有人可以批评我的工厂模式吗？

时间：2010-08-03 19:28:57

标签： design-patterns c#-4.0

我最近一直在学习更多关于设计模式的知识，并且我认为我会对它进行一些修改。我不确定这是否是使用工厂模式的正确方法，并且想知道是否有人可以向我提供反馈？

我基本上有一组相似的日历项目。膳食，锻炼和测量。它们都有日期和名称，可以打印详细信息。但除此之外，他们有一些项目，他们每个人都需要不同的东西。

    public enum AppointmentType
{
    Workout,
    Meal,
    Measurement
}

public abstract class Appointment
{
    public string Name { get; set; }
    public DateTime DateStarted { get; set; }

    public virtual string PrintDetails()
    {
        return string.Format("Type: {0}\nName: {1}\nDate: {2}",this.GetType().ToString(), Name, DateStarted.ToShortDateString());
    }
}

public class Workout : Appointment
{
    public List<string> Exercises { get; set; }

    public Workout()
    {
        Exercises = new List<string>();
    }

    public override string PrintDetails()
    {
        string startInfo = base.PrintDetails();
        string addedInfo = "\nToday I will be doing the following:\n";

        foreach (string exercise in Exercises)
        {
            addedInfo += string.Format("{0}\n", exercise);
        }

        return startInfo + addedInfo;
    }
}

public class Meal : Appointment
{
    public List<string> FoodItems { get; set; }

    public Meal()
    {
        FoodItems = new List<string>();
    }

    public override string PrintDetails()
    {
        string startInfo = base.PrintDetails();
        string addedInfo = "\nToday I will be eating the following:\n";

        foreach (string foodItem in FoodItems)
        {
            addedInfo += string.Format("{0}\n", foodItem);
        }

        return startInfo + addedInfo;
    }
}

public class Measurement : Appointment
{
    public string Height { get; set; }
    public string Weight { get; set; }

    public override string PrintDetails()
    {
        string startInfo = base.PrintDetails();
        string addedInfo = string.Format("\nI am {0} feet tall and I weight {1} pounds!\n", Height, Weight);
        return startInfo + addedInfo;
    }
}

public interface IAppointmentFactory
{
    Appointment CreateAppointment(AppointmentType appointmentType);
}

public class AppointmentFactory : IAppointmentFactory
{
    public Appointment CreateAppointment(AppointmentType appointmentType)
    {
        switch (appointmentType)
        {
            case AppointmentType.Workout:
                return new Workout();
            case AppointmentType.Meal:
                return new Meal();
            case AppointmentType.Measurement:
                return new Measurement();
            default:
                return new Workout();
        }
    }
}

这是一个使用该库的程序：

  class Program
{
    public static List<Appointment> myAppointments;
    public static AppointmentFactory factory;
    public static Appointment myAppointment;

    static void Main(string[] args)
    {
        myAppointments = new List<Appointment>();
        factory = new AppointmentFactory();
        StartLoop();
    }

    private static void StartLoop()
    {
        Console.WriteLine(string.Format("\nWelcome to Appointment App: You have {0} appointment(s)!", myAppointments.Count()));
        Console.WriteLine("0 = Exit");
        Console.WriteLine("1 = New Workout");
        Console.WriteLine("2 = New Meal");
        Console.WriteLine("3 = New Measurement");
        Console.WriteLine("P = Print Schedule\n");

        switch (Console.ReadLine().ToUpper())
        {
            case "0":
                return;
            case "1":
                CreateNewAppointment(AppointmentType.Workout);
                AddExercises();
                break;
            case "2":
                CreateNewAppointment(AppointmentType.Meal);
                AddFoodItems();
                break;
            case "3":
                CreateNewAppointment(AppointmentType.Measurement);
                GetMeasurements();
                break;
            case "P":
                PrintSchedule();
                break;
            default:
                return;
        }

