享元模式

类似单例模式

public abstract class Web {
abstract void use(String type);
}

public class ConcreteWeb extends Web {
    String type;

    public ConcreteWeb(String type) {
        this.type = type;
    }

    @Override
    void use(String type) {
        System.out.println("这个网站的类型是：" + type);
    }
}

public class WebFactory {
    Map<String,ConcreteWeb> map=new HashMap<>();
    public ConcreteWeb getWeb(String web){
        if (!map.containsKey(web)){
            map.put(web,new ConcreteWeb(web));
            return map.get(web);
        }else {
            return map.get(web);
        }
    }
    public int getSize(){
        return map.size();
    }
}

测试

public class Test {
    public static void main(String[] args) {
        WebFactory webFactory = new WebFactory();
        webFactory.getWeb("yule");
        webFactory.getWeb("wenyi");
        System.out.println(webFactory.getSize());
        webFactory.getWeb("yule");
        System.out.println(webFactory.getSize());
    }
}