深入理解Java设计模式之策略模式

//Strategy类，定义所有支持的算法的公共接口
abstract class Strategy
{
    //算法方法
    public abstract void AlgorithmInterface();
}

//算法A
    class ConcreteStrategyA : Strategy
    {
        public override void AlgorithmInterface()
        {
            Console.WriteLine("算法A的实现");
        }
    }
    //算法B
    class ConcreteStrategyB : Strategy
    {
        public override void AlgorithmInterface()
        {
            Console.WriteLine("算法B的实现");
        }
    }
    //算法C
    class ConcreteStrategyC : Strategy
    {
        public override void AlgorithmInterface()
        {
            Console.WriteLine("算法C的实现");
        }
    }

//Context，用一个ConcreteStrategy来配置，维护一个对Strategy对象的引用
    class Context
    {
        Strategy Strategy;
        public Context(Strategy Strategy)
        {
            this.Strategy = Strategy;
        }
        //上下文接口
        public void ContextInterface()
        {
            Strategy.AlgorithmInterface();
        }
    }

static void Main(string[] args)
        {
            Context Context;

            Context = new Context(new ConcreteStrategyA());
            Context.ContextInterface();

            Context = new Context(new ConcreteStrategyB());
            Context.ContextInterface();

            Context = new Context(new ConcreteStrategyC());
            Context.ContextInterface();

            Console.Read();
        }

class Context
    {
        Strategy Strategy=null;
        public Context(string type)
        {
            switch (type)
            {
                case "A":
                    ConcreteStrategyA A = new ConcreteStrategyA();
                    Strategy = A;
                    break;
                case "B":
                    ConcreteStrategyB B = new ConcreteStrategyB();
                    Strategy = B;
                    break;
                case "C":
                    ConcreteStrategyC C = new ConcreteStrategyC();
                    Strategy = C;
                    break;
            }
        }
        //上下文接口
        public void ContextInterface()
        {
            Strategy.AlgorithmInterface();
        }
    }

static void Main(string[] args)
        {
            Context Context = new Context("这里是相应的算法类型字符串");
            Context.ContextInterface();

            Console.Read();
        }

public enum Calculator 
{    ADD("+") {        
        public int exec(int a, int b) {    
            return a+b;        
        }
    },        
    SUB("-") {        
        public int exec(int a, int b) {        
            return a-b;        
            }    
    };            
    public abstract int exec(int a, int b);        
    //运算符    
    private String value = "";        
    private Calculator(String value)
    {        
        this.value = value;
    }     
    public String getValue() 
    {        
        return value;
    }
}