不正确
应该把他们转换成:
Calendar startTime = Calendar.getInstance();
        Calendar endTime = Calendar.getInstance();        startTime.add(Calendar.MONTH,-1);
        startTime.set(Calendar.DAY_OF_MONTH,startTime.getActualMinimum(Calendar.DATE));
        startTime.set(Calendar.HOUR_OF_DAY,0);
        startTime.set(Calendar.MINUTE,0);        endTime.add(Calendar.MONTH,-1);
        endTime.set(Calendar.DAY_OF_MONTH,endTime.getActualMaximum(Calendar.DATE));
        endTime.set(Calendar.HOUR_OF_DAY,23);
        endTime.set(Calendar.MINUTE,59);        long st = startTime.getTimeInMillis();
        long et = endTime.getTimeInMillis();
        long to = et - st;
        if((to/(60*60*24*1000))>30){
            //do something
        }
        System.out.println("(to/(60*60*24*1000))::::" + (to/(60*60*24*1000)));