C# 設計模式：建造者模式完整指南（三）— 交通工具構建實戰範例

編輯：關於C語言

實戰場景

商店 (Shop) 使用不同車輛建造者 (VehicleBuilder) 依序構建車架、引擎、車輪、車門，產出機車、汽車、速克達。

完整代碼實作


using System;
using System.Collections;

// 指導者
class Shop
{
    public void Construct(VehicleBuilder vb)
    {
        vb.BuildFrame();
        vb.BuildEngine();
        vb.BuildWheels();
        vb.BuildDoors();
    }
}

// 抽象建造者
abstract class VehicleBuilder
{
    protected Vehicle vehicle;
    public Vehicle Vehicle => vehicle;

    public abstract void BuildFrame();
    public abstract void BuildEngine();
    public abstract void BuildWheels();
    public abstract void BuildDoors();
}

// 具體建造者：機車
class MotorCycleBuilder : VehicleBuilder
{
    public override void BuildFrame()
    {
        vehicle = new Vehicle("MotorCycle");
        vehicle["frame"] = "MotorCycle Frame";
    }
    public override void BuildEngine() => vehicle["engine"] = "500 cc";
    public override void BuildWheels() => vehicle["wheels"] = "2";
    public override void BuildDoors() => vehicle["doors"] = "0";
}

// 具體建造者：汽車
class CarBuilder : VehicleBuilder
{
    public override void BuildFrame()
    {
        vehicle = new Vehicle("Car");
        vehicle["frame"] = "Car Frame";
    }
    public override void BuildEngine() => vehicle["engine"] = "2500 cc";
    public override void BuildWheels() => vehicle["wheels"] = "4";
    public override void BuildDoors() => vehicle["doors"] = "4";
}

// 具體建造者：速克達
class ScooterBuilder : VehicleBuilder
{
    public override void BuildFrame()
    {
        vehicle = new Vehicle("Scooter");
        vehicle["frame"] = "Scooter Frame";
    }
    public override void BuildEngine() => vehicle["engine"] = "none";
    public override void BuildWheels() => vehicle["wheels"] = "2";
    public override void BuildDoors() => vehicle["doors"] = "0";
}

// 產品
class Vehicle
{
    private string type;
    private Hashtable parts = new Hashtable();

    public Vehicle(string type) => this.type = type;
    public object this[string key]
    {
        get => parts[key];
        set => parts[key] = value;
    }

    public void Show()
    {
        Console.WriteLine(" ---------------------------");
        Console.WriteLine($"Vehicle Type: {type}");
        Console.WriteLine($" Frame : {parts["frame"]}");
        Console.WriteLine($" Engine : {parts["engine"]}");
        Console.WriteLine($" #Wheels: {parts["wheels"]}");
        Console.WriteLine($" #Doors : {parts["doors"]}");
    }
}

// 客戶端
public class BuilderApp
{
    public static void Main()
    {
        Shop shop = new Shop();
        VehicleBuilder b1 = new ScooterBuilder();
        VehicleBuilder b2 = new CarBuilder();
        VehicleBuilder b3 = new MotorCycleBuilder();

        shop.Construct(b1); b1.Vehicle.Show();
        shop.Construct(b2); b2.Vehicle.Show();
        shop.Construct(b3); b3.Vehicle.Show();
    }
}

執行結果

 ---------------------------
Vehicle Type: Scooter
 Frame : Scooter Frame
 Engine : none
 #Wheels: 2
 #Doors : 0

 ---------------------------
Vehicle Type: Car
 Frame : Car Frame
 Engine : 2500 cc
 #Wheels: 4
 #Doors : 4

 ---------------------------
Vehicle Type: MotorCycle
 Frame : MotorCycle Frame
 Engine : 500 cc
 #Wheels: 2
 #Doors : 0