学步园

享元模式(Flyweight pattern)也被称作“轻量级模式”。

享元模式的主要目的是减少系统中重复对象的数量，在一定程度上降低内存消耗，提高系统运行速度。

当系统中需要创建多个对象，且这些对象可以在同一时间被多个线程共享的时候，可以考虑使用享元模式。

It can greatly improve performance if equivalent objects are requested often, especially if they are expensive to create.

Ps:单例模式为只创建一个对象实例，而享元模式是尽可能的减少重复的对象，最终所产生的实例对象不止一个。

Eg:

import java.util.HashMap;<br /> import java.util.Map;<br /> public class FlyweightFactory {</p> <p> private static FlyweightFactory S_INSTANCE = new FlyweightFactory();<br /> private static Map flyweightsPool = new HashMap();<br /> public static FlyweightFactory getInstance(){<br /> return S_INSTANCE;<br /> }<br /> public Flyweight getFlyweight(String a, String b){<br /> Flyweight flyweight = null;<br /> if(flyweightsPool.get(a+b) == null){<br /> flyweight = new Flyweight(a ,b);<br /> flyweightsPool.put((a+b), flyweight);<br /> }else{<br /> flyweight = (Flyweight)flyweightsPool.get(a+b);<br /> }<br /> return flyweight;<br /> }<br /> }

public class Flyweight {<br /> private String a;<br /> private String b;<br /> public Flyweight(String a, String b){<br /> this.a = a;<br /> this.b = b;<br /> }<br /> public String getA() {<br /> return a;<br /> }<br /> public void setA(String a) {<br /> this.a = a;<br /> }<br /> public String getB() {<br /> return b;<br /> }<br /> public void setB(String b) {<br /> this.b = b;<br /> }<br /> }<br />