享元模式--Java实现

画类图

在围棋中，黑棋和白棋对象均只有一个，但是它们可以在不同的位置进行共享；

具体代码实现

//Chess.java
package org.example.design010;

public abstract class Chess {
    public abstract String getColor();
    public void locate(Coordinates co){
        System.out.println(this.getColor()+"棋的位置是：("+co.getX()+","+co.getY()+")");
    }
}

//WhiteChess.java
package org.example.design010;

public class WhiteChess extends Chess{
    @Override
    public String getColor() {
        return "白";
    }
}

//BlackChess.java
package org.example.design010;

public class BlackChess extends Chess{
    @Override
    public String getColor() {
        return "黑";
    }
}

//Coordinates.java
package org.example.design010;

public class Coordinates {
    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;
    }

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

    private int x;
    private int y;
}

//ChessFactory.java
package org.example.design010;

import java.util.Hashtable;

public class ChessFactory {
    public static ChessFactory getChessFactory() {
        return chessFactory;
    }

    private static Hashtable hashTable;
    public ChessFactory(){
        hashTable=new Hashtable();
        Chess black,white;
        black=new BlackChess();
        hashTable.put("b", black);
        white=new WhiteChess();
        hashTable.put("w",white);
    }

    public static ChessFactory getInstance() {
        return chessFactory;
    }

    private static ChessFactory chessFactory=new ChessFactory();

    public static Chess getChess(String color){
        return (Chess) hashTable.get(color);
    }

}

//Client.java
package org.example.design010;

public class Client {
    public static void main(String[] args) {
        Chess black1,black2,black3,white1,white2;
        ChessFactory factory;
        factory=ChessFactory.getInstance();

        black1=ChessFactory.getChess("b");
        black2=ChessFactory.getChess("b");
        black3=ChessFactory.getChess("b");
        white1=ChessFactory.getChess("w");
        white2=ChessFactory.getChess("w");

        black1.locate(new Coordinates(1,2));
        black2.locate(new Coordinates(2,3));
        black3.locate(new Coordinates(3,4));
        white1.locate(new Coordinates(4,5));
        white2.locate(new Coordinates(5,6));

    }
}