Android Calendar日历获取几个月的总天数，每月的月初时间和月末时间

    /**
     * 获取当月剩余天数（含当天）+往后几个月的天数总和
     * @param monthNum 往后几个月
     * @return 总天数
     */
    public static int getDaysWithMonthYear(int monthNum){
        int days = 0;
        Calendar calendar = Calendar.getInstance();
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH);
        //当天日期
        int day = calendar.get(Calendar.DAY_OF_MONTH);
        //月份的最小日期
        int minDay = calendar.getActualMinimum(Calendar.DAY_OF_MONTH);
        //月份的最大日期
        int maxDay = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
        days +=maxDay - day + 1;
        for (int i = 0; i < monthNum; i++) {
            //设置日历为下一个月，获取天数
            calendar.add(Calendar.MONTH,1);
            int nextYear = calendar.get(Calendar.YEAR);
            int nextMonth = calendar.get(Calendar.MONTH);
            int nextMaxDay = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
            days +=nextMaxDay;

        }
        return days;
    }

    /**
     * 获取月初时间
     * @param date
     * @return
     */
    public static Date getStartDayOfMonth(Date date){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.DAY_OF_MONTH,1);
        return calendar.getTime();
    }
    /**
     * 获取月末时间
     * @param date
     * @return
     */
    public static Date getEndDayOfMonth(Date date){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.DAY_OF_MONTH,calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
        return calendar.getTime();
    }