享元模式（Flyweight）_java实现

//20210120
写在前面：刚期末考试完，考了面向对象，里边儿有23个设计模式，我寻思着考完挨个儿实现一下，本文实现适配者模式

核心思想

• 如果在一个类中频繁创建内容相同的对象，则会使内存占用很高，如果在产品中使用此方法，则会占用大量内存，如果将内容相同的对象共享，则能够节省很多资源，享元模式应运而生，正如其名，它提供可共享的对象

程序源代码如下：

//享元抽象父类
public abstract class FlyWeight {
    //内部状态
    public String intrinsic;
    //外部状态
    protected final String extrinsic;

    //要求享元角色必须接受外部状态
    public FlyWeight(String extrinsic){
        this.extrinsic = extrinsic;
    }

    //定义业务操作
    public abstract void operate (int extrinsic);

    public String getIntrinsic(){
        return intrinsic;
    }

    public void setIntrinsic(String intrinsic){
        this.intrinsic = intrinsic;
    }
}

//具体享元（继承父类）

public class ConcreteFlyWeight extends FlyWeight{

    //接受外部状态
    public ConcreteFlyWeight(String extrinsic){
        super(extrinsic);
    }

    //根据外部状态进行逻辑处理

    @Override
    public void operate(int extrinsic) {
        System.out.println("具体FlyWeight："+ extrinsic);
    }
}

//非共享享元
public class UnsharedConcreteFlyWeight extends FlyWeight{
    public UnsharedConcreteFlyWeight(String extrinsic){
        super(extrinsic);
    }

    @Override
    public void operate(int extrinsic) {
        System.out.println("不共享的具体FlyWeight："+extrinsic);
    }
}

//享元工厂
public class FlyWeightFactory {
    //定义一个池容器
    private static HashMap<String ,FlyWeight> pool = new HashMap<>();

    //享元工厂
    public static FlyWeight getFlyWeight(String extrinsic){
        FlyWeight flyWeight = null;
        if(pool.containsKey(extrinsic)){//如果池中有该对象
            flyWeight = pool.get(extrinsic);
            System.out.print("已有"+extrinsic+" 直接从池中取----->");
        } else {
            //根据外部状态创建享元对象
            flyWeight = new ConcreteFlyWeight(extrinsic);
            //放入池中
            pool.put(extrinsic,flyWeight);
            System.out.print("创建" + extrinsic + " 并从池中取出----->");
        }
        return flyWeight;//工厂生产出一个享元
    }
}

//测试主类
public class Main {
    public static void main(String[] args) {
        int extrinsic = 22;

        FlyWeight flyWeight_1 = FlyWeightFactory.getFlyWeight("X");
        flyWeight_1.operate(++extrinsic);

        FlyWeight flyWeight_2 = FlyWeightFactory.getFlyWeight("Y");
        flyWeight_2.operate(++extrinsic);

        FlyWeight flyWeight_3 = FlyWeightFactory.getFlyWeight("Z");
        flyWeight_3.operate(++extrinsic);

        FlyWeight flyWeight_re_1 = FlyWeightFactory.getFlyWeight("X");
        flyWeight_re_1.operate(++extrinsic);

        FlyWeight unshareFlyWeight = new UnsharedConcreteFlyWeight("X");
        unshareFlyWeight.operate(++extrinsic);
    }
}

• 输出如下
  

以上
希望对大家有所帮助