设计模式12-享元模式

1. 概念

      享元模式（FlyWeight），运用共享技术有效的支持大量细粒度的对象 

2. 案例 

 

/**********************************************************************

 * <pre>

 * FILE : Demo01.java

 * CLASS : Demo01

 *

 * AUTHOR : Liaokailin

 *

 * FUNCTION : TODO

 *

 *

 *======================================================================

 * CHANGE HISTORY LOG

 *----------------------------------------------------------------------

 * MOD. NO.|   DATE   |   NAME  | REASON  | CHANGE REQ.

 *----------------------------------------------------------------------

 *             |2014-3-7|Liaokailin| Created |

 * DESCRIPTION:

 * </pre>

 ***********************************************************************/

package org.demo.fylweight.demo01;



import java.util.HashMap;

import java.util.Map;





interface Flyweight{

    void action(int arg) ;

}





class FlyweightImpl implements Flyweight{

    @Override

    public void action(int arg) {

        System.out.println("the value of param : " + arg);

    }

}



@SuppressWarnings("unchecked")

class FlyweightFactory{

    @SuppressWarnings("rawtypes")

    private static Map flyweights = new HashMap() ;

    public FlyweightFactory(String arg){

        flyweights.put(arg, new FlyweightImpl()) ;

    }

    

    public static Flyweight getFlyweight(String key){

        if(flyweights.get(key)==null){

            flyweights.put(key, new FlyweightImpl()) ;

        }

        return (Flyweight) flyweights.get(key) ;

    }

    

    public static int getSize(){

        return flyweights.size() ;

    }

}





public class Demo01 {

       public static void main(String args[]){

           Flyweight fly1 = FlyweightFactory.getFlyweight("a");

           System.out.println(fly1);

           fly1.action(1) ;

           Flyweight fly2 = FlyweightFactory.getFlyweight("a");

           System.out.println(fly1 == fly2);

           

           Flyweight fly3 = FlyweightFactory.getFlyweight("b"); 

           fly3.action(2); 

           Flyweight fly4 = FlyweightFactory.getFlyweight("c"); 

           fly4.action(3); 

           Flyweight fly5 = FlyweightFactory.getFlyweight("d");

           fly5.action(4); 

           System.out.println(FlyweightFactory.getSize());

           

           

       }

}

 

结果：

　

org.demo.fylweight.demo01.FlyweightImpl@530cf2

the value of param : 1

true

the value of param : 2

the value of param : 3

the value of param : 4

4