java设计模式 GOF23 11 享元模式

package com.lz.flyWeight;

/*
 * 享元模式
 * 内部状态
 * 模拟棋盘,因为一盘棋其中棋子的颜色都一样
 * 只有位置不一样，所以可以将颜色共享，这样可以节省内存空间
 * 棋盘接口
 */

interface Chess {
    void setColor(String c);
    String getColor();
    void display(ChessLoc chess);
}

class ChessFlyWeight implements Chess {
    private String c;
    
    @Override
    public void setColor(String c) {
        this.c = c;
    }

    @Override
    public String getColor() {
        return this.c;
    }

    public ChessFlyWeight(String c) {
        super();
        this.c = c;
    }

    @Override
    public void display(ChessLoc chess) {
        System.out.print("颜色:"+c+"  ");
        System.out.print("坐标("+chess.getX());
        System.out.println(","+chess.getY()+")");
    }
}

package com.lz.flyWeight;

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

/*
 * 享元工厂类
 */
public class FlyWeightFactory {
    /*
     * 享元池对象
     */
    private static Map<String, Chess> map = new HashMap<String, Chess>();
    
    public static Chess getChess(String c) {
        if ( map.get(c) != null) {
            return map.get(c);
        } else {
            ChessFlyWeight chess = new ChessFlyWeight(c);
            map.put(c, chess);
            return chess;
        }
    }
}

package com.lz.flyWeight;

/*
 * 测试类
 */
public class Client {
    public static void main(String[] args) {
        Chess tmp1 = FlyWeightFactory.getChess("黑");
        Chess tmp2 = FlyWeightFactory.getChess("红色");
        System.out.println(tmp1);
        System.out.println(tmp2);
        tmp1.display(new ChessLoc(1, 2));
        tmp2.display(new ChessLoc(5, 4));
    }
}

package com.lz.flyWeight;

/**
 * 位置信息
 * 外部状态，不可共享
 */
public class ChessLoc {
    private int x;
    private int y;
    public ChessLoc(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;
    }
}