有关取日期的方法

1.返回距今多少（past）天的日期

public static String getPastDate(int past) {
    Calendar calendar = Calendar.getInstance();
    calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) - past);
    Date today = calendar.getTime();
    SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
    String result = format.format(today);
    return result;
}

此方法返回距今多少（past）天的日期（字符串表示）。

Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.MONTH, -1);//表示取上一个的月份信息

2.返回本月剩余天数

Date nowDate = new Date();
SimpleDateFormat sdfDay = new SimpleDateFormat("yyyy-MM-dd");
String curDay = sdfDay.format(nowDate);
String lastday = "";
Calendar cale = Calendar.getInstance();
cale.add(Calendar.MONTH, 1);
cale.set(Calendar.DAY_OF_MONTH, 0);
lastday = sdfDay.format(cale.getTime());
Integer remainDays = 0;
try {
   remainDays = daysBetween(curDay,lastday);//本月剩余天数
} catch (ParseException e) {
   e.printStackTrace();
}

//返回两个日期（字符串表示）之间的天数

public static int daysBetween(String smdate,String bdate) throws ParseException{
   SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
   Calendar cal = Calendar.getInstance();
   cal.setTime(sdf.parse(smdate));
   long time1 = cal.getTimeInMillis();
   cal.setTime(sdf.parse(bdate));
   long time2 = cal.getTimeInMillis();
   long between_days=(time2-time1)/(1000*3600*24);

   return Integer.parseInt(String.valueOf(between_days));
}

 3.返回当月天数

Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.MONTH, -1);
calendar.set(Calendar.DATE, 1);//把日期设置为当月第一天
calendar.roll(Calendar.DATE, -1);//日期回滚一天，也就是最后一天
int curMonthDayNum = calendar.get(Calendar.DATE);//当月天数

 4.返回下一月天数

Calendar nextmonthCal = Calendar.getInstance();
nextmonthCal.set(Calendar.MONTH, nextmonthCal.get(Calendar.MONTH) + 1);
Date nextDate =  nextmonthCal.getTime();
String nextMonth = sdfMonth.format(nextDate);

Calendar calendar = Calendar.getInstance();
calendar.setTime(nextDate);
int nextMonthDayNum = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);//下月天数