设计模式-工厂模式

简单工厂模式：

using System;

namespace CSharpDesignPattern.Factory
{
    public enum EnemyType
    {
        AirPlane = 0,
        Tank = 1,
    }

    public class SimpleFactory
    {
        private int screenWidth;
        private Random random;

        public SimpleFactory(int screenWidth)
        {
            this.screenWidth = screenWidth;
            this.random = new Random();
        }

        public Enemy Create(EnemyType type)
        {
            int x = random.Next(screenWidth);
            Enemy enemy = null;
            switch (type)
            {
                case EnemyType.AirPlane:
                    enemy = new AirPlane(x, 0);
                    break;
                case EnemyType.Tank:
                    enemy = new Tank(x, 0);
                    break;
            }
            return enemy;
        }
    }
}

通过接口实现各自的工厂模式

namespace CSharpDesignPattern.Factory
{
    public interface IFactory
    {
        Enemy Create(int screenWidth);
    }

    public class TankFactory : IFactory
    {
        public Enemy Create(int screenWidth)
        {
            Random rnd = new Random();
            return new Tank(rnd.Next(screenWidth), 0);
        }
    }
    public class AirplaneFactory : IFactory
    {
        public Enemy Create(int screenWidth)
        {
            Random rnd = new Random();
            return new AirPlane(rnd.Next(screenWidth), 0);
        }
    }
}