c# - 这是表示抽象工厂模式的好例子吗

Question

想检查这是否是表示抽象工厂模式的好例子。这里是主题戴尔(工厂)制造 xps(产品)戴尔(工厂)制造 inspiron(产品)惠普(工厂)使使节(产品)hp(工厂)制造 presario(产品)

BestBuy 销售电脑。

//Abstract factory
abstract class ComputerFactory
{
    public abstract Computer BuildComputer(Computer.ComputerType compType);
}

//Concrete factory
class Dell : ComputerFactory
{
    public override Computer BuildComputer(Computer.ComputerType compType)
    {
        if (compType == Computer.ComputerType.xps)
            return (new xps());
        else if (compType == Computer.ComputerType.inspiron)
            return new inspiron();
        else
            return null;
    }
}

//Concrete factory
class Hp : ComputerFactory
{
    public override Computer BuildComputer(Computer.ComputerType compType)
    {
        if (compType == Computer.ComputerType.envoy)
            return (new envoy());
        else if (compType == Computer.ComputerType.presario)
            return new presario();
        else
            return null;
    }
}

//Abstract product
public abstract class Computer
{
    public abstract string Mhz { get; set; }
    public enum ComputerType
    {
        xps,
        inspiron,
        envoy,
        presario
    }
}

//Concrete product for DELL
public class xps : Computer
{
    string _mhz = string.Empty;

    public override string Mhz
    {
        get
        {
            return _mhz;
        }
        set
        {
            _mhz = value;
        }
    }
}

//Concrete product for DELL
public class inspiron : Computer
{
    string _mhz = string.Empty;

    public override string Mhz
    {
        get
        {
            return _mhz;
        }
        set
        {
            _mhz = value;
        }
    }
}

//Concrete product for HP
public class envoy : Computer
{
    string _mhz = string.Empty;

    public override string Mhz
    {
        get
        {
            return _mhz;
        }
        set
        {
            _mhz = value;
        }
    }
}

//Concrete product for HP
public class presario : Computer
{
    string _mhz = string.Empty;

    public override string Mhz
    {
        get
        {
            return _mhz;
        }
        set
        {
            _mhz = value;
        }
    }
}

public class BestBuy
{
    ComputerFactory compFactory;
    Computer comp;
    public BestBuy(Computer.ComputerType compType)
    {
        if (compType == Computer.ComputerType.xps || compType == Computer.ComputerType.inspiron)
            compFactory = new Dell();
        else
            compFactory = new Hp();

        comp = compFactory.BuildComputer(compType);
    }

    public Computer Sell()
    {
        return comp;
    }
}

提前致谢。

Answer 1

这是模式部分的一个很好的例子。对象的基本构造是一个不错的示例，但是，逻辑依赖于单个 Computer.ComputerType 枚举。这个枚举需要提前知道每家工厂暴露的每一种计算机类型。

通常，使用抽象工厂的动机是从图片中抽象出那种类型的硬编码需求。添加一个 ComputerType 类并允许工厂返回可用类型的集合可能比使用单个枚举更好。然后，您可以使用返回的 ComputerType 构建新系统。

这允许您在不更改 API 的情况下添加其他工厂，这是抽象工厂模式的主要优点之一。阅读 Abstract Factory Pattern - 要点之一是:

The client does not know (or care) which concrete objects it gets from each of these internal factories since it uses only the generic interfaces of their products.

在这种情况下，您将已知类型“硬编码”到枚举中，这违反了模式的这一部分。