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问自动售货机
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Code Review用户

提问于 2017-03-25 11:29:12

回答 1查看 10.7K关注 0票数 7

在进行了大量的阅读和实践之后，我提出了一个简单的程序来实现多种OOP技术、原则和几种设计模式，比如观察者、工厂和单点对象。

该程序代表一个自动售货机与所有相关的行动和属性。自动售货机可以装满物品，客户可以购买特定的物品，机器屏幕通知客户其行动的结果等等。

VendingMachine.cs

public sealed class VendingMachine : ObserverCommands
{
    private static VendingMachine instance;

    private readonly Dictionary<Item, int> machineItems;
    private readonly Stack<SaleRecord> saleRecords;
    private double machineBank;
    private List<Observer> machineObservers;

    private VendingMachine()
    {
        this.machineItems = new Dictionary<Item, int>();
        this.saleRecords = new Stack<SaleRecord>();
        this.machineBank = 0;
        this.machineObservers = new List<Observer>();
    }

    public static VendingMachine GetInstance()
    {
        if (instance == null)
            instance = new VendingMachine();
        return instance;
    }
    public double MachineBank
    {
        get
        {
            return this.machineBank;
        }
    }
    public Dictionary<Item, int> MachineItems
    {
        get
        {
            return this.machineItems;
        }
    }
    public Stack<SaleRecord> SaleRecords
    {
        get
        {
            return this.saleRecords;
        }
    }

    public List<SaleRecord> GetLastSaleRecords(int num)
    {
        List<SaleRecord> list;

        if(num <= 0)
            return null;

        list = new List<SaleRecord>();

        foreach (SaleRecord saleRecord in saleRecords)
        {
            list.Add(saleRecord);
            if (--num == 0)
                break;
        }

        return list;
    }
    public int GetItemStock(Item item)
    {
        if (machineItems.ContainsKey(item))
            return machineItems[item];

        return -1;
    }
    public int GetTotalMachineItems()
    {
        int totalItems = 0;
        foreach (Item item in machineItems.Keys)
            totalItems += machineItems[item];
        return totalItems;

    }

    public void RefillItems()
    {
        machineItems.Clear();
        this.machineItems.Add(ItemFactory.GetItem("Coca Cola 330"), 20);
        this.machineItems.Add(ItemFactory.GetItem("Coca Cola Zero 330"), 20);
        this.machineItems.Add(ItemFactory.GetItem("Fuze Tea 500"), 20);
        this.machineItems.Add(ItemFactory.GetItem("Pepsi Max 330"), 20);
        this.machineItems.Add(ItemFactory.GetItem("Pepsi Max 500"), 10);
        this.machineItems.Add(ItemFactory.GetItem("Evian 500"), 10);
        this.machineItems.Add(ItemFactory.GetItem("Lays Barbecue"), 3);
        this.machineItems.Add(ItemFactory.GetItem("Lays Sour Cream & Onion"), 1);

        NotifyAllObservers(new VendingMachineLog("Machine has been refilled."));
    }
    public void SellItem(Item item, double amountPaid)
    {
        machineBank += item.ItemPrice;
        machineItems[item]--;
        NotifyAllObservers(new VendingMachineLog("Item has been sold."));
    }
    public void AddSaleRecord(SaleRecord saleRecord)
    {
        this.saleRecords.Push(saleRecord);
        NotifyAllObservers(new VendingMachineLog("Sale Record Added"));
    }

    public void RegisterObserver(Observer observer)
    {
        this.machineObservers.Add(observer);
    }
    public void UnregisterObserver(Observer observer)
    {
        this.machineObservers.Remove(observer);
    }
    public void NotifyAllObservers(VendingMachineLog log)
    {
        foreach (Observer observer in this.machineObservers)
            observer.Update(log);
    }

    public override string ToString()
    {
        return string.Format("Unique Items: {0}, Total Items: {1}, Total Sales: {2}, Machine Bank: {3}",
            machineItems.Count, GetTotalMachineItems(), saleRecords.Count, machineBank.ToString("C"));
    }
}

