项目结束,大量使用到日期记录 分享一下日期工具类

public class DateUtil {

    /**
     * 锁对象
     */
    private static final Object lockObj = new Object();

    /**
     * 存放不同的日期模板格式的sdf的Map
     */
    private static Map<String, ThreadLocal<SimpleDateFormat>> sdfMap = new HashMap<>();


    /**
     * 返回一个ThreadLocal的sdf,每个线程只会new一次sdf
     */
    private static SimpleDateFormat getSdf(final String pattern) {
        ThreadLocal<SimpleDateFormat> tl = sdfMap.get(pattern);

        // 此处的双重判断和同步是为了防止sdfMap这个单例被多次put重复的sdf
        if (tl == null) {
            synchronized (lockObj) {
                tl = sdfMap.get(pattern);
                if (tl == null) {
                    // 只有Map中还没有这个pattern的sdf才会生成新的sdf并放入map
                    System.out.println("put new sdf of pattern " + pattern + " to map");

                    // 这里是关键,使用ThreadLocal<SimpleDateFormat>替代原来直接new SimpleDateFormat
                    tl = ThreadLocal.withInitial(() -> {
                        System.out.println("thread: " + Thread.currentThread() + " init pattern: " + pattern);
                        return new SimpleDateFormat(pattern);
                    });
                    sdfMap.put(pattern, tl);
                }
            }
        }

        return tl.get();
    }

    /**
     * 使用ThreadLocal<SimpleDateFormat>来获取SimpleDateFormat,这样每个线程只会有一个SimpleDateFormat
     * 如果新的线程中没有SimpleDateFormat，才会new一个
     */
    public String format(Date date, String pattern) {
        return getSdf(pattern).format(date);
    }

    public Date parse(String dateStr, String pattern) throws ParseException {
        return getSdf(pattern).parse(dateStr);
    }

    /**
     * 计算参数时间戳 与 当前时间的天数差
     * 只取时间戳中的月日 与当前年份进行拼接 得到 今年的该月该日
     * 今年的该月该日 与 当前时间计算 得出  天数差
     * 如果今年的该月该日 已过 那么就计算明年的该月该日 与当前时间的 天数差
     * @param dateSql
     * @return
     */
   public static Integer  getCountdownDays(Date dateSql,Integer type){

        //获取数据库中对应的时间戳对应的月日 并 附加到今年上面
        String stringTimeNow = getStringTime(new Date()).substring(0, 4);
        String stringTimeSql = getStringTime(dateSql).substring(4);
        stringTimeSql=stringTimeNow+stringTimeSql;
        //得到拼接好的数据库时间戳   这里存在一个问题 如 2-29号 如果当前没有2.29号 那么会自动向后一天
        Long timeSqlDate = getTimestamp(stringTimeSql);
        Long timeNowDate = getTimestamp(getStringTime(new Date()));
        int timeDistance;
        if (type==1){
            timeDistance= getTimeDistance(new Date(timeSqlDate),new Date(timeNowDate));

        }else {
            timeDistance= getTimeDistance(new Date(timeNowDate), new Date(timeSqlDate));
          }

        if (timeDistance == 0 ){
            //当前就位 纪恋日
            return 0;
        }else if (timeDistance>0){
            //纪恋日还没有到
            return timeDistance;
        }else {
            //纪恋日已过 自动加一年计算
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(new Date(timeSqlDate));
            calendar.add(Calendar.YEAR, 1);//增加一年
            timeSqlDate= calendar.getTime().getTime();
            return     getTimeDistance(new Date(timeNowDate), new Date(timeSqlDate));
        }
    }
    public static int getTimeDistance(Date beginDate , Date endDate ) {
        Calendar beginCalendar = Calendar.getInstance();
        beginCalendar.setTime(beginDate);
        Calendar endCalendar = Calendar.getInstance();
        endCalendar.setTime(endDate);
        long beginTime = beginCalendar.getTime().getTime();
        long endTime = endCalendar.getTime().getTime();
        int betweenDays = (int)((endTime - beginTime) / (1000 * 60 * 60 *24));//先算出两时间的毫秒数之差大于一天的天数
        endCalendar.add(Calendar.DAY_OF_MONTH, -betweenDays);//使endCalendar减去这些天数，将问题转换为两时间的毫秒数之差不足一天的情况
        endCalendar.add(Calendar.DAY_OF_MONTH, -1);//再使endCalendar减去1天
        if(beginCalendar.get(Calendar.DAY_OF_MONTH)==endCalendar.get(Calendar.DAY_OF_MONTH))//比较两日期的DAY_OF_MONTH是否相等
            return betweenDays + 1;	//相等说明确实跨天了
        else
            return betweenDays;	//不相等说明确实未跨天
    }
    /**
     * @desc 字符串转时间戳
     * @param
     * @example time="2019-04-19 00:00:00"
     **/
    public static Long getTimestamp(String time) {
        Long timestamp = null;
        try {
            timestamp = new SimpleDateFormat("yyyy-MM-dd").parse(time).getTime();
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return timestamp;
    }
    /**
     * @desc  时间戳转字符串
     * @param
     * @example timestamp=1558322327000
     **/
    public static String getStringTime(Date timestamp) {
        return new SimpleDateFormat("yyyy-MM-dd").format(timestamp.getTime());
    }

