策略模式(Strategy)

UML類圖：

代碼示例：

[csharp]
//策略類  
public abstract class Animal 
{ 
    public abstract void Run(); 
} 
 
public class Dog : Animal 
{ 
    public override void Run() 
    { 
        Console.WriteLine("Dog was running..."); 
    } 
} 
 
public class Cat : Animal 
{ 
    public override void Run() 
    { 
        Console.WriteLine("Cat was running..."); 
    } 
} 
//Context類，維護一個Animal實例  
public class AnimalContext 
{ 
    public Animal AnimalInstance { get; set; } 
 
    public AnimalContext(Animal animal) 
    { 
        this.AnimalInstance = animal; 
    } 
} 

    //策略類
    public abstract class Animal
    {
        public abstract void Run();
    }

    public class Dog : Animal
    {
        public override void Run()
        {
            Console.WriteLine("Dog was running...");
        }
    }

    public class Cat : Animal
    {
        public override void Run()
        {
            Console.WriteLine("Cat was running...");
        }
    }
    //Context類，維護一個Animal實例
    public class AnimalContext
    {
        public Animal AnimalInstance { get; set; }

        public AnimalContext(Animal animal)
        {
            this.AnimalInstance = animal;
        }
    }

策略與簡單工廠結合：

[csharp]
//策略類  
public abstract class Animal 
{ 
    public abstract void Run(); 
} 
 
public class Dog : Animal 
{ 
    public override void Run() 
    { 
        Console.WriteLine("Dog was running..."); 
    } 
} 
 
public class Cat : Animal 
{ 
    public override void Run() 
    { 
        Console.WriteLine("Cat was running..."); 
    } 
} 
//Context類，維護一個Animal實例  
public class AnimalContext 
{ 
    public Animal AnimalInstance { get; set; } 
 
    public AnimalContext(string animalType)   //工廠類與Context類合並，構造函數參數string類型  
    { 
        switch(animalType) 
        { 
            case "Dog": 
                this.AnimalInstance = new Dog(); 
                break; 
            case "Cat": 
                this.AnimalInstance = new Cat(); 
                break; 
            default: 
                this.AnimalInstance = null; 
                break; 
        } 
    } 
} 

    //策略類
    public abstract class Animal
    {
        public abstract void Run();
    }

    public class Dog : Animal
    {
        public override void Run()
        {
            Console.WriteLine("Dog was running...");
        }
    }

    public class Cat : Animal
    {
        public override void Run()
        {
            Console.WriteLine("Cat was running...");
        }
    }
    //Context類，維護一個Animal實例
    public class AnimalContext
    {
        public Animal AnimalInstance { get; set; }

        public AnimalContext(string animalType)   //工廠類與Context類合並，構造函數參數string類型
        {
            switch(animalType)
            {
                case "Dog":
                    this.AnimalInstance = new Dog();
                    break;
                case "Cat":
                    this.AnimalInstance = new Cat();
                    break;
                default:
                    this.AnimalInstance = null;
                    break;
            }
        }
    }