Item.cs，ItemFood.cs，ItemDrink.cs，ItemMakerType.cs

public abstract class Item : ICloneable
{
    private static int totalItemCount = 0;

    protected readonly int itemID;
    protected readonly string itemName;
    protected readonly ItemMakerType.Value itemMaker;
    protected readonly double itemPrice;

    public Item(string itemName, ItemMakerType.Value itemMaker, double itemPrice)
    {
        this.itemID = totalItemCount++;
        this.itemName = itemName;
        this.itemMaker = itemMaker;
        this.itemPrice = itemPrice;
    }
    public Item(Item item)
    {
        this.itemID = item.itemID;
        this.itemName = item.itemName;
        this.itemMaker = item.itemMaker;
        this.itemPrice = item.itemPrice;
    }

    public int ItemID
    {
        get
        {
            return this.itemID;
        }
    }
    public string ItemName
    {
        get
        {
            return this.itemName;
        }
    }
    public ItemMakerType.Value ItemMaker
    {
        get
        {
            return this.itemMaker;
        }
    }
    public double ItemPrice
    {
        get
        {
            return this.itemPrice;
        }
    }

    public static int TotalItems()
    {
        return totalItemCount;
    }

    public override string ToString()
    {
        return string.Format("[Item Details] ID: {0}, Name: {1}, Maker: {2}, Price: {3}",
            this.itemID, this.itemName, this.itemMaker.ToString(), itemPrice.ToString("C"));
    }
    public override bool Equals(object obj)
    {
        Item castedItem;
        try
        {
            castedItem = (Item)obj;
            return this.itemID == castedItem.itemID;
        }
        catch { }
        return false;
    }
    public override int GetHashCode()
    {
        return this.itemID;
    }

    public abstract Object Clone();
}
public class ItemFood : Item, IEatable
{
    protected int packCapacity;

    public ItemFood(string itemName, ItemMakerType.Value itemMaker, int packCapacity, double itemPrice)
        : base(itemName, itemMaker, itemPrice)
    {
        this.packCapacity = packCapacity;
    }
    public ItemFood(ItemFood itemFood) :
        base(itemFood)
    {
        this.packCapacity = itemFood.packCapacity;
    }

    public int PackCapacity
    {
        get
        {
            return this.packCapacity;
        }
    }

    public void Eat()
    {
        this.packCapacity = 0;
    }

    public override Object Clone()
    {
        return new ItemFood(this);
    }
    public override string ToString()
    {
        return string.Format("[FOOD] ID: {0}, Name: {1}, Maker: {2}, Price: {3}",
            this.itemID, string.Format("{0} ({1}g)", this.itemName, this.packCapacity), this.itemMaker, this.itemPrice.ToString("C"));
    }
}
public class ItemDrink : Item, IDrinkable
{
    protected int canCapacity;

    public ItemDrink(string itemName, ItemMakerType.Value itemMaker, int canCapacity, double itemPrice)
        : base(itemName, itemMaker, itemPrice)
    {
        this.canCapacity = canCapacity;
    }
    public ItemDrink(ItemDrink itemDrink) :
        base(itemDrink)
    {
        this.canCapacity = itemDrink.canCapacity;
    }

    public int CanCapacity
    {
        get
        {
            return this.canCapacity;
        }
    }
    public void Drink()
    {
        this.canCapacity = 0;
    }

    public override Object Clone()
    {
        return new ItemDrink(this);
    }
    public override string ToString()
    {
        return string.Format("[DRINK] ID: {0}, Name: {1}, Maker: {2}, Price: {3}",
            this.itemID, string.Format("{0} ({1}ml)", this.itemName, this.canCapacity), this.itemMaker, this.itemPrice.ToString("C"));
    }
}
public static class ItemMakerType
{
    public enum Value
    {
        CocaCola, PepsiCo, Faygo, Toscana, Regions, Fritolay
    }
}

