Flyweight

享元模式以共享的方式高效地支持大量的细粒度对象.

1).FlyweightDemo.java

 

package com.flyingh.demo;

public class FlyweightDemo {
	public static void main(String[] args) {
		String str1 = "abc";
		String str2 = "a" + "bc";
		String str3 = "abc";
		String str4 = str3 + "";
		final String str5 = "ab";
		System.out.println(str1 == str2);
		System.out.println(str2 == str3);
		System.out.println(str3 == str4);
		str4 = str5 + "c";
		System.out.println(str3 == str4);
		System.out.println("*********");
		Integer i1 = 3;
		Integer i2 = 3;
		Integer i3 = 1 + 2;
		System.out.println(i1 == i2);
		System.out.println(i2 == i3);
		System.out.println("*********");
		Long l1 = 127l;
		Long l2 = 127l;
		System.out.println(l1 == l2);
	}
}

 程序运行结果如下：

 

true
true
false
true
*********
true
true
*********
true

 2).假设有许许多多的Athlete进行比赛，他们按Key(包含age,sex,weight)分组进行比赛,即使分组后每组也有许许多多的Athlete：

Key.java

package com.flyingh.vo;

public class Key {
	private int age;
	private Sex sex;
	private float weight;

	public Key(int age, Sex sex, float weight) {
		super();
		this.age = age;
		this.sex = sex;
		this.weight = weight;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public Sex getSex() {
		return sex;
	}

	public void setSex(Sex sex) {
		this.sex = sex;
	}

	public float getWeight() {
		return weight;
	}

	public void setWeight(float weight) {
		this.weight = weight;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + age;
		result = prime * result + ((sex == null) ? 0 : sex.hashCode());
		result = prime * result + Float.floatToIntBits(weight);
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Key other = (Key) obj;
		if (age != other.age)
			return false;
		if (sex != other.sex)
			return false;
		if (Float.floatToIntBits(weight) != Float.floatToIntBits(other.weight))
			return false;
		return true;
	}

	@Override
	public String toString() {
		return "[age=" + age + ", sex=" + sex + ", weight=" + weight + "]";
	}
	
}

Athlete.java

package com.flyingh.vo;

public class Athlete {
	private Key key;

	public Athlete(Key key) {
		super();
		this.key = key;
	}

	public Key getKey() {
		return key;
	}

	public void setKey(Key key) {
		this.key = key;
	}

	public void setName(String name) {
		System.out.println("名字为：" + name);
	}

}

 Sex.java

package com.flyingh.vo;

public enum Sex {
	man, woman;
}

 AthleteFactory.java

package com.flyingh.pool;

import java.util.HashMap;
import java.util.Map;

import com.flyingh.vo.Key;
import com.flyingh.vo.Athlete;

public class AthleteFactory {
	private static Map<Key, Athlete> map = new HashMap<Key, Athlete>();

	public static Athlete getAthlete(Key key) {
		if (map.containsKey(key)) {
			System.out.println(key + "已经存在！");
			return map.get(key);
		} else {
			System.out.println(key + "不存在，创建后放入Pool！");
			Athlete person = new Athlete(key);
			map.put(key, person);
			return person;
		}
	}
}

 Client.java

package com.flyingh.client;

import com.flyingh.pool.AthleteFactory;
import com.flyingh.vo.Key;
import com.flyingh.vo.Athlete;
import com.flyingh.vo.Sex;

public class Client {
	public static void main(String[] args) {
		Key key1 = new Key(18, Sex.man, 60);
		Key key2 = new Key(20, Sex.woman, 55);
		Athlete zhangsan = AthleteFactory.getAthlete(key1);
		zhangsan.setName("张三");
		Athlete lisi = AthleteFactory.getAthlete(key1);
		lisi.setName("李四");
		Athlete wangwu = AthleteFactory.getAthlete(key2);
		wangwu.setName("王五");
		Athlete zhaoliu = AthleteFactory.getAthlete(new Key(18, Sex.man, 60));
		zhaoliu.setName("赵六");
	}
}

 程序运行结果如下：

[age=18, sex=man, weight=60.0]不存在，创建后放入Pool！
名字为：张三
[age=18, sex=man, weight=60.0]已经存在！
名字为：李四
[age=20, sex=woman, weight=55.0]不存在，创建后放入Pool！
名字为：王五
[age=18, sex=man, weight=60.0]已经存在！
名字为：赵六