得到几个月之内的天数（大家看看有没有更好的方法）

/**   * 得到指定月的天数   * */  public static int getMonthLastDay(int year, int month)   {       Calendar a = Calendar.getInstance();       a.set(Calendar.YEAR, year);       a.set(Calendar.MONTH, month - 1);       a.set(Calendar.DATE, 1);//把日期设置为当月第一天       a.roll(Calendar.DATE, -1);//日期回滚一天，也就是最后一天       int maxDate = a.get(Calendar.DATE);       return maxDate;   }  public static int getSameMonthDay(int year, int startYear, int month, int startMonth, int i){int threeMonthDay = 0;if(startMonth<i){if(month==0){month += 12;year=year-1;}if(month>0&&(year==startYear)){threeMonthDay += getSameMonthDay(year, startYear, month-1, startMonth, i);}else if(12-i+startMonth<=month){threeMonthDay += getSameMonthDay(year, startYear, month-1, startMonth, i);}}else{if(startMonth-i<=month){threeMonthDay += getSameMonthDay(year, startYear, month-1, startMonth, i);}}threeMonthDay += getMonthLastDay(year, month);return threeMonthDay;}