ItemFactory.cs

public sealed class ItemFactory
{
    private static Dictionary<string, Item> cachedItems = new Dictionary<string, Item>();

    private static void LoadCachedItems()
    {
        cachedItems.Add("Coca Cola 330", new ItemDrink("Coca Cola Can", ItemMakerType.Value.CocaCola, 330, 1.49));
        cachedItems.Add("Coca Cola 500", new ItemDrink("Coca Cola Bottle", ItemMakerType.Value.CocaCola, 500, 2.49));
        cachedItems.Add("Coca Cola Diet 330", new ItemDrink("Coca Cola Diet Can", ItemMakerType.Value.CocaCola, 330, 1.49));
        cachedItems.Add("Coca Cola Diet 500", new ItemDrink("Coca Cola Diet Bottle", ItemMakerType.Value.CocaCola, 500, 2.49));
        cachedItems.Add("Coca Cola Zero 330", new ItemDrink("Coca Cola Zero Can", ItemMakerType.Value.CocaCola, 330, 1.49));
        cachedItems.Add("Coca Cola Zero 500", new ItemDrink("Coca Cola Zero Bottle", ItemMakerType.Value.CocaCola, 500, 2.49));
        cachedItems.Add("Sprite 330", new ItemDrink("Sprite Can", ItemMakerType.Value.CocaCola, 330, 1.49));
        cachedItems.Add("Sprite 500", new ItemDrink("Sprite Bottle", ItemMakerType.Value.CocaCola, 500, 2.49));
        cachedItems.Add("Sprite Diet 330", new ItemDrink("Sprite Diet Can", ItemMakerType.Value.CocaCola, 330, 1.49));
        cachedItems.Add("Sprite Diet 500", new ItemDrink("Sprite Diet Bottle", ItemMakerType.Value.CocaCola, 500, 2.49));
        cachedItems.Add("Fanta 330", new ItemDrink("Fanta Can", ItemMakerType.Value.CocaCola, 330, 1.49));
        cachedItems.Add("Fanta 500", new ItemDrink("Fanta Bottle", ItemMakerType.Value.CocaCola, 500, 2.49));
        cachedItems.Add("Fuze Tea 330", new ItemDrink("Fuze Tea Can", ItemMakerType.Value.CocaCola, 330, 1.49));
        cachedItems.Add("Fuze Tea 500", new ItemDrink("Fuze Tea Bottle", ItemMakerType.Value.CocaCola, 500, 2.49));
        cachedItems.Add("Pepsi 330", new ItemDrink("Pepsi Can", ItemMakerType.Value.PepsiCo, 330, 1.29));
        cachedItems.Add("Pepsi 500", new ItemDrink("Pepsi Bottle", ItemMakerType.Value.PepsiCo, 500, 2.29));
        cachedItems.Add("Pepsi Max 330", new ItemDrink("Pepsi Max Can", ItemMakerType.Value.PepsiCo, 330, 1.29));
        cachedItems.Add("Pepsi Max 500", new ItemDrink("Pepsi Max Bottle", ItemMakerType.Value.PepsiCo, 500, 2.29));
        cachedItems.Add("Evian 500", new ItemDrink("Evian Bottle", ItemMakerType.Value.Regions, 500, 1.79));
        cachedItems.Add("Aqua Panna 500", new ItemDrink("Aqua Panna Bottle", ItemMakerType.Value.Toscana, 500, 1.69));

        cachedItems.Add("Lays Classic", new ItemFood("Lays Classic", ItemMakerType.Value.Fritolay, 300, 2.99));
        cachedItems.Add("Lays Barbecue", new ItemFood("Lays Barbecue", ItemMakerType.Value.Fritolay, 300, 3.0));
        cachedItems.Add("Lays Sour Cream & Onion", new ItemFood("Lays Sour Cream & Onion", ItemMakerType.Value.Fritolay, 300, 3.0));
    }
    public static Item GetItem(string key)
    {
        if (cachedItems.Count == 0)
            LoadCachedItems();
        return cachedItems.ContainsKey(key) ? (Item)cachedItems[key].Clone() : null;
    }
}

