code: private Color getRandColor(int fc, int bc) {
  		Random random = new Random();
  		if (fc > 255)
  			fc = 255;
  		if (bc > 255)
  			bc = 255;
  		int r = fc + random.nextInt(bc - fc);
  		int g = fc + random.nextInt(bc - fc);
  		int b = fc + random.nextInt(bc - fc);
  		return new Color(r, g, b);
  	}
docs: /*
  给定范围获得随机颜色