Date

Calendar start = Calendar.getInstance();start.set( Calendar.HOUR_OF_DAY,00);start.set( Calendar.MINUTE, 0);start.set( Calendar.SECOND,0);Calendar end = Calendar.getInstance();end.set(Calendar.HOUR_OF_DAY,23);end.set( Calendar.MINUTE,59);end.set(Calendar.SECOND,59);SimpleDateFormat sm = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");System.out.println("start:" + sm.format(start.getTime()));System.out.println("end:" + sm.format(end.getTime()));

LocalDateTime

public static void main(String[] args) {        Date date = new Date();        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");        System.out.println("以后工夫：" + sdf.format(date));        System.out.println("==============================");        System.out.println("明天开始工夫：" + sdf.format(getStartOfDay(date)));        System.out.println("明天完结工夫：" + sdf.format(getEndOfDay(date)));    }    /**     *      * @description: 取得当天最小工夫     * @author: Jeff     * @date: 2019年12月21日     * @param date     * @return     */    public static Date getStartOfDay(Date date) {        LocalDateTime localDateTime = LocalDateTime.ofInstant(Instant.ofEpochMilli(date.getTime()),                ZoneId.systemDefault());        LocalDateTime startOfDay = localDateTime.with(LocalTime.MIN);        return Date.from(startOfDay.atZone(ZoneId.systemDefault()).toInstant());    }    /**     *      * @description: 取得当天最大工夫     * @author: Jeff     * @date: 2019年12月21日     * @param date     * @return     */    public static Date getEndOfDay(Date date) {        LocalDateTime localDateTime = LocalDateTime.ofInstant(Instant.ofEpochMilli(date.getTime()),                ZoneId.systemDefault());        LocalDateTime endOfDay = localDateTime.with(LocalTime.MAX);        return Date.from(endOfDay.atZone(ZoneId.systemDefault()).toInstant());    }

起源

LocalDateTime
Date