java时间类型转换方法

java时间类型转换方法

1. Calendar 转 LocalDateTime

    /**
     * Calendar 转 LocalDateTime
     * @param calendar
     * @return
     */
    public static LocalDateTime calenderToLocalDateTime(Calendar calendar){
        if (calendar == null) {
            return null;
        }
        return LocalDateTime.ofInstant(calendar.toInstant(), ZoneOffset.systemDefault());
    }


    /**
     * 将Calendar转成LocalDateTime
     * 第二种方法
     */
    public static LocalDateTime getLocalDateTime(Calendar calendar) {
        return LocalDateTime.of(
                ToolForDateTime.getYearByCalendar(calendar)
                , ToolForDateTime.getMonthByCalendar(calendar)
                , ToolForDateTime.getDayByCalendar(calendar)
                , ToolForDateTime.getHourByCalendar(calendar)
                , ToolForDateTime.getMinuteByCalendar(calendar)
                , ToolForDateTime.getSecondByCalendar(calendar)
                , 0
        );
    }

2. LocalDateTime转成Calendar

    /**
     * 将LocalDateTime转成Calendar
     */
    public static Calendar getCalendarByLocalDateTime(LocalDateTime localDateTime) {
        int year = localDateTime.getYear();
        int month = localDateTime.getMonthValue() - 1;
        int day = localDateTime.getDayOfMonth();
        int hour = localDateTime.getHour();
        int minute = localDateTime.getMinute();
        int second = localDateTime.getSecond();
        int millis = localDateTime.get(ChronoField.MILLI_OF_SECOND);
        Calendar calendar = new Calendar.Builder() {{
            setDate(year, month, day);
            setTimeOfDay(hour, minute, second, millis);
        }}.build();
        return calendar;
    }

3. date 转 LocalDateTime

    /**
     * date 转 LocalDateTime
     * @param date
     * @return
     */
    public static LocalDateTime dateToLocalDateTime(Date date) {
        if( date == null ){
            return null;
        }
        return date.toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();
    }


    /**
     * date 转 LocalDateTime
     * 方式二
     * @param date
     * @return
     */
    public static LocalDateTime dateToLocalDateTime(Date date) {
        Instant instant = date.toInstant();
        ZoneId zoneId = ZoneId.systemDefault();
        return LocalDateTime.ofInstant(instant, zoneId);
    }

4. LocalDate转Date

    /**
     * LocalDate转Date
     * @param localDate
     * @return
     */
    public static Date localDate2Date(LocalDate localDate) {
        if (null == localDate) {
            return null;
        }
        ZonedDateTime zonedDateTime = localDate.atStartOfDay(ZoneId.systemDefault());
        return Date.from(zonedDateTime.toInstant());
    }

5. LocalDateTime 转换为string

    /**
     * 常用的时间格式
     */
    public static final String format_DateTime = "yyyy-MM-dd HH:mm:ss";
    public static final String format_Date = "yyyy-MM-dd";

    /**
     * LocalDateTime 转换为string
     * yyyy-MM-dd HH:mm:ss SSS
     */
    public static String LocalDateTimeToString(LocalDateTime localDateTime){
        DateTimeFormatter df = DateTimeFormatter.ofPattern(format_DateTime);
        String result = df.format(localDateTime);
        return result;
    }

    /**
     * LocalDateTime 转换为string
     * yyyy-MM-dd
     */
    public static String LocalDateTimeToStringToDate(LocalDateTime localDateTime){
        DateTimeFormatter df = DateTimeFormatter.ofPattern(format_Date);
        String result = df.format(localDateTime);
        return result;
    }

6. string 转换为LocalDateTime

    /**
     * 常用的时间格式
     */
    public static final String format_DateTime = "yyyy-MM-dd HH:mm:ss";

    /**
     * string 转换为LocalDateTime
     */
    public static LocalDateTime stringToLocalTime(String str){
        DateTimeFormatter df = DateTimeFormatter.ofPattern(format_DateTime);
        LocalDateTime dateTime = LocalDateTime.parse(str, df);
        return dateTime;
    }

7. date转string

    // date转string
    public static String dateToString(Date date){
        SimpleDateFormat ft = new SimpleDateFormat("yyyy-MM-dd");
        return ft.format(date);
    }

8. string转date（只转换年月日，转换后时分秒默认：00:00:00）

    /**
     * string转date
     * 只转换年月日
     * @param str
     * @return
     * @throws ParseException
     */
    public static Date stringToDate(String str) throws ParseException {
        SimpleDateFormat ft = new SimpleDateFormat("yyyy-MM-dd");
        return ft.parse(str);
    }

9. string转date（年月日时分秒）

    /**
     * 常用的时间格式
     */
    public static final String format_DateTime = "yyyy-MM-dd HH:mm:ss";

    /**
     * string转date
     * 转换 年月日时分秒
     * @param str
     * @return
     * @throws ParseException
     */
    public static Date stringToTdate(String str) throws ParseException {
        return new SimpleDateFormat(format_DateTime).parse(str);
    }

10. yyyy-MM-dd格式的字符串转化为 x年x月x日

    /**
     * yyyy-MM-dd转化为 x年x月x日
     */
    public static String StringDateToYearMonthDay(String s){
        String[] split = s.split("-");
        return split[0] + "年" + split[1] + "月" + split[2] + "日";
    }