设计模式之禅之设计模式-享元模式

 1 package com.yeepay.sxf.template23;
 2 /**
 3  * 【1】抽象享元角色一般为抽象类,在实际项目中,一般是一个实现类,它是描述一类事物的方法。
 4  * 在抽象角色中,一般需要把外部状态和内部状态(当然了,可以没有内部状态,只有行为也是可以的)定义出来
 5  * 避免子类的随意扩展
 6  * 【2】抽象享元中对外部状态加上了final关键字,防止意外产生,什么意外?
 7  * 获得了一个外部状态,然后无意修改了一下,池就混乱了
 8  * @author sxf
 9  *
10  */
11 public abstract class Flyweight {
12     //内部状态
13     private String intrinsic;
14     //外部状态
15     protected final String extrinsic;
16     //要求享元角色必须接受外部状态
17     public Flyweight(String extrinsic){
18         this.extrinsic=extrinsic;
19     }
20     
21     //定义业务操作
22     public abstract void operate();
23     //内部状态的getter/setter
24 
25     public String getExtrinsic() {
26         return extrinsic;
27     }
28     
29 }

 1 package com.yeepay.sxf.template23;
 2 
 3 import java.util.HashMap;
 4 
 5 /**
 6  * 享元工厂
 7  * @author sxf
 8  *
 9  */
10 public class FlyweightFactory {
11 
12     //定义一个池容器
13     private static HashMap<String, Flyweight> pool=new HashMap<String, Flyweight>();
14     //享元工厂
15     public static Flyweight getFlyweight(String extrinsic){
16         //需要返回的对象
17         Flyweight flyweight=null;
18         //在池中没有该对象
19         if(pool.containsKey(extrinsic)){
20             flyweight=pool.get(extrinsic);
21         }else{
22             //根据外部状态创建享元对象
23             flyweight=new ConcreteFlyweight1(extrinsic);
24             //放入池中
25             pool.put(extrinsic, flyweight);
26         }
27         return flyweight;
28     }
29 }

 1 package com.yeepay.sxf.template23;
 2 /**
 3  * 享元角色2
 4  * @author sxf
 5  *
 6  */
 7 public class ConcreteFlyweight2 extends Flyweight{
 8 
 9     //接收外部状态
10     public ConcreteFlyweight2(String extrinsic) {
11         super(extrinsic);
12     }
13 
14     //根据外部状态进行业务逻辑处理
15     @Override
16     public void operate() {
17         // TODO Auto-generated method stub
18         
19     }
20 
21 }

 1 package com.yeepay.sxf.template23;
 2 
 3 import java.util.HashMap;
 4 
 5 /**
 6  * 享元工厂
 7  * @author sxf
 8  *
 9  */
10 public class FlyweightFactory {
11 
12     //定义一个池容器
13     private static HashMap<String, Flyweight> pool=new HashMap<String, Flyweight>();
14     //享元工厂
15     public static Flyweight getFlyweight(String extrinsic){
16         //需要返回的对象
17         Flyweight flyweight=null;
18         //在池中没有该对象
19         if(pool.containsKey(extrinsic)){
20             flyweight=pool.get(extrinsic);
21         }else{
22             //根据外部状态创建享元对象
23             flyweight=new ConcreteFlyweight1(extrinsic);
24             //放入池中
25             pool.put(extrinsic, flyweight);
26         }
27         return flyweight;
28     }
29 }

 1 package com.yeepay.sxf.template23;
 2 /**
 3  * 客户端测试
 4  * @author sxf
 5  *
 6  */
 7 public class ClientTest {
 8 
 9     public static void main(String[] args) {
10         Flyweight flyweight=FlyweightFactory.getFlyweight("1234");
11         System.out.println("ClientTest.main()"+flyweight.toString());
12         Flyweight flyweight2=FlyweightFactory.getFlyweight("1234");
13         System.out.println("ClientTest.main()"+flyweight2.toString());
14         /**
15          * ClientTest.main()com.yeepay.sxf.template23.ConcreteFlyweight1@7150bd4d
16          * ClientTest.main()com.yeepay.sxf.template23.ConcreteFlyweight1@7150bd4d
17          */
18     }
19 }