n个妙计，一个锦囊。

妙计接口

public interface IStrategy{
        public void operate();
    }

具体妙计实现类

public class Strategy1 implements IStrategy{
        @Override
        public void operate(){
            System.out.println("妙计1");
        }
    }
    public class Strategy2 implements IStrategy{
        @Override
        public void operate(){
            System.out.println("妙计2");
        }
    }

一个锦囊，通过锦囊取出具体妙计,并使用。

public class Context{
        private IStrategy strategy;
        public Context(IStrategy strategy){
            this.strategy = strategy;
        }
        public void operate(){
            this.strategy.operate();
        }
    }