设计模式 之 享元模式

和String达到一样的目的，节省空间

package com.test.pattern.flyweight;

import java.util.Hashtable;

abstract class Flyweight {
    public abstract void operation();
}

class ConcreteFlyweight extends Flyweight {
    
    private String str;
    public ConcreteFlyweight(String str) {
        this.str=str;
    }
    @Override
    public void operation() {
        System.out.println("Concrete---Flyweight: "+str);
    }
}

//再定义一个工厂方法类
class FlyweightFactory {
    private Hashtable flyweights = new Hashtable();
    public Flyweight getFlyweight(Object obj) {
        Flyweight flyweight = (Flyweight)flyweights.get(obj);
        if(flyweight == null) {
            flyweight = new ConcreteFlyweight((String) obj);
            flyweights.put(obj, flyweight);
        }
        return flyweight;
    }
    public int getFlyweightSize() {
        return flyweights.size();
    }
}
public class FlyweightTest {
    FlyweightFactory factory = new FlyweightFactory();
    Flyweight fly1,fly2,fly3,fly4,fly5;
    public static void main(String[] args) {
        System.out.println("The Flyweight Pattern");
        FlyweightTest test = new FlyweightTest();
        test.showFlyweight();
    }
    public FlyweightTest() {
        fly1 = factory.getFlyweight("Google");
        fly2 = factory.getFlyweight("Qutr");
        fly3 = factory.getFlyweight("Google");
        fly4 = factory.getFlyweight("Google");
        fly5 = factory.getFlyweight("Google");
    }
    public void showFlyweight() {
        fly1.operation();
        fly2.operation();
        fly3.operation();
        fly4.operation();
        fly5.operation();
        int objSize = factory.getFlyweightSize();
        System.out.println("objSize = " + objSize);
    }
}