java時間工具類

時間工具類

public class DateUtils {

    /**
     * 擷取目前時間("yyyy-MM-dd")
     * @return yyyy-MM-dd
     */
    public static String getTime(){
        Date date = new Date();
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        String time = simpleDateFormat.format(date);
        return time;
    }

    /**
     * 比較兩個時間（string:"yyyy-MM-dd"）大小
     * @param date1
     * @param date2
     * @return 傳回大于0:date1>date2;傳回0:date1=date2;傳回小于0:date1<date2
     * @throws ParseException
     */
    public static int compareTime(String date1,String date2) throws ParseException {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        Date time1 = simpleDateFormat.parse(date1);
        Date time2 = simpleDateFormat.parse(date2);
        return date1.compareTo(date2);
    }

    /**
     * 擷取指定月份最後一天日期（傳回值："yyyy-MM-dd"）
     * 參數："yyyy-MM"
     */
    public static String getLastDate(String date) {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.YEAR, Integer.parseInt(date.substring(0,4)));
        calendar.set(Calendar.MONTH, Integer.parseInt(date.substring(5))-1);
        calendar.set(Calendar.DAY_OF_MONTH,1);
        calendar.roll(Calendar.DAY_OF_MONTH,-1);
        String lastDate = simpleDateFormat.format(calendar.getTime());
        return lastDate;
    }

    /**
     * 擷取兩個日期相差天數
     * @param date1"yyyy-MM-dd"
     * @param date2"yyyy-MM-dd"
     * @return String
     */
    public static String diffDate(String date1,String date2) throws ParseException {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        long time1 = format.parse(date1).getTime();
        long time2 = format.parse(date2).getTime();
        long diffDate = (time2-time1)/1000/60/60/24;
        return String.valueOf(Math.abs(diffDate));
    }

    /**
     * 擷取時間相關資料
     * @param date"yyyy-MM-dd"
     * @param i
     * @return String
     */
    public static String getDateData(String date,int i){
        String s;
        LocalDate localDate = LocalDate.of(Integer.parseInt(date.substring(0,4)),Integer.parseInt(date.substring(5,7)),Integer.parseInt(date.substring(8)));
        switch (i){
            case 1:
                s = String.valueOf(localDate.getYear()); //這一年
                break;
            case 2:
                s = String.valueOf(localDate.getMonth()); //這個月
                break;
            case 3:
                s = String.valueOf(localDate.getDayOfMonth()); //這個月的第幾天
                break;
            case 4:
                s = String.valueOf(localDate.getDayOfWeek()); //這個周的第幾天
                break;
            case 5:
                s = String.valueOf(localDate.lengthOfMonth()); //這個月多少天
                break;
            case 6:
                s = String.valueOf(localDate.isLeapYear()); //是否是閏年
                break;
            default:
                System.out.println("暫無你要的方法");
            return null;
        }
        return s;
    }
}