常用工具类（1）—DateUtil实现日期格式化和解析

引入依赖：

<dependency>
    <groupId>joda-time</groupId>
    <artifactId>joda-time</artifactId>
    <version>2.10.14</version>
</dependency>

工具类代码：一些常见时间的查询方法

public class DateUtil {
    public static final DateTimeFormatter DATE_FORMAT = DateTimeFormat.forPattern("yyyy-MM-dd");
    public static final DateTimeFormatter DATE_INT_FORMAT = DateTimeFormat.forPattern("yyyyMMdd");
    public static final DateTimeFormatter DATE_TIME_FORMAT = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss");
    public static final DateTimeFormatter INT_MONTH_FORMATTER = DateTimeFormat.forPattern("yyyyMM");


    /**
     * 解析表达式为时间戳
     */
    public static long parseDate(String date) {
        if (StringUtils.isEmpty(date)) {
            return 0;
        }
        return DateTime.parse(date, DATE_FORMAT).toDate().getTime();
    }


    /**
     * 指定日期当天开始的时间戳, 单位:ms
     */
    public static long getDayBeginMs(long timestamp) {
        DateTime date = new DateTime(timestamp);
        return date.withMillisOfDay(0).getMillis();
    }

    /**
     * 今天结束的时间戳, 单位:ms
     */
    public static long getTodayEndMs() {
        DateTime date = new DateTime();
        long nextDayBeginSt = date.withMillisOfDay(0).plusDays(1).getMillis();
        return nextDayBeginSt - 1;
    }

    /**
     * 当前年开始的时间戳，单位:ms
     */
    public static long getYearBeginMs() {
        DateTime date = new DateTime();
        return date.monthOfYear().withMinimumValue()
                .dayOfMonth().withMinimumValue()
                .withMillisOfDay(0).getMillis();
    }

    /**
     * 当前年结束的时间戳，单位:ms
     */
    public static long getYearEndMs() {
        DateTime date = new DateTime();
        return date.plusDays(1).dayOfMonth().withMinimumValue()
                .dayOfMonth().withMinimumValue()
                .withMillisOfDay(0).getMillis();
    }

    /**
     * 前days天开始的时间戳，单位:ms
     */
    public static long getDaysBeforeBeginMs(int days) {
        DateTime date = new DateTime();
        return date.withMillisOfDay(0).plusDays(days).getMillis();
    }

    /**
     * 前days天结束的时间戳，单位:ms
     */
    public static long getDaysBeforeEndMs(int days) {
        DateTime date = new DateTime();
        return date.minusDays(days).minusDays(1).getMillis() - 1;
    }

    /**
     * 当前月开始的时间戳，单位:ms
     */
    public static long getMonthBeginMs() {
        DateTime date = new DateTime();
        return date.dayOfMonth().withMinimumValue()
                .withMillisOfDay(0).getMillis();
    }

    /**
     * 当前月结束的事件戳，单位：ms
     */
    public static long getMonthEndMs() {
        DateTime date = new DateTime();
        return date.plusMonths(1).dayOfMonth().withMinimumValue()
                .withMillisOfDay(0).getMillis();
    }

    /**
     * 指定月份的最后一天
     *
     * @param month 202201
     * @return 20220131
     */
    public static int getMonthLastDay(int month) {
        DateTime date = DateTime.parse(String.valueOf(month), INT_MONTH_FORMATTER);
        return Integer.parseInt(DATE_INT_FORMAT.print(date.dayOfMonth().withMaximumValue().getMillis()));
    }

    /**
     * 获取前n天的格式化的时间格式：yyyy-MM-dd
     */
    public static String getDayFormatBefore(int days) {
        DateTime date = new DateTime();
        return DATE_FORMAT.print(date.withMillisOfDay(0).minusDays(days).getMillis());
    }

}