java 随机领取红包

private synchronized Double getRandomMoney(int remainSize, Double remainMoney) {
		// remainSize 剩余的红包数量
		// remainMoney 剩余的钱
		Double money = 0.0;
		if (remainSize == 1) {
			remainSize--;
			money = (double) Math.round(remainMoney * 100) / 100;
			System.out.println("=====> " + money);
			return money;
		}
		Random r = new Random();
		double min = 0.01; //
		double max = remainMoney / remainSize * 2;
		money = r.nextDouble() * max;
		money = money <= min ? 0.01 : money;
		money = Math.floor(money * 100) / 100;
		System.out.println("=====> " + money);
		remainSize--;
		remainMoney -= money;
		DecimalFormat df = new DecimalFormat("#.00");
		return Double.valueOf(df.format(money));
	}