IEatable.cs，IDrinkable.cs

public interface IEatable
{
    // Simple interface that demonstrates actions for a specifit set of objects (by object type).
    void Eat();
}
public interface IDrinkable
{
    // Simple interface that demonstrates actions for a specifit set of objects (by object type).
    void Drink();
}

Observer.cs，MachineScreenObserver.cs，MachineLoggerObserver.cs，ObserverCommands.cs

public interface Observer
{
    void Update(VendingMachineLog log);
}
public sealed class MachineScreenObserver : Observer
{
    public void Update(VendingMachineLog log)
    {
        Console.WriteLine("Machine Screen: {0}", log.LogMessage);
    }
}
public sealed class MachineLoggerObserver : Observer
{
    private List<VendingMachineLog> vendingMachineLogs;

    public MachineLoggerObserver()
    {
        this.vendingMachineLogs = new List<VendingMachineLog>();
    }

    public void PrintLastMachineLogs(int num)
    {
        foreach (VendingMachineLog log in vendingMachineLogs)
        {
            if (num-- > 0)
                return;

            Console.WriteLine(log);
        }
    }
    public void Update(VendingMachineLog log)
    {
        this.vendingMachineLogs.Add(log);
        Console.WriteLine("Machine Logger: {0}", log.LogMessage);
    }
}
public interface ObserverCommands
{
    void RegisterObserver(Observer observer);
    void UnregisterObserver(Observer observer);
    void NotifyAllObservers(VendingMachineLog log);
}

Record.cs，SaleRecord.cs

public abstract class Record
{
    protected readonly int recordID;
    protected readonly DateTime recordDate;
    protected readonly string recordMessage;

    public Record(int recordID, DateTime recordDate, string recordMessage)
    {
        this.recordID = recordID;
        this.recordDate = recordDate;
        this.recordMessage = recordMessage;
    }

    public int RecordID
    {
        get
        {
            return this.recordID;
        }
    }
    public DateTime RecordDate
    {
        get
        {
            return this.recordDate;
        }
    }
    public string RecordMessage
    {
        get
        {
            return this.recordMessage;
        }
    }
}
public sealed class SaleRecord : Record
{
    private static int totalSaleRecords = 0;

    private readonly Item saleItem;
    private readonly double amountPaid;

    public SaleRecord(DateTime recordDate, string recordMessage, Item saleItem, double amountPaid) :
        base(totalSaleRecords++, recordDate, recordMessage)
    {
        this.saleItem = saleItem;
        this.amountPaid = amountPaid;
    }

    public Item SaleItem
    {
        get
        {
            return this.saleItem;
        }
    }
    public double AmountPaid
    {
        get
        {
            return this.amountPaid;
        }
    }

    public override string ToString()
    {
        return string.Format("[Sale Record] ID: {0}, Date: {1}, Item Sold: {2}, Sale Amount: {3}",
            this.recordID, this.recordDate.ToString("dd/MM/yyyy HH:mm:ss"), this.saleItem.ItemName, this.saleItem.ItemPrice);
    }
}

VendingMachineLog.cs

public class VendingMachineLog
{
    private static int totalVendingMachineLogs = 0;

    protected readonly int logID;
    protected readonly DateTime logDate;
    protected readonly string logMessage;

    public VendingMachineLog(string logMessage)
    {
        this.logID = totalVendingMachineLogs++;
        this.logDate = DateTime.Now;
        this.logMessage = logMessage;
    } 
    public VendingMachineLog(DateTime logDate, string logMessage)
    {
        this.logID = totalVendingMachineLogs++;
        this.logDate = logDate;
        this.logMessage = logMessage;
    }

    public int LogID
    {
        get
        {
            return this.logID;
        }
    }
    public DateTime LogDate
    {
        get
        {
            return this.logDate;
        }
    }
    public string LogMessage
    {
        get
        {
            return this.logMessage;
        }
    }

    public override string ToString()
    {
        return string.Format("[Log] ID: {0}, Date: {1}, Message: {2}",
            this.logID, this.logDate.ToString("dd/MM/yyyy HH:mm:ss"), this.logMessage);
    }
}