        StartLoop();
    }

    private static void GetMeasurements()
    {
        Console.WriteLine("How tall are you?");
        ((Measurement)myAppointment).Height = Console.ReadLine();
        Console.WriteLine("What is your weight?");
        ((Measurement)myAppointment).Weight = Console.ReadLine();
    }

    private static void AddFoodItems()
    {
        Console.WriteLine("How many food items do you want to add?");
        string exerciseCount = Console.ReadLine();

        for (int i = 0; i < Convert.ToInt32(exerciseCount); i++)
        {
            Console.WriteLine(string.Format("Food {0}:", (i + 1)));
            ((Meal)myAppointment).FoodItems.Add(Console.ReadLine());
        }
    }

    private static void AddExercises()
    {
        Console.WriteLine("How many exercises do you want to add?");
        string exerciseCount = Console.ReadLine();

        for (int i = 0; i < Convert.ToInt32(exerciseCount); i++)
        {
            Console.WriteLine(string.Format("Exercise {0}:", (i + 1)));
            ((Workout)myAppointment).Exercises.Add(Console.ReadLine());
        }
    }

    private static void PrintSchedule()
    {
        foreach (Appointment appointment in myAppointments)
        {
            Console.WriteLine(appointment.PrintDetails());
        }
    }

    public static void CreateNewAppointment(AppointmentType appointmentType)
    {
        myAppointment = factory.CreateAppointment(appointmentType);

        Console.WriteLine("Name:");
        myAppointment.Name = Console.ReadLine();
        Console.WriteLine("Start Date:");
        myAppointment.Name = Console.ReadLine();

        myAppointments.Add(myAppointment);
    }
}

谢谢！

-ajax

3 个答案:

答案 0 :(得分：3)

以下是我将其更改为：

public enum AppointmentType
{
    Workout,
    Meal,
    Measurement
}

public abstract class Appointment
{
    public string Name { get; set; }
    public DateTime DateStarted { get; set; }

    public abstract void PrintDetails();
    public abstract void RequestInputFromUser();
}

public class Workout : Appointment
{
    private List<string> Exercises { get; set; }

    public Workout()
    {
        Exercises = new List<string>();
    }

    public override void PrintDetails()
    {
        string startInfo = base.PrintDetails();
        string addedInfo = "\nToday I will be doing the following:\n";

        foreach (string exercise in Exercises)
        {
            addedInfo += string.Format("{0}\n", exercise);
        }

        Console.WriteLine(StartInfo + addedInfo);
    }

    public override void RequestInputFromUser()
    {
        Console.WriteLine("How many exercises do you want to add?");
        string exerciseCount = Console.ReadLine();

        for (int i = 0; i < Convert.ToInt32(exerciseCount); i++)
        {
            Console.WriteLine(string.Format("Exercise {0}:", (i + 1)));
            Exercises.Add(Console.ReadLine());
        }
    }
}

public class Meal : Appointment
{
    private List<string> FoodItems { get; set; }

    public Meal()
    {
        FoodItems = new List<string>();
    }

    public override void PrintDetails()
    {
        string startInfo = base.PrintDetails();
        string addedInfo = "\nToday I will be eating the following:\n";

        foreach (string foodItem in FoodItems)
        {
            addedInfo += string.Format("{0}\n", foodItem);
        }

        Console.WriteLine(startInfo + addedInfo);
    }

    public override void RequestInputFromUser()
    {
        Console.WriteLine("How many food items do you want to add?");
        string exerciseCount = Console.ReadLine();

        for (int i = 0; i < Convert.ToInt32(exerciseCount); i++)
        {
            Console.WriteLine(string.Format("Food {0}:", (i + 1)));
            FoodItems.Add(Console.ReadLine());
        }
    }
}

public class Measurement : Appointment
{
    private string Height { get; set; }
    private string Weight { get; set; }

    public override void PrintDetails()
    {
        string startInfo = base.PrintDetails();
        string addedInfo = string.Format("\nI am {0} feet tall and I weight {1} pounds!\n", Height, Weight);
        Console.WriteLine(startInfo + addedInfo);
    }

    public override void RequestInputFromUser()
    {
        Console.WriteLine("How tall are you?");
        Height = Console.ReadLine();
        Console.WriteLine("What is your weight?");
        Weight = Console.ReadLine();
    }
}

public interface IAppointmentFactory
{
    Appointment CreateAppointment(AppointmentType appointmentType);
}

public class AppointmentFactory : IAppointmentFactory
{
    public Appointment CreateAppointment(AppointmentType appointmentType)
    {
        Appointment apt;

        switch (appointmentType)
        {
            case AppointmentType.Workout:
                apt = new Workout();
            case AppointmentType.Meal:
                apt = new Meal();
            case AppointmentType.Measurement:
                apt = new Measurement();
            default:
                apt = new Workout();
        }

