【GOF23设计模式】享元模式

来源：http://www.bjsxt.com/ 
一、【GOF23设计模式】_享元模式、享元池、内部状态、外部状态、线程池、连接池

 package com.test.flyweight;
 /**
  * FlyWeight抽象享元类
  */
 public interface ChessFlyWeight {
     void setColor(String c);
     String getColor();
     void display(Coordinate c);
 }

 /**
  * ConcreteFlyWeight具体享元类
  */
 class ConcreteChess implements ChessFlyWeight {
     private String color;

     public ConcreteChess(String color) {
         super();
         this.color = color;
     }

     @Override
     public void setColor(String c) {
         this.color = c;
     }

     @Override
     public String getColor() {
         return color;
     }

     @Override
     public void display(Coordinate c) {
         System.out.println("棋子颜色："+color);
         System.out.println("棋子位置："+c.getX()+"------"+c.getY());
     }
 }

 package com.test.flyweight;
 /**
  * 外部状态UnSharedConcreteFlyWeight非共享享元类
  */
 public class Coordinate {
     private int x,y;

     public Coordinate(int x, int y) {
         super();
         this.x = x;
         this.y = y;
     }

     public int getX() {
         return x;
     }

     public void setX(int x) {
         this.x = x;
     }

     public int getY() {
         return y;
     }

     public void setY(int y) {
         this.y = y;
     }
 }

package com.test.flyweight;

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

/**
 * 享元工厂类
 */
public class ChessFlyWeightFactory {
    //享元池
    private static Map<String, ChessFlyWeight> map = new HashMap<String, ChessFlyWeight>();

    public static ChessFlyWeight getChess(String color) {
        if(map.get(color)!=null){
            return map.get(color);
        }else{
            ChessFlyWeight cfw = new ConcreteChess(color);
            map.put(color, cfw);
            return cfw;
        }
    }
}

 package com.test.flyweight;

 public class Client {
     public static void main(String[] args) {
         ChessFlyWeight chess1 = ChessFlyWeightFactory.getChess("黑色");
         ChessFlyWeight chess2 = ChessFlyWeightFactory.getChess("黑色");
         System.out.println(chess1);
         System.out.println(chess2);

         System.out.println("增加外部状态的处理============");
         chess1.display(new Coordinate(10,10));
         chess2.display(new Coordinate(20,20));
     }
 }

控制台输出：
com.test.flyweight.ConcreteChess@1db9742
com.test.flyweight.ConcreteChess@1db9742
增加外部状态的处理============
棋子颜色：黑色
棋子位置：10------10
棋子颜色：黑色
棋子位置：20------20