反射实例--自己写个简单的IOC容器

一、先来看看项目的简单结构

二、新增类库：DemoIOC.IRepository

1.在类库下新建接口：IDemoRepository.cs

public interface IDemoRepository
{
  　　void Query();
}

三、新增类库：DemoIOC.Repository

1.在类库下新建类：DemoRepository.cs，继承接口：IDemoRepository.cs，并且实现接口的方法

public class DemoRepository : IDemoRepository
{
        public void Query()
        {
            Console.WriteLine("DemoRepository 的Query方法");
        }
}

四、新增类库：DemoIOC.IService

1.在类库下新建接口：IDemoService.cs

public interface IDemoService
{
        void Query();
}

五、新增类库：DemoIOC.Service

1.在类库下新建类：DemoService.cs ，继续接口：IDemoService.cs，并实现接口方法

2.新增构造函数，并且传入参数：IDemoRepository，用于实现函数注入

public class DemoService : IDemoService
{
        private readonly IDemoRepository _demoRepository;
        public DemoService(IDemoRepository demoRepository)
        {
            _demoRepository = demoRepository;
        }

        public void Query()
        {
            _demoRepository.Query();
        }
}

六、新增控制台程序：DemoIOC

1.新增类：ContainerIOC.cs  用于实现依赖注入

public class ContainerIOC
{
        private readonly Dictionary<string, Type> dic = new Dictionary<string, Type>();

        public  void Register<TFrom, TTo>() where TTo : TFrom
        {
            var fromName = typeof(TFrom).FullName;
            dic.Add(fromName, typeof(TTo));
        }

        public TFrom Resolve<TFrom>()
        {
            Type fromType = typeof(TFrom);
            return (TFrom)ResolveObject<TFrom>(fromType);
        }

        private object ResolveObject<TFrom>(Type type)
        {
            var key = type.FullName;
            Type toType = dic[key];
            var ctors = toType.GetConstructors();
            List<object> parameterList = new List<object>();
            foreach (var ctor in ctors)
            {
                var parameters = ctor.GetParameters();
                foreach (var parameter in parameters)
                {
                    var parameterType = parameter.ParameterType;
                    var parameterInstance = ResolveObject<TFrom>(parameterType);
                    parameterList.Add(parameterInstance);
                }
            }
            return Activator.CreateInstance(toType, parameterList.ToArray());
        }
}

七、测试结果

class Program
{
        static void Main(string[] args)
        {
            ContainerIOC container = new ContainerIOC();
            container.Register<IDemoRepository, DemoRepository>();
            container.Register<IDemoService, DemoService>();
            IDemoService repository = container.Resolve<IDemoService>();
            repository.Query();
        }
}