asp.net core 依赖注入

 

    class Program
    {

        static void Main(string[] args)
        {
            new HomeController(new ServiceB()).print();
            Console.ReadLine();
        }
    }

    class HomeController
    {
        private IService _service;
        public HomeController(IService service)
        {
            _service = service;
        }
        public void print()
        {
            _service.output();
        }
    }

    interface IService
    {
        public void output();
    }

    class ServiceA : IService
    {
        public void output()
        {
            Console.WriteLine("AAA");
        }
    }
    class ServiceB : IService
    {
        public void output()
        {
            Console.WriteLine("BBB");
        }
    }

 

 

创建一个依赖注入容器

class Program
    {
        static void Main(string[] args)
        {

            //创建一个依赖注入容器（IServiceProvider）
            var service = new ServiceCollection().AddSingleton<IPerson, Teacher>().BuildServiceProvider().CreateScope().ServiceProvider;
            service.GetService<IPerson>();//Teacher构造
            var a = service.GetService<IPerson>();//因为是单例模式所以不会再创建新实例
            Console.WriteLine(a.GetType());//Teacher
        }
    }


    interface IPerson { }
    public class Student: IPerson
    {
        public Student() => Console.WriteLine("Student构造");
        public string name="TOM";
        public int age;
    }

    public class Teacher : IPerson
    {
        public Teacher() => Console.WriteLine("Teacher构造");
        public string name;
        public int age;
    }