("Microsoft")).SelectMany(x => x.DefinedTypes).Where(i => i.IsPublic && i.IsClass).ToList();foreach (var type in arr){try{if (type.GetCustomAttributes(false).Select(i => i.GetType()).Contains(typeof(ComponentAttribute))){ComponentAttribute componentAttribute = (ComponentAttribute)type.GetCustomAttributes(false).FirstOrDefault(o => o.GetType() == typeof(ComponentAttribute));if (type.GetInterfaces() != null && type.GetInterfaces().Any()){type.GetInterfaces().ToList().ForEach(o =>{registor(builder, type, o, componentAttribute);});}else{registor(builder, type, type, componentAttribute);}}}catch (Exception){throw new Exception($"Lind.DI init {type.Name} error.");}}container = builder.Build();}/// <summary>/// 注册组件./// </summary>/// <param name="builder">Builder.</param>/// <param name="typeImpl">Type impl.</param>/// <param name="type">Type.</param>/// <param name="componentAttribute">Component attribute.</param>static void registor(ContainerBuilder builder, Type typeImpl, Type type, ComponentAttribute componentAttribute){if (componentAttribute.LifeCycle == LifeCycle.Global){if (componentAttribute.Named != null)builder.RegisterType(typeImpl).Named(componentAttribute.Named, type).SingleInstance();elsebuilder.RegisterType(typeImpl).As(type).SingleInstance();}else if (componentAttribute.LifeCycle == LifeCycle.CurrentScope){if (componentAttribute.Named != null)builder.RegisterType(typeImpl).Named(componentAttribute.Named, type).InstancePerLifetimeScope();elsebuilder.RegisterType(typeImpl).As(type).InstancePerLifetimeScope();}else{if (componentAttribute.Named != null)builder.RegisterType(typeImpl).Named(componentAttribute.Named, type).InstancePerRequest();elsebuilder.RegisterType(typeImpl).As(type).InstancePerRequest();}}}

使用灵活方便

支持对象与对象之间的依赖

   [Component(Named="RunPeople")]public class RunPeople : IRun{public void Do(){System.Console.WriteLine("人类跑起来!");}}[Component]public class Fly{[Injection(Named="RunPeople")]Run run;public void step1(){run.Do();System.Console.WriteLine("飞行第一步!");}}

使用方式，程序入口先初始化DIFactory.Init();

       [Injection]Fly flyObj;void print(){DIFactory.Init();DIFactory.InjectFromObject(this);flyObj.step1();}static void Main(string[] args){DIFactory.Init();System.Console.WriteLine("Hello World!");new Program().print();}

结果

Hello World!
人类跑起来!
飞行第一步!