享元模式

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设计模式/结构型设计模式

简述

以共享的方式高效地支持大量细粒度对象的重用

UML图

代码

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@Slf4j
public abstract class Bird implements Animal {
    @Override
    public void run() {
        log.debug(“抽象鸟类—“);
    }
}

@Slf4j
@Getter
public class Penguin extends Bird {
    private String name;        // 名字
    @Setter
    @Getter
    private String color;       // 颜色

    public Penguin(String name) {
        this.name = name;
    }

    @Override
    public void run() {
        log.debug("企鹅-- " + name + "  " + color);
    }
}

public class FlyweightFactory {

    private static final HashMap<String, Bird> pool = new HashMap();

    public static Bird getInstance(String name) {
        Bird bird = null;
        if (pool.containsKey(name)) {
            bird = pool.get(name);
        } else {
            bird = new Penguin(name);
            ((Penguin) bird).setColor("黑色");
            pool.put(name, bird);
        }
        return bird;
    }

    public static int size() {
        return pool.size();
    }
}

@Slf4j
public class Client {
    public static void main(String[] args) {
        Bird white = FlyweightFactory.getInstance(“penguin”);
        ((Penguin) white).setColor("白色");
        Bird orange = FlyweightFactory.getInstance("penguin");
        ((Penguin) orange).setColor("橘色");
        Bird king = FlyweightFactory.getInstance("king");
        log.debug("size: " + FlyweightFactory.size());
    }
}