设计模式笔记---享元模式

1、概念

是池技术的重要实现方式，使用共享对象可有效地支持大量的细粒度的对象。

2、说明

Flyweight：抽象享元角色（一个产品的抽象类，同时定义出对象的外部状态和内部状态的接口或实现）

public abstract class Flyweight {
    private String intrinsic;

    protected  final String extrinstic;

    public Flyweight(String _extrinstic){
        this.extrinstic = _extrinstic;
    }

    public  abstract void operate();

    public String getIntrinsic() {
        return intrinsic;
    }

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

ConcreFlyweight：具体享元单元（具体的一个产品类，实现抽象角色定义的义务）

public class ConcreFlyweight1 extends Flyweight {
    public ConcreFlyweight1(String _extrinstic) {
        super(_extrinstic);
    }

    @Override
    public void operate() {

    }
}

FlyweightFactory：享元工厂（构造一个池容器，同时提供从池中获得对象的方法）

public class FlyweightFactory {
    private static HashMap<String,Flyweight> pool = new HashMap<String, Flyweight>();

    public static Flyweight getFlyweight(String extrinstic){
        Flyweight flyweight = null;

        if(pool.containsKey(extrinstic)){
            flyweight = pool.get(extrinstic);
        }else{
            flyweight = new ConcreFlyweight1(extrinstic);
            pool.put(extrinstic,flyweight);
        }

        return flyweight;
    }
}

场景类：

public class Client {
    public static void main(String args[]){
        Integer times = 1000000000;
        String key = "test";
        FlyweightFactory.getFlyweight(key);

        Long t1 = System.currentTimeMillis();
        for(int i=0;i<times;i++){
            Flyweight flyweight = new ConcreFlyweight1(key);
        }
        Long t2 = System.currentTimeMillis();
        System.out.println("create time 1:"+(t2-t1));

        Long t3 = System.currentTimeMillis();
        for(int i=0;i<times;i++){
            FlyweightFactory.getFlyweight(key);
        }
        Long t4 = System.currentTimeMillis();
        System.out.println("create time 2:"+(t4-t3));
    }
}

输出结果：

create time 1:491
create time 2:4199

 

3.特点

优点：大大减少应用程序创建的对象，降低程序内存的占用，增强程序的性能

缺点：提高了系统复杂性；工厂类创建对象时间变长

本文地址：https://blog.csdn.net/qq_39961073/article/details/110248415