        Console.WriteLine("Name:");
        apt.Name = Console.ReadLine();
        Console.WriteLine("Start Date:");
        apt.Name = Console.ReadLine();    // Logic error on this line.
                                          // Change it to do what you mean.

        apt.RequestInputFromUser();

        return apt;
    }
}

代码使用如下：

class Program
{
    public static List<Appointment> myAppointments;
    public static AppointmentFactory factory;
    public static Appointment myAppointment;

    static void Main(string[] args)
    {
        myAppointments = new List<Appointment>();
        factory = new AppointmentFactory();
        StartLoop(factory);
    }

    private static void StartLoop(IAppointmentFactory factory)
    {
        bool exit = false;

        while(!exit)
        {

            Console.WriteLine(string.Format("\nWelcome to Appointment App: You have {0} appointment(s)!", myAppointments.Count()));
            Console.WriteLine("0 = Exit");
            Console.WriteLine("1 = New Workout");
            Console.WriteLine("2 = New Meal");
            Console.WriteLine("3 = New Measurement");
            Console.WriteLine("P = Print Schedule\n");

            switch (Console.ReadLine().ToUpper())
            {
                case "0":
                    exit = true;
                    break;
                case "1":
                    myAppointments.Add( factory.CreateAppointment( AppointmentType.Workout ) );
                    break;
                case "2":
                    myAppointments.Add( factory.CreateAppointment( AppointmentType.Meal ) );
                    break;
                case "3":
                    myAppointments.Add( factory.CreateAppointment( AppointmentType.Measurement ) );
                    break;
                case "P":
                    PrintSchedule();
                    break;
                default:
                    exit = true;
            }

        }

    }

    private static void PrintSchedule()
    {
        foreach (Appointment appointment in myAppointments)
        {
            appointment.PrintDetails();
        }
    }

}

有几点需要注意：

  • 下层的所有属性都是私有的（好东西）
  • 没有类型铸造（另一件好事）
  • 很容易添加另一种约会类型（另一件好事）

仍有一些事情可以改变。具有公共属性的基类仍然是一件坏事。但这是一个很大的改进。

我还删除了对StartLoop（）的递归调用。当你需要的只是一个循环时，你不想增长堆栈。

编辑：对Factory类进行了一些更改。

回应评论：

  • 要删除对控制台的依赖关系，请创建一个代表您要对IO执行的操作的界面。创建实现此接口的类，并将实例发送到Appointment类。从那里开始，让一切都使用IO引擎的实例。要更改平台，请更改发送到Appointment类的IO实现类
  • 公共属性不好，因为公共变量不好。类应隐藏其实现，公共属性公开实现。有关详细信息，我建议Clean Code。它描述它比我做得好得多。
总的来说，还不错：）

答案 1 :(得分：0)

据我了解，当您需要创建相同类型对象的不同集合时，将使用抽象工厂模式。因此，例如，您可能有一个出售

的工厂 
Supersize-Workout
Supersize-Meal
Supersize-Measurement

和另一个出售

的人 
Mini-Workout
Mini-Meal
Mini-Measurement

然后可以将这些工厂类别提供给需要创建锻炼，膳食和测量的系统，但不管他们是否超大或迷你，只要他们都是相同的。

在没有第二家工厂的情况下，我觉得你的抽象工厂有点奇怪。

答案 2 :(得分：0)

嗯，对于初学者 - 你的代码很好地遵循了模式。

您的特定实现会遇到一些问题（但无法解决的问题）：

  1. 对参数使用枚举违反了OCP原则。如果您添加或更糟糕，从枚举中删除值，客户端将不得不重新编译以使用正确的（新）枚举。对于教科书答案 - 您可以使用字符串来表示您要创建的类型，然后在请求不受支持的类型时以其他方式抛出异常/处理它。

  2. 添加新的Factory实现将被强制仅支持原始工厂可以处理的相同返回类型 - 除非您可以重新编译（再次违反OCP）。根据您的情况 - 这可能没问题。

    3. 但除此之外 - 在我看来，这是一个可行的实施方案。

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