Java 8 之前日期时间写法
/**
* 获取当前时间小时整点时间
*
* @param
* @return
*/
public static Date getCurrentHourTime() {
return getHourTime(new Date(), 0, "=");
}

/**
 * 获取指定时间上n个小时整点时间
 *
 * @param date
 * @return
 */
public static Date getLastHourTime(Date date, int n) {
    return getHourTime(date, n, "-");
}

/**
 * 获取指定时间下n个小时整点时间
 *
 * @param date
 * @return
 */
public static Date getNextHourTime(Date date, int n) {
    return getHourTime(date, n, "+");
}

/**
 * 获取指定时间n个小时整点时间
 *
 * @param date
 * @return
 */
public static Date getHourTime(Date date, int n, String direction) {
    Calendar ca = Calendar.getInstance();
    ca.setTime(date);
    ca.set(Calendar.MINUTE, 0);
    ca.set(Calendar.SECOND, 0);
    switch (direction) {
        case "+":
            ca.set(Calendar.HOUR_OF_DAY, ca.get(Calendar.HOUR_OF_DAY) + n);
            break;
        case "-":
            ca.set(Calendar.HOUR_OF_DAY, ca.get(Calendar.HOUR_OF_DAY) - n);
            break;
        case "=":
            ca.set(Calendar.HOUR_OF_DAY, ca.get(Calendar.HOUR_OF_DAY));
            break;
        default:
            ca.set(Calendar.HOUR_OF_DAY, ca.get(Calendar.HOUR_OF_DAY));
    }

    date = ca.getTime();
    return date;
}

Java 8 新的日期时间类 写法

/**
 * 获取当前时间上iHour个小时整点时间
 *
 * @param iHour 小时数
 * @return
 */
public static Date getLastHourTime(Integer iHour) {
    LocalDateTime localDateTime = LocalDateTime.now().minusHours(iHour).toLocalDate().atTime(LocalDateTime.now().minusHours(iHour).getHour(), 0, 0);
    return Date.from(localDateTime.atZone(ZoneId.systemDefault()).toInstant());
}

/**
 * 获取当前时间的整点时间向前推iSecond秒
 *
 * @param iSecond 秒数
 * @return
 */
public static Date getLastSecondByCurrHourTime(Integer iSecond) {
    LocalDateTime localDateTime = LocalDateTime.now().toLocalDate().atTime(LocalDateTime.now().getHour(), 0, 0).minusSeconds(iSecond);
    return Date.from(localDateTime.atZone(ZoneId.systemDefault()).toInstant());
}