参考文档：
1.设计模式书籍；
2.http://blog.csdn.net/hguisu/article/details/7535792（设计模式（十）享元模式Flyweight（结构型））
3.http://www.jdon.com/designpatterns/flyweight.htm（设计模式之Flyweight(享元) FlyWeight模式）
Flyweight理论方面的知识，可以查看参考文档中的两篇博客；
我这里，使用Flyweight实现了两个案例，欢迎拍砖；
案例1（来自参考文档3）：
以唱片CD为例,在一个XML文件中,存放了多个CD的资料.
每个CD有三个字段: 1.出片日期(year) 2.歌唱者姓名等信息(artist) 3.唱片曲目 (title)
其中,歌唱者姓名有可能重复,也就是说,可能有同一个演唱者的多个不同时期 不同曲目的CD.我们将"歌唱者姓名"作为可共享的ConcreteFlyweight.其他两个字段作为UnsharedConcreteFlyweight.
<?xml version="1.0"?> <collection> <cd> <title>Another Green World</title> <year>1978</year> <artist>Eno, Brian</artist> </cd> <cd> <title>Greatest Hits</title> <year>1950</year> <artist>Holiday, Billie</artist> </cd> <cd> <title>Taking Tiger Mountain (by strategy)</title> <year>1977</year> <artist>Eno, Brian</artist> </cd> ....... </collection> 代码实现： Client.java: package com.rick.designpattern.flyweight2; /** * Created by MyPC on 2017/6/7. */ public class Client { /*** * * * <?xml version="1.0"?> <collection> <cd> <title>Another Green World</title> <year>1978</year> <artist>Eno, Brian</artist> </cd> <cd> <title>Greatest Hits</title> <year>1950</year> <artist>Holiday, Billie</artist> </cd> <cd> <title>Taking Tiger Mountain (by strategy)</title> <year>1977</year> <artist>Eno, Brian</artist> </cd> ....... </collection> * * */ public static void main(String[] args) { ArtistFactory factory = new ArtistFactory(); CD cd = new CD("Another Green World","1978",factory.getFlyweights("Eno, Brian")); } } CD.java:package com.rick.designpattern.flyweight2; /** * Created by MyPC on 2017/6/7. */ public class CD { private String title; private String year; private Artist artist; public CD() { } public CD(String title, String year, Artist artist) { this.title = title; this.year = year; this.artist = artist; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getYear() { return year; } public void setYear(String year) { this.year = year; } public Artist getArtist() { return artist; } public void setArtist(Artist artist) { this.artist = artist; } } Artist.java:package com.rick.designpattern.flyweight2; /** * Created by MyPC on 2017/6/7. */ public class Artist { //内部状态 private String name; public Artist() { } public Artist(String name) { this.name = name; } public String getName() { return name; } public void setName(String name) { this.name = name; } } ArtistFactory.java:package com.rick.designpattern.flyweight2; import java.util.Hashtable; /** * Created by MyPC on 2017/6/7. */ public class ArtistFactory { private Hashtable<String, Artist> flyweights = new Hashtable(); public Artist getFlyweights(String key) { Artist artist = (Artist) flyweights.get(key); if (null == artist) { artist = new Artist(key); flyweights.put(key, artist); } return artist; } }案例2（参考文档2的复合享元模式案例）：
Client.java: package com.rick.designpattern.flyweight3; /** * Created by MyPC on 2017/6/7. */ public class Client { public static void main(String[] args){ FlyweightFactory flyweightFactory = new FlyweightFactory(); Flyweight flyweight= flyweightFactory.getFlyweight("A"); flyweight.operation("a"); Flyweight flyweight1 = flyweightFactory.getFlyweight("B"); flyweight1.operation("b"); UnsharedConcreteFlyweight unsharedConcreteFlyweight = (UnsharedConcreteFlyweight) flyweightFactory.getFlyweight(new String[]{"C","D"}); unsharedConcreteFlyweight.operation("c,d"); } } FlyweightFactory.java: package com.rick.designpattern.flyweight3; import java.lang.reflect.Array; import java.util.Hashtable; import java.util.List; import java.util.Set; /** * Created by MyPC on 2017/6/7. */ public class FlyweightFactory { private Hashtable<Object, ConcreteFlyweight> flyweights = new Hashtable<Object, ConcreteFlyweight>(); public Flyweight getFlyweight(Object state) { if (state instanceof String[]) { UnsharedConcreteFlyweight unsharedConcreteFlyweight = new UnsharedConcreteFlyweight(); String[] list = (String[]) state; for (Object obj : list) { unsharedConcreteFlyweight.add(getFlyweight(obj)); } return unsharedConcreteFlyweight; } else if (state instanceof String) { ConcreteFlyweight concreteFlyweight = flyweights.get(state); if (null == concreteFlyweight) { concreteFlyweight = new ConcreteFlyweight(state); flyweights.put(state, concreteFlyweight); } return concreteFlyweight; } else { return null; } } } Flyweight.java:package com.rick.designpattern.flyweight3; /** * Created by MyPC on 2017/6/7. */ public interface Flyweight { public void operation(Object state); } ConcreteFlyweight.java:package com.rick.designpattern.flyweight3; /** * 具体享元角色 */ public class ConcreteFlyweight implements Flyweight { private String intrinsicState; public ConcreteFlyweight(Object state) { this.intrinsicState = String.valueOf(state); } @Override public void operation(Object state) { System.out.println("ConcreteFlyweight operation, Intrinsic State = " + intrinsicState + "; Extrinsic State = " + String.valueOf(state) + ";<br />"); } } UnsharedConcreteFlyweight.java:package com.rick.designpattern.flyweight3; import com.rick.designpattern.facade.ConcreteFacade; import java.util.ArrayList; import java.util.List; /** * Created by MyPC on 2017/6/7. */ public class UnsharedConcreteFlyweight implements Flyweight { private List<Flyweight> flyweights; public UnsharedConcreteFlyweight() { this.flyweights = new ArrayList<Flyweight>(); } @Override public void operation(Object state) { for (Flyweight concreteFlyweight : flyweights) { concreteFlyweight.operation(state); } } public void add(Flyweight concreteFlyweight) { flyweights.add(concreteFlyweight); } }
