设计模式之策略模式

策略模式+单例+工厂解决if else问题

例如：if(情况一){业务一}；

           else if(情况二){业务二}；

           else if(情况三){业务三}； 

解决方案：

       public interface strategy

        {

                public void methods(sring situation){}；

        }

        public void oneStrategy implementation strategy

        {

                @override

                public void methods(sring situation){业务一}；

        }

       public void twoStrategy implementation strategy

        {

                @override

                public void methods(sring situation){业务二}；

        }

       public void threeStrategy implementation strategy

        {

                @override

                public void methods(sring situation){业务三}；

        }

public class strategyFactory

{

        static Map<string, strategy> map = new map<string, strategy>()

        { {情况一，new oneStrategy()  }，   {情况二，new twoStrategy() }，   {情况三，new threeStrategy() } }

        private static classs strategyFactoryHolder

        {

                private static final strategyFactory instance = new strategyFactory();

        }

        public strategyFactory getInstance()

        {

                return  strategyFactory.instance;

        }

        public strategyFactory getStrategy(stirng situation)

        {

                return  map.get(situation);

        }

}

public static void test(stirng situation)

{

       strategy s =  strategyFactory.getInstance.getStrategy(stirng situation);

        if( s == null)

        {

                return;

        }

         s .methods(stirng situation);

}