策略模式

今天研究一下策略模式。

示例程序如下：

Strategy.cs

namespace StrategyPatternExample
{
    public interface Strategy
    {
        int Execute(int a, int b);
    }
}

Context.cs

namespace StrategyPatternExample
{
    public class Context
    {
        private Strategy strategy;

        public Context(Strategy strategy)
        {
            this.strategy = strategy;
        }

        public int ExecuteStrategy(int a, int b)
        {
            return strategy.Execute(a, b);

        }
    }
}

ConcreteStrategyAdd.cs

using System;

namespace StrategyPatternExample
{
    class ConcreteStrategyAdd : Strategy
    {
        public int Execute(int a, int b)
        {

            Console.WriteLine("Called ConcreateStrategyAdd's execute. a = {0}, b = {1}", a, b);
            return a + b;
        }


    }
}

ConcreteStrategySubtract.cs

using System;

namespace StrategyPatternExample
{
    class ConcreteStrategySubtract:Strategy
    {
        public int Execute(int a, int b)
        {
            Console.WriteLine("Called ConcreteStrategySubtract's execute, a = {0}, b = {1}",a, b);
            return a - b;
        }
    }
}

Program.cs

using System;

namespace StrategyPatternExample
{
    class Program
    {
        static void Main(string[] args)
        {
            Context context;

            context = new Context(new ConcreteStrategySubtract());
            int resultSub = context.ExecuteStrategy(2, 1);
            Console.WriteLine("ConcreteStrategySubtract's result is {0}", resultSub);
            Console.WriteLine();

            context = new Context(new ConcreteStrategyAdd());
            int resultAdd = context.ExecuteStrategy(3, 4);
            Console.WriteLine("ConcreteStrategyAdd's result is {0}", resultAdd);
        }
    }
}

result：