.Net 几种常用设计模式【工厂、单例】

抽象工厂模式
// 抽象产品
public interface IProduct
{
    void Operation();
}

// 具体产品A
public class ProductA : IProduct
{
    public void Operation()
    {
        Console.WriteLine("Product A Operation");
    }
}

// 具体产品B
public class ProductB : IProduct
{
    public void Operation()
    {
        Console.WriteLine("Product B Operation");
    }
}

// 抽象工厂
public interface IFactory
{
    IProduct CreateProduct();
}

// 具体工厂A
public class FactoryA : IFactory
{
    public IProduct CreateProduct()
    {
        return new ProductA();
    }
}

// 具体工厂B
public class FactoryB : IFactory
{
    public IProduct CreateProduct()
    {
        return new ProductB();
    }
}

// 客户端
public class Client
{
    private IFactory factory;

    public Client(IFactory factory)
    {
        this.factory = factory;
    }

    public void Run()
    {
        IProduct product = factory.CreateProduct();
        product.Operation();
    }
}

// 使用示例
IFactory factoryA = new FactoryA();
Client clientA = new Client(factoryA);
clientA.Run();

IFactory factoryB = new FactoryB();
Client clientB = new Client(factoryB);
clientB.Run();

简单工厂模式
// 抽象产品
public interface IProduct
{
    void Operation();
}

// 具体产品A
public class ProductA : IProduct
{
    public void Operation()
    {
        Console.WriteLine("Product A Operation");
    }
}

// 具体产品B
public class ProductB : IProduct
{
    public void Operation()
    {
        Console.WriteLine("Product B Operation");
    }
}

// 工厂
public class SimpleFactory
{
    public IProduct CreateProduct(string type)
    {
        switch (type)
        {
            case "A":
                return new ProductA();
            case "B":
                return new ProductB();
            default:
                throw new ArgumentException("Invalid product type");
        }
    }
}

// 客户端
public class Client
{
    private SimpleFactory factory;

    public Client(SimpleFactory factory)
    {
        this.factory = factory;
    }

    public void Run()
    {
        IProduct product = factory.CreateProduct("A");
        product.Operation();
    }
}

// 使用示例
SimpleFactory simpleFactory = new SimpleFactory();
Client client = new Client(simpleFactory);
client.Run();

单例模式
public sealed class Singleton
{
    private static readonly Singleton instance = new Singleton();

    private Singleton()
    {
    }

    public static Singleton Instance
    {
        get
        {
            return instance;
        }
    }

    public void Operation()
    {
        Console.WriteLine("Singleton Operation");
    }
}

// 客户端
public class Client
{
    public void Run()
    {
        Singleton instance = Singleton.Instance;
        instance.Operation();
    }
}

// 使用示例
Client client = new Client();
client.Run();