JAVA一些常用的时间操作

项目中经常有对时间进行处理的需求，下面是一些常用的操作整理，方便以后再次使用以及做相关复习。

1.字符串转换为日期

  /**
      * 字符串转换为日期
      * @param dateStr 需要转换的日期
      * @param dateFormat 日期格式yyyy-MM-dd/yyyy-MM-dd HH:mm:ss
      */
     public static Date toDate(String dateStr, SimpleDateFormat dateFormat) throws ParseException{
         Date date = null;
         try {
             date = dateFormat.parse(dateStr);
         } catch (ParseException e) {
             logger.debug("Fail to convert String to Date, {}", dateStr);
         }
         return date;
     }

2.时间戳转日期

    /**
     * 时间戳转日期
     * @param date
     * @return
     */
    public static String dateToTime(long time, SimpleDateFormat dateFormat) throws ParseException{
         String data = null;
         try {
             dateFormat.format(new Date(time*1000));
         } catch (Exception e) {
             logger.debug("Fail to convert long to Date, {}", time);
         }
         return data;
    }

3.日期格式化成字符串

    /**
     * 日期格式化成字符串
     * @param date
     * @param dateFormat
     * @return
     * @throws ParseException
     */
    public static String toString(Date date, SimpleDateFormat dateFormat) throws ParseException{
        return dateFormat.format(date);
    }

4.获取指定日期之前或之后的日期 ，十分秒为00:00:00

    /**
     * 获取指定日期之前或之后的日期
     * @param date
     * @param num 正数为之后，负数为之前
     * @return yyyy-MM-dd 00:00:00
     */
    public static Date getSpecificDate(Date date, int num){
        Calendar todayCal = Calendar.getInstance();
        todayCal.setTime(date);

        Calendar c = Calendar.getInstance();
        c.set(todayCal.get(Calendar.YEAR), todayCal.get(Calendar.MONTH), todayCal.get(Calendar.DAY_OF_MONTH) + num, 0, 0, 0);
        return c.getTime();
    }

5.获取指定日期之前或之后的日期 ，时分秒为当前的

    /**
     * 获取指定日期之前或之后的日期
     * @param date
     * @param num 正数为之前，负数为之后
     * @return yyyy-MM-dd + 当前的时分秒
     */
    public static Date getSpecificDateAndHhMmSs(Date date,int num){
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        int day=c.get(Calendar.DATE);
        c.set(Calendar.DATE,day - num);
        return c.getTime();
    }

6.将time类型的时间字符串 转换成 时、分

    /**
     * 将time类型的时间字符串 转换成 时、分
     * HH-mm-ss -->>  HH-mm
     * @param time
     * @return
     */
    public static String timeToHHMM(String time){
        return time.substring(0, time.length() - 3);
    }

7.获取某个日期的时、分

    /**
     * 获取某个日期的时、分
     * @param date
     * @return HH-mm
     */
    public static String getHM(Date date){
        Calendar ca = Calendar.getInstance();
        ca.setTime(date);
        Integer hour = ca.get(Calendar.HOUR_OF_DAY);//小时
        Integer minute = ca.get(Calendar.MINUTE);//分
        String rs_hour = hour.toString();
        String rs_minute = minute.toString();

        if (rs_hour.length() == 1){
            rs_hour = "0" + hour;
        }
        if(rs_minute.length() == 1){
            rs_minute = "0" + minute;
        }

        return rs_hour + ":" + rs_minute;
    }

8.time类型的时间字符串 -->> 零点开始的秒数

    /**
     * time类型的时间字符串 -->> 零点开始的秒数
     * @param time HH-mm / HH-mm-ss
     * @return
     */
    public static Integer timeToSeconds(String time){
          String[] timeSplit = null;
          int hours = 0,minutes = 0,seconds = 0;
          try {
              timeSplit = time.split(":");
              if (timeSplit.length == 2) {
                  hours = Integer.valueOf(timeSplit[0])*60*60;
                  minutes = Integer.valueOf(timeSplit[1])*60;
              }else if(timeSplit.length == 3){
                  hours = Integer.valueOf(timeSplit[0])*60*60;
                  minutes = Integer.valueOf(timeSplit[1])*60;
                  seconds = Integer.valueOf(timeSplit[2]);
              }else{
                  logger.debug("Fail to convert the time, {}", time);
              }
          } catch (Exception e) {
              logger.debug("Fail to convert the time, {}", time);
              throw e;
          }

        return hours + minutes + seconds;
    }

9.零点开始的秒数转时间 -->> HH-mm-ss

    /**
     * 零点开始的秒数转时间 -->> HH-mm-ss
     * @param durationSeconds
     * @return
     */
    public static String getDuration(int durationSeconds){
        int hours = durationSeconds /(60*60);
        int leftSeconds = durationSeconds % (60*60);
        int minutes = leftSeconds / 60;
        int seconds = leftSeconds % 60;  

        StringBuffer sBuffer = new StringBuffer();
        sBuffer.append(addZeroPrefix(hours));
        sBuffer.append(":");
        sBuffer.append(addZeroPrefix(minutes));
        sBuffer.append(":");
        sBuffer.append(addZeroPrefix(seconds));  

        return sBuffer.toString();
    }  

    public static String addZeroPrefix(int number){
        if(number < 10)
            return "0"+number;
        else
            return ""+number;
    }

10.比较两个日期相差的秒数

    /**
     * 比较两个日期相差的秒数
     * @param startDate
     * @param endDate
     * @return
     */
    public static int getTimeSeconds(Date startDate,Date endDate) {
          long a = endDate.getTime();
          long b = startDate.getTime();
          return (int)((a - b) / 1000);
    }

11.判断两个时间段是否存在交集

    /**
     * 比较两个日期相差的秒数
     * @param startDate
     * @param endDate
     * @return
     */
    public static int getTimeSeconds(Date startDate,Date endDate) {
          long a = endDate.getTime();
          long b = startDate.getTime();
          return (int)((a - b) / 1000);
    }

12.获取指定日期是星期几(1-7分别代表周一至周日)

    /**
     * 获取指定日期是星期几(1-7分别代表周一至周日)
     * @return
     */
    public static int DayOfWeek(Date date){
        Calendar now = Calendar.getInstance();
        now.setTime(date);
        boolean isFirstDay = (now.getFirstDayOfWeek() == Calendar.SUNDAY);
        int weekday = now.get(Calendar.DAY_OF_WEEK);
        if(isFirstDay){
            weekday = weekday - 1;
            if(weekday == 0){
                weekday = 7;
            }
        }
        return weekday;
    }