public interface Flyweight {
    //一个示意性方法，参数state是外蕴状态
    public void operation(String state);
}

public class ConcreteFlyweight implements Flyweight {
    private Character intrinsicState = null;
    /**
     * 构造函数，内蕴状态作为参数传入
     * @param state
     */
    public ConcreteFlyweight(Character state){
        this.intrinsicState = state;
    }
    /**
     * 外蕴状态作为参数传入方法中，改变方法的行为，
     * 但是并不改变对象的内蕴状态。
     */
    @Override
    public void operation(String state) {
        // TODO Auto-generated method stub
        System.out.println("Intrinsic State = " + this.intrinsicState);
        System.out.println("Extrinsic State = " + state);
    }
}

public class FlyweightFactory {
    private Map<Character,Flyweight> files = new HashMap<Character,Flyweight>();
    public Flyweight factory(Character state){
        //先从缓存中查找对象
        Flyweight fly = files.get(state);
        if(fly == null){
            //如果对象不存在则创建一个新的Flyweight对象
            fly = new ConcreteFlyweight(state);
            //把这个新的Flyweight对象添加到缓存中
            files.put(state, fly);
        }
        return fly;
    }
}

public class Client {
    public static void main(String[] args) {
        FlyweightFactory factory = new FlyweightFactory();
        Flyweight fly = factory.factory(new Character('a'));
        fly.operation("First Call");
        fly = factory.factory(new Character('b'));
        fly.operation("Second Call");
        fly = factory.factory(new Character('a'));
        fly.operation("Third Call");
    }
}