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轻量级的对象池-享元模式

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Words count in article: 320 字 | Reading time ≈ 2 分钟

享元模式又称Flyweight，代表轻量级的意思，适用于可能存在大量可重复对象的场景

这里举一个售卖火车票的例子

共享对象的接口，这里是火车票接口

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public interface Ticket {
    void showTicketInfo(String bunk);
}

具体对象类

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public class TrainTicket implements Ticket {
    public String from;
    public String to;
    public String bunk;
    public int price;
    public TrainTicket(String from, String to) {
        this.from = from;
        this.to = to;
        price = new Random().nextInt(300);
    }
    @Override
    public void showTicketInfo(String bunk) {
        System.out.println(from + "到" + to + "的" + bunk +"火车票价格：" + price);
    }
}

对象生产工厂

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public class TickFactory {
    static Map<String, Ticket> stringTicketMap = new ConcurrentHashMap<>();
    public static Ticket getTicket(String from, String to) {
        String key = from + "-" + to;
        if (stringTicketMap.containsKey(key)) {
            return stringTicketMap.get(key);
        } else {
            Ticket ticket =new TrainTicket(from, to);
            stringTicketMap.put(from + "-" + to,ticket);
            return ticket;
        }
    }
}

在这里我们使用了一个map来存放已经存在的对象，这也是享元模式的关键，这样就不用每次都重新创建对象，减少内存的消耗

使用如下

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public class Main {
    public static void main(String[] args) {
        Ticket ticket = TickFactory.getTicket("长兴", "武汉");
        ticket.showTicketInfo("上铺");
        Ticket ticket1 = TickFactory.getTicket("武汉", "长兴");
        ticket1.showTicketInfo("软卧");
        Ticket ticket2 = TickFactory.getTicket("长兴", "武汉");
        ticket2.showTicketInfo("上铺");
    }
}

结果

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