/**

      * 获取当天时间零点

      * @return

      */

     public Date gettoday(){

         SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

         String day = sdf.format(new Date());

         Date today = null;

        try {

            today = sdf.parse(day);

        } catch (ParseException e) {

            e.printStackTrace();

        }

         return today;

     }

        /**

         * 时间转字符串（20181117）

         * @param time

         * @return

         */

        public String datetostring(Date time){

            //设置要获取到什么样的时间

            SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");

            //获取String类型的时间

            String createdate = sdf.format(time);

            return createdate;

        }

        /**

         * 日期增加天数

         * @param date

         * @param num

         * @return

         */

         public Date addDay(Date date, int num) {

             Calendar startDT = Calendar.getInstance();

             startDT.setTime(date);

             startDT.add(Calendar.DAY_OF_MONTH, num);

             return startDT.getTime();

            }

         /**

          * 两日期相差天数

          * @param date1

          * @param date2

          * @return

          */

         public int getday(Date date1,Date date2){

                 Calendar cal1 = Calendar.getInstance();

                cal1.setTime(date1);

                Calendar cal2 = Calendar.getInstance();

                cal2.setTime(date2);

                int day1= cal1.get(Calendar.DAY_OF_YEAR);

                int day2 = cal2.get(Calendar.DAY_OF_YEAR);

                return day2-day1;

         }