计算月的天数

public class Common {
	private static SimpleDateFormat format = new SimpleDateFormat("yyyy-MM");

	/**
	 * @param dateString example:2011-6
	 * @return
	 */
	public static int getDayCountOfMonth(String dateString) {
		try {
			Date date = format.parse(dateString);
			Calendar calendar = new GregorianCalendar();
			calendar.setTime(date);
			return calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return -1;
	}
}