Program.cs

class Program
{
    static VendingMachine vendingMachine;
    static void Main(string[] args)
    {
        vendingMachine = VendingMachine.GetInstance();
        vendingMachine.RegisterObserver(new MachineLoggerObserver());
        vendingMachine.RegisterObserver(new MachineScreenObserver());

        PrintColored("- Initialized Vending Machine.", ConsoleColor.Cyan);
        RequestUserAction();
    }
    static void RequestUserAction()
    {
        Console.WriteLine("What action would you like to use?\n1 - Print Machine Info, 2 - Print 5 Last Sale Records, 3 - Refill Machine, 4 - Purchase a Product\nHINT: Type EXIT to disconnect from the system.");
        string userInput = Console.ReadLine();
        switch (userInput)
        {
            case "1":
                PrintColored(vendingMachine.ToString(), ConsoleColor.Green);
                break;
            case "2":
                DisplaySaleRecords();
                break;
            case "3":
                vendingMachine.RefillItems();
                //
                break;
            case "4":
                ProductPurchase();
                break;
            case "EXIT":
                Environment.Exit(0);
                break;
            default:
                break;
        }
        RequestUserAction(); 
    }
    static void DisplaySaleRecords()
    {
        List<SaleRecord> saleRecords = vendingMachine.GetLastSaleRecords(5);

        if (saleRecords == null || saleRecords.Count == 0)
        {
            PrintColored("There are currently no sale records to present.", ConsoleColor.Red);
            return; ;
        }

        foreach(SaleRecord saleRecord in saleRecords)
            PrintColored(saleRecord.ToString(), ConsoleColor.DarkYellow);
    }
    static void ProductPurchase()
    {
        Item requestedItem = null;
        string userInputString = string.Empty;
        int userInputInt;
        double userInputDouble;

        if (vendingMachine.MachineItems.Count == 0)
        {
            PrintColored("[ERROR] This vending machine does not have any items in stock.", ConsoleColor.Red);
            return;
        }

        PrintColored("Select the item you would like to purchase (Item ID).", ConsoleColor.Cyan);
        Console.WriteLine("HINT: Type EXIT in order to return to the previous menu.");
        PrintColored("Available Machine Items:", ConsoleColor.Cyan);
        foreach (Item item in vendingMachine.MachineItems.Keys)
        {
            PrintColored(string.Format("{0} [IN STOCK: {1}]", item.ToString(), vendingMachine.MachineItems[item]), 
                ConsoleColor.DarkGreen);
        }

        userInputString = Console.ReadLine();

        if (userInputString == "EXIT")
            return;

        if (!int.TryParse(userInputString, out userInputInt))
        {
            PrintColored("[ERROR] Invalid input.", ConsoleColor.Red);
            ProductPurchase();
            return;
        }

        foreach (Item item in vendingMachine.MachineItems.Keys)
        {
            if (item.ItemID == userInputInt)
            {
                requestedItem = item;
                break;
            }
        }

        if (requestedItem == null)
        {
            PrintColored("[ERROR] No such item in the vending machine. Please try again.", ConsoleColor.Red);
            ProductPurchase();
            return;
        }

        if (vendingMachine.GetItemStock(requestedItem) == 0)
        {
            PrintColored("[ERROR] Item is out of stock.", ConsoleColor.Red);
            ProductPurchase();
            return;
        }

