实现代码如下：

public class Board extends JPanel{
 int width = Toolkit.getDefaultToolkit().getScreenSize().width;
 int height = Toolkit.getDefaultToolkit().getScreenSize().height;

 public HashMap points=new HashMap<>();//存放已出的所有其中，方便绘图和计算结果
 Board(){
  this.setVisible(true);
  drawBoard();
 }

 public int starX=300,starY=40,step=40,piecesR=28;
 BufferedImage buf;

 @Override
 public void paint(Graphics g){
  g.drawImage(buf, 0, 0,this);
 }

 void drawL(Point p,Graphics2D g1,int length,int bound){
  int x1=p.x-bound;
  int x2=p.x-bound-length;
  int x3=p.x+bound;
  int x4=p.x+bound+length;
  int y1=p.y-bound;
  int y2=p.y-bound-length;
  int y3=p.y+bound;
  int y4=p.y+bound+length;
  g1.drawLine(x1,y1,x2,y1);
  g1.drawLine(x1,y1,x1,y2);
  g1.drawLine(x1,y3,x2,y3);
  g1.drawLine(x1,y3,x1,y4);
  g1.drawLine(x3,y3,x3,y4);
  g1.drawLine(x3,y3,x4,y3);
  g1.drawLine(x3,y1,x4,y1);
  g1.drawLine(x3,y1,x3,y2);
 }

 public void drawBoard(){
  int Max=step*15;
  buf = new BufferedImage(this.width, this.height, BufferedImage.TYPE_INT_RGB);
  Graphics2D g1 = buf.createGraphics(); // 创建画笔

  g1.addRenderingHints((Map)(Toolkit.getDefaultToolkit().getDesktopProperty("awt.font.desktophints")));

  g1.setColor(new Color(46,139,87));//60,179,113//0,255,127
  g1.fillRect(0,0,this.width,this.height);

  g1.setColor(new Color(106,90,205));
  g1.fill3DRect(starX, starY, Max, Max, true);


  for (int i = 0; i <=15; i++) {
   g1.setColor(Color.WHITE);

   g1.drawLine(starX, starY+i*step, Max+starX, starY+i*step); //画棋盘横线
   g1.drawLine(starX+i*step, starY, starX+i*step, Max+starY); //画棋盘竖线

   g1.setColor(Color.black);
   g1.setFont(new Font("楷体",Font.BOLD,15));
   g1.drawString(numToCh(i),starX-((numToCh(i).length()==1)?25:35),starY+i*step+5);//纵行
   g1.drawString(numToCh(i),starX+i*step-((numToCh(i).length()==1)?5:15),starY-8);//横行

   g1.setColor(Color.BLACK);

   g1.setStroke(new BasicStroke(2.0f));

   if(i==4) {
    drawL(new Point(starX+i*step,starY+i*step),g1,8,4);
    drawL(new Point(starX+i*step,starY+12*step),g1,8,4);
   }
   if(i==12){
    drawL(new Point(starX+i*step,starY+i*step),g1,8,4);
    drawL(new Point(starX+i*step,starY+4*step),g1,8,4);
   }

  Iterator iterator=points.entrySet().iterator();
  while(iterator.hasNext()){
   Map.Entry entry=(Map.Entry)iterator.next();
   g1.setColor(entry.getValue());
   g1.fillOval(starX+(entry.getKey().x)*step-17,starY+(entry.getKey().y)*step-17,34,34);
  }

  String []str={"开始","悔棋","投降","帮助","重来"};
  for(int i=0;i