ASP.NET Core-一个服务多个不同实现依赖注入

实现类：

    public interface IPerson
    {
        string Get();
    }

    public class PersonA:IPerson
    { 
    public string Get() { return "PersonA"; }
    }

    public class PersonB : IPerson
    {
        public string Get() { return "PersonB"; }
    }

ConfigureService：

　　　　　　　services.AddSingleton<PersonA>();

            services.AddSingleton<PersonB>();

            services.AddSingleton(provider =>
            {
                Func<string, IPerson> accesor = (key) =>
                {
                    if (key == "a")
                    {
                        return provider.GetService<PersonA>();
                    }
                    else if (key == "b")
                    {
                        return provider.GetService<PersonB>();
                    }
                    else
                    {
                        throw new ArgumentException("key error");
                    }
                };
                return accesor;
            });

控制器：

public HomeController(Func<string,IPerson> func)
        {
            var personA = func("a");
            var personB = func("b");
            
            Console.WriteLine(personA.Get());
            Console.WriteLine(personB.Get());
            string a = "";
        }

...