    /**
     * @desc  时间戳转字符串
     * @param
     * @example timestamp=1558322327000
     **/
    public static String getStringTimeMore(Date timestamp) {
        return new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(timestamp.getTime());
    }

    //获取过去或未来任意天内的日期数组(特别定制，去除当前一天)
    public List<String> getDateList(int days){
        List<String> list = new ArrayList<>();

        int days_temp = Math.abs(days);     //对不确定正负的days取绝对值
        Calendar calendar = Calendar.getInstance();
        if(days > 0){   //表示需要的是未来几天的数据
            calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) + days_temp);
            for(int i = 1; i < days_temp; i++){
                calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) - 1);
                String str_date = this.format(calendar.getTime(),"yyyy-MM-dd");
                list.add(str_date);
            }
        }else {     //表示需要的是过去几天的数据
            calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) - days_temp);
            for(int i = 1; i < days_temp; i++){
                calendar.set(Calendar.DAY_OF_YEAR, calendar.get(Calendar.DAY_OF_YEAR) + 1);
                String str_date = this.format(calendar.getTime(),"yyyy-MM-dd");
                list.add(str_date);
            }
        }

        return list;
    }

    /**
     * 获取今天开始时间
     */
    public static Long getStartTime() {
        Calendar todayStart = Calendar.getInstance();
        todayStart.set(Calendar.HOUR_OF_DAY, 0);
        todayStart.set(Calendar.MINUTE, 0);
        todayStart.set(Calendar.SECOND, 0);
        todayStart.set(Calendar.MILLISECOND, 0);
        return todayStart.getTime().getTime();
    }

    /**
     * 获取今天结束时间
     */
    public static Long getEndTime() {
        Calendar todayEnd = Calendar.getInstance();
        todayEnd.set(Calendar.HOUR_OF_DAY, 23);
        todayEnd.set(Calendar.MINUTE, 59);
        todayEnd.set(Calendar.SECOND, 59);
        todayEnd.set(Calendar.MILLISECOND, 999);
        return todayEnd.getTime().getTime();
    }
    public static String dealDateFormat(String oldDate) {
        Date date1 = null;
        DateFormat df2 = null;
        try {
            oldDate= oldDate.replace("Z", " UTC");
            DateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS Z");
            Date date = df.parse(oldDate);
            SimpleDateFormat df1 = new SimpleDateFormat ("EEE MMM dd HH:mm:ss Z yyyy", Locale.UK);
            date1 = df1.parse(date.toString());
            df2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return df2.format(date1);
    }
    /**
     * start
     * 本周开始时间戳 - 以星期一为本周的第一天
     */
    public static long getWeekStartTime() {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat( "yyyyMMdd", Locale. getDefault());
        Calendar cal = Calendar.getInstance();
        cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONDAY), cal.get(Calendar.DAY_OF_MONTH), 0,
                0, 0);
        int day_of_week = cal.get(Calendar. DAY_OF_WEEK) - 1;
        if (day_of_week == 0 ) {
            day_of_week = 7 ;
        }
        cal.add(Calendar.DATE , -day_of_week + 1 );
        return  cal.getTime().getTime();
    }
    /**
     * end
     * 本周结束时间戳 - 以星期一为本周的第一天
     */
    public static long getWeekEndTime() {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat( "yyyyMMdd", Locale. getDefault());
        Calendar cal = Calendar.getInstance();
        cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONDAY), cal.get(Calendar.DAY_OF_MONTH), 23,
                59, 59);
        int day_of_week = cal.get(Calendar. DAY_OF_WEEK) - 1;
        if (day_of_week == 0 ) {
            day_of_week = 7 ;
        }
        cal.add(Calendar.DATE , -day_of_week + 7 );
        return  cal.getTime().getTime() ;
    }

    /**
     * 获取当月开始时间戳
     *
     * @param timeStamp 毫秒级时间戳
     * @param
     * @return
     */
    public static Long getMonthStartTime(Long timeStamp) {
        Calendar calendar = Calendar.getInstance();// 获取当前日期
        calendar.setTimeInMillis(timeStamp);
        calendar.add(Calendar.YEAR, 0);
        calendar.add(Calendar.MONTH, 0);
        calendar.set(Calendar.DAY_OF_MONTH, 1);// 设置为1号,当前日期既为本月第一天
        calendar.set(Calendar.HOUR_OF_DAY, 0);
        calendar.set(Calendar.MINUTE, 0);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return calendar.getTimeInMillis();
    }

    /**
     * 获取当月的结束时间戳
     *
     * @param timeStamp 毫秒级时间戳
     * @param
     * @return
     */
    public static Long getMonthEndTime(Long timeStamp) {
        Calendar calendar = Calendar.getInstance();// 获取当前日期
        calendar.setTimeInMillis(timeStamp);
        calendar.add(Calendar.YEAR, 0);
        calendar.add(Calendar.MONTH, 0);
        calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));// 获取当前月最后一天
        calendar.set(Calendar.HOUR_OF_DAY, 23);
        calendar.set(Calendar.MINUTE, 59);
        calendar.set(Calendar.SECOND, 59);
        calendar.set(Calendar.MILLISECOND, 999);
        return calendar.getTimeInMillis();
    }
}