享元模式

概念：运用共享技术有效地支持大量细粒度的对象
核心：共享内存，划分内部状态与外部状态，外部状态在使用的时候传递进来
作用：本地缓存

享元模式结构图

java代码

public class FlyWeightTest {
    public static void main(String[] args) {
        FlyWeightFactory f = new FlyWeightFactory();
        int index = 22;
        FlyWeight x = f.GetFlyWeight("X");
        x.Operation(index--);
        FlyWeight y = f.GetFlyWeight("Y");
        x.Operation(index--);
        FlyWeight z = f.GetFlyWeight("Z");
        x.Operation(index--);
        UnSharedConcreteFlyWeight unSharedConcreteFlyWeight = new UnSharedConcreteFlyWeight();
        unSharedConcreteFlyWeight.Operation(index--);
    }
}
//享元工厂
public class FlyWeightFactory {
    Map<String, FlyWeight> map = new HashMap<>();
    public FlyWeight GetFlyWeight(String key){
        return map.get(key);
    }
    public FlyWeightFactory(){
        map.put("X", new ConcreteFlyWeight());
        map.put("Y", new ConcreteFlyWeight());
        map.put("Z", new ConcreteFlyWeight());
    }
}
public abstract class FlyWeight {
    public abstract void Operation(int index);
}
public class UnSharedConcreteFlyWeight extends FlyWeight {
    @Override
    public void Operation(int index) {
        System.out.println("不共享的类" + index);
    }
}
public class ConcreteFlyWeight extends FlyWeight {
    @Override
    public void Operation(int index) {
        System.out.println("共享的类" + index);
    }
}