根据月份获得当月天数

public static void main(String args[]) {
		String monthStr = "2";
		int month = Integer.parseInt(monthStr);
		Calendar cal = Calendar.getInstance();
		cal.set(Calendar.MONTH, month-1);
		cal.set(Calendar.DAY_OF_MONTH, 1);
		cal.set(Calendar.HOUR, 0);
		DecimalFormat format = new DecimalFormat();
		format.setMinimumIntegerDigits(2);
		format.setMaximumFractionDigits(0);
		format.setGroupingUsed(false);
//		System.out.println(cal.get(Calendar.MONTH));
		while (cal.get(Calendar.MONTH) == (month - 1)) {
			int day = cal.get(Calendar.DAY_OF_MONTH);
			cal.add(Calendar.DATE, 1);
			System.out.println(format.format(day));
		}
	}