        Console.WriteLine(requestedItem);
        Console.WriteLine("How much money are you paying?");
        userInputString = Console.ReadLine();

        if (!Double.TryParse(userInputString, out userInputDouble))
        {
            PrintColored("[ERROR] Invalid input.", ConsoleColor.Red);
            ProductPurchase();
            return;
        }
        if (userInputDouble < requestedItem.ItemPrice)
        {
            PrintColored("[ERROR]  Item price is higher than the paid amount.", ConsoleColor.Red);
            ProductPurchase();
            return;
        }

        vendingMachine.SellItem(requestedItem, userInputDouble);

        string recordMessage = string.Format("[Vending Machine]: Item has been successfully sold (Paid: {0}, Returned: {1}).",
                userInputDouble.ToString("C"), (userInputDouble - requestedItem.ItemPrice).ToString("C"));

        SaleRecord saleRecord = new SaleRecord(DateTime.Now, recordMessage, requestedItem, userInputDouble);
        vendingMachine.AddSaleRecord(saleRecord);
        PrintColored(recordMessage, ConsoleColor.Green);
    }
    static void PrintColored(string text, ConsoleColor color)
    {
        Console.ForegroundColor = color;
        Console.WriteLine(text);
        Console.ResetColor();
    }
}

我试图使类方法尽可能简单，并在Program.cs中处理所有验证。我很高兴收到任何关于我的代码和写作风格的反馈。

.net

console

object-oriented

design-patterns

回答 1

Code Review用户

发布于 2017-03-31 20:06:22

我认为machineBank这个名字有误导性。例如，它可能是machineMoneySum。

顺便说一句，也许我们并不真正需要“机器”部分，因为我们已经在VendingMachine类中了。这也适用于其他属性。

当用负数(甚至为零)调用GetLastSaleRecords时，它真的应该返回null吗？如果您的一般原则是“我的方法只接受正确的论点”，那么抛出一个异常也许更合适。

在任何情况下，当返回类型是Collection时，通常建议在.NET中返回一个空的而不是null。积极的效果是，调用者将不需要麻烦地检查一个null在集合的情况下。

在Equals() of Item，而不是

castedItem = (Item)obj;

并且捕捉到异常，您可以简单地

castedItem = Item as obj;

并检查结果是否为null。

顺便说一句，我发现这样写Equals()是很不错的：

public override bool Equals(object obj)
{
    if (obj == null || GetType() != obj.GetType())
    {
        return false;
    }

    return Equals((Item)obj);
}

public bool Equals(Item item)
{
    return itemID == item.itemID;
}

这两个函数中的每一个都做了一件事。:)

第一个函数是转换中类型以外的所有类的标准函数。注意，我们知道这个强制转换是安全的，因为我们不久前检查了类型。

packCapacity和canCapacity在ItemFood和ItemDrink中的测量单位分别是什么？将其直接放在变量名(例如packCapacityGrams )或注释中，这是一个可读性加法。

票数 0

页面原文内容由Code Review提供。腾讯云小微IT领域专用引擎提供翻译支持

原文链接：

https://codereview.stackexchange.com/questions/158792

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相似问题

问自动售货机
EN

VendingMachine.cs

Item.cs，ItemFood.cs，ItemDrink.cs，ItemMakerType.cs

ItemFactory.cs

IEatable.cs，IDrinkable.cs

Observer.cs，MachineScreenObserver.cs，MachineLoggerObserver.cs，ObserverCommands.cs

Record.cs，SaleRecord.cs

VendingMachineLog.cs

Program.cs

回答 1

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问自动售货机EN

VendingMachine.cs

Item.cs，ItemFood.cs，ItemDrink.cs，ItemMakerType.cs

ItemFactory.cs

IEatable.cs，IDrinkable.cs

Observer.cs，MachineScreenObserver.cs，MachineLoggerObserver.cs，ObserverCommands.cs

Record.cs，SaleRecord.cs

VendingMachineLog.cs

Program.cs

回答 1

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问自动售货机
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