如何通过继承使用Singleton模式? [英] How to use the Singleton pattern via inheritance?

问题描述

我试图通过我的抽象Charcter类使用Singleton设计模式，以便所有子类都可以访问对象实例.这是我的单例课程:

I am trying to use the Singleton design pattern via my abstract Charcter class so all sub classes can acces the object instance. Here is my singleton class:

 class GatewayAccess

{
private static GatewayAccess ph;

// Constructor is 'protected'
protected GatewayAccess()
{
}

public static GatewayAccess Instance()
{
  // Uses lazy initialization.
  // Note: this is not thread safe.
  if (ph == null)
  {
      ph = new GatewayAccess();
      Console.WriteLine("This is the instance");
  }

  return ph;
}
}

我可以在program.cs中使用它来创建实例，没问题:

I can use this in my program.cs to create an instance no problem:

static void Main(string[] args)
    {
        GameEngine multiplayer = new GameEngine(5);

        Character Thor = new Warrior();
        Thor.Name = "Raymond";
        Thor.Display();
        Thor.PerformFight();
        Thor.PerformFight();
        multiplayer.Attach(Thor);

        GatewayAccess s1 = GatewayAccess.Instance();
        GatewayAccess s2 = GatewayAccess.Instance();

        if (s1 == s2)
        {
            Console.WriteLine("They are the same");
        }

        Console.WriteLine(Thor.getGamestate());

        Console.ReadLine();
    }

所以我想做的是允许子类(即warrior)访问Gateway的实例，我只是不知道如何做到这一点，因为继承的东西使我感到困惑.基本上，网关访问是对数据库的访问点，该数据库只能一次只有一个连接.单例模式很容易理解，只是它与继承的结合.我希望一旦实现这一目标，便可以以线程安全的方式做到这一点.

So what I want to do is allow the subclasses ie, warrior to access the instance of the Gateway, I just cannot figure out how to do this as the inheritance stuff is confusing me. Basically the gateway access is an access point to a database that can only have one connection at once. The singleton pattern was easy enough to understand, its just the mix of that and the inheritance. I was hoping once I achieved this, I could then do it in a thread safe manner.

我还想知道如何删除Singleton实例，因为它是与数据库的连接，一次只能由一个字符对象使用，然后一旦完成字符对象，它就必须释放单例对象对不对?

I was also wondering how the Singleton instance could be dropped, as it is a connection to a database and can only be used by one character object at a time, then once the character object is done with it, it must free the singleton object up right?

我试图使用我的Character类中的方法来完成所有这些操作，但是它不起作用.

I tried to use methods in my Character class to do all this but it isn't working.

我对此表示感谢.

推荐答案

我在这里感觉到一些设计异味.

I sense several design smells here.

• 数据库连接不应该是Singleton-正如您自己提到的那样，连接来来去去，而Singleton的要点是它在应用程序的生命周期中一直存在
• 单线程和线程安全性不是很好的匹配
• 游戏角色不必使用网关(来吧，战士对数据库有什么用?;-)

您最好将关注点分开，并让DB/持久性由另一个类来处理，这些类调用游戏角色，而不是相反.

You should better separate concerns and have DB / persistence handled by a different class which calls the game characters rather than vice versa.

仅凭您提供的少量信息很难给出更具体的建议.

It is difficult to give more specific advice with the little information you provided.

这篇关于如何通过继承使用Singleton模式?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！