设计模式之享元模式详解（下）

news2024/11/24 7:02:51

4）完整解决方案-不带外部状态

1.结构图

在这里插入图片描述

IgoChessman充当抽象享元类，BlackIgoChessman和WhiteIgoChessman充当具体享元类，IgoChessmanFactory充当享元工厂类。

2.代码案例

抽象享元类

//围棋棋子类：抽象享元类
abstract class IgoChessman {
    public abstract String getColor();

    public void display() {
        System.out.println("棋子颜色：" + this.getColor());
    }
}

具体享元类

//黑色棋子类：具体享元类
public class BlackIgoChessman extends IgoChessman {
    public String getColor() {
        return "黑色";
    }
}

//白色棋子类：具体享元类
public class WhiteIgoChessman extends IgoChessman {
    public String getColor() {
        return "白色";
    }
}

享元工厂类

import java.util.Hashtable;

//围棋棋子工厂类：享元工厂类，使用单例模式进行设计
public class IgoChessmanFactory {
    private static IgoChessmanFactory instance = new IgoChessmanFactory();
    private static Hashtable ht; //使用Hashtable来存储享元对象，充当享元池

    private IgoChessmanFactory() {
        ht = new Hashtable();
        IgoChessman black, white;
        black = new BlackIgoChessman();
        ht.put("b", black);
        white = new WhiteIgoChessman();
        ht.put("w", white);
    }

    //返回享元工厂类的唯一实例
    public static IgoChessmanFactory getInstance() {
        return instance;
    }

    //通过key来获取存储在Hashtable中的享元对象
    public static IgoChessman getIgoChessman(String color) {
        return (IgoChessman) ht.get(color);
    }
}

客户端类

public class Client {
    public static void main(String[] args) {
        IgoChessman black1, black2, black3, white1, white2;
        IgoChessmanFactory factory;

        //获取享元工厂对象
        factory = IgoChessmanFactory.getInstance();

        //通过享元工厂获取三颗黑子
        black1 = factory.getIgoChessman("b");
        black2 = factory.getIgoChessman("b");
        black3 = factory.getIgoChessman("b");
        System.out.println("判断两颗黑子是否相同：" + (black1 == black2));

        //通过享元工厂获取两颗白子
        white1 = factory.getIgoChessman("w");
        white2 = factory.getIgoChessman("w");
        System.out.println("判断两颗白子是否相同：" + (white1 == white2));

        //显示棋子
        black1.display();
        black2.display();
        black3.display();
        white1.display();
        white2.display();
    }
}

5）完整解决方案-带外部状态

1.结构图

在这里插入图片描述

增加了一个坐标类Coordinates，同时抽象享元类IgoChessman中的display()方法也对应增加一个Coordinates类型的参数，用于在显示棋子时指定其坐标。

2.代码案例

//坐标类：外部状态类
@AllArgsConstructor
@Data
public class Coordinates {
    private int x;
    private int y;
}
 
//围棋棋子类：抽象享元类
abstract class IgoChessman {
	public abstract String getColor();
	
	public void display(Coordinates coord){
		System.out.println("棋子颜色：" + this.getColor() + "，棋子位置：" + coord.getX() + "，" + coord.getY() );	
	}
}

//客户端类
public class Client {
    public static void main(String[] args) {
        IgoChessman black1,black2,black3,white1,white2;
        IgoChessmanFactory factory;

        //获取享元工厂对象
        factory = IgoChessmanFactory.getInstance();

        //通过享元工厂获取三颗黑子
        black1 = factory.getIgoChessman("b");
        black2 = factory.getIgoChessman("b");
        black3 = factory.getIgoChessman("b");
        System.out.println("判断两颗黑子是否相同：" + (black1==black2));

        //通过享元工厂获取两颗白子
        white1 = factory.getIgoChessman("w");
        white2 = factory.getIgoChessman("w");
        System.out.println("判断两颗白子是否相同：" + (white1==white2));

        //显示棋子，同时设置棋子的坐标位置
        black1.display(new Coordinates(1,2));
        black2.display(new Coordinates(3,4));
        black3.display(new Coordinates(1,3));
        white1.display(new Coordinates(2,5));
        white2.display(new Coordinates(2,4));
    }
}