c# - 使子对象具有自己的类型静态容器

每个类对象是否都有自己的静态数据存储区？

我的意思是，仅执行以下操作：

class Program
{
    static void Main(string[] args)
    {
        var car1 = new Car();
        car1.Save(); ////saves in its own storage
        var own1 = new Owner();
        own1.Save(); //saves in its own storage as well
    }
}

在我尝试的代码中，出现了这样的错误


  'System.InvalidCastException`


在这个地方
var repo = (Repository<IEntity>) CurrentRepository;

怎么了，我该怎么做？

整个代码在这里：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            //var car1 = new Car();
            //car1.Save(); ////saves in its own storage
            //var own1 = new Owner();
            //own1.Save(); //saves in its own storage as well    var car1 = new Car();

        }
    }

    public interface IEntity
    {
        long Id { get; }
    }

    public class Owner : Entity
    {

        public string FirstName { get; set; }

        public string LastName { get; set; }

        public Car Car { get; set; }

        public Owner(string firstName, string lastName, Car car) : base(new Owner())
        {
            FirstName = firstName;
            LastName = lastName;
            Car = car;
        }

        public Owner() : base()
        {
        }

    }

    public class Car : Entity
    {
        public string Name { get; set; }
        public int Year { get; set; }

        public Car() : base()
        {

        }

        public Car(string name, int year)
        {
            Name = name;
            Year = year;
        }
    }

    public abstract class Entity : IEntity
    {
        public long Id { get; }

        public static object CurrentRepository { get; set; }

        public Entity(Entity ent)
        {
            Type entityType = ent.GetType();
            var instance = Activator.CreateInstance(typeof(Repository<>).MakeGenericType(entityType));

            CurrentRepository = instance;

        }

        public Entity()
        {
        }

        public void Save()
        {
            var repo = (Repository<IEntity>)CurrentRepository;
            repo.Save(this);
        }

        public void Delete()
        {
            var repo = (Repository<IEntity>)CurrentRepository;
            repo.Delete(this);
        }
    }

    public interface IRepository<T> where T : IEntity
    {
        void Save(T entity);
        void Delete(T entity);
        T Find(long id);
    }

    public class Repository<T> : IRepository<T> where T : class, IEntity
    {
        protected BaseStorage<T> CustomDataStorage;

        public Repository()
        {
            CustomDataStorage = new BaseStorage<T>();
        }

        public void Save(T entity)
        {
            CustomDataStorage.Add(entity);
        }

        public void Delete(T entity)
        {
            CustomDataStorage.Remove(entity);
        }

        public T Find(long id)
        {
            throw new NotImplementedException();
        }
    }
    public class BaseStorage<T> : IStorage<T>
    {
        List<T> data = new List<T>();

        public void Add(T entity)
        {
            data.Add(entity);
        }

        public void Remove(T entity)
        {
            throw new NotImplementedException();
        }
    }

    public interface IStorage<T>
    {
        void Add(T entity);
        void Remove(T entity);
    }

}

最佳答案

在我尝试的代码中，出现了这样的错误
  
  
    'System.InvalidCastException`
  
  
  在这个地方var repo =（Repository）CurrentRepository;
  
  怎么了，我该怎么做？


这是因为您不能直接将类型为（CurrentRepository或Repository<Car>）的Repository<Owner>强制转换为Repository<IEntity>。

有关更多信息，请参见here。



要在这里实现您想要的功能，可以尝试这种方式：


使Entity类为泛型（Entity<T>），并将泛型类型约束为IEntity
将CurrentRepository设置为Repository<Entity<T>>
将CurrentRepository的静态初始化从实例构造函数移动到静态构造函数。
使用Owner使Car的Entity<T>和T对象子类引用其自身的类型，使其成为自引用泛型


码：

public class Owner : Entity<Owner>
{
  ...
}

public class Car : Entity<Car>
{
  ...
}

public abstract class Entity<T> : IEntity
  where T: IEntity
{
  public long Id { get; }

  public static Repository<Entity<T>> CurrentRepository { get; set; }

  static Entity()
  {
    CurrentRepository = new Repository<Entity<T>>();
  }

  public Entity()
  {
  }

  public void Save()
  {
    CurrentRepository.Save(this);
  }

  public void Delete()
  {
    CurrentRepository.Delete(this);
  }
}