由于工作上用到发送上一个月，上一周这中获取时间的部分，所以找了个工具类记录下
/**
* 计算两个时间相隔的天数
* @param date1
* @param date2
* @return
*/
public static int differentDaysByMillisecond(Date date1, Date date2) {
try{
return (int) ((date2.getTime() - date1.getTime()) / (1000 * 3600 * 24));
}catch (Exception e){
return 0;
}
}

/**
 * 计算两个时间相隔的天数
 * @param date1
 * @param date2
 * @return
 */
public static float differentHoursByMillisecond(Date date1, Date date2) {
    float hours = (float) ((date2.getTime() - date1.getTime()) / (1000 * 3600.0));
    return hours;
}

/**
 * 判断日期是否为节假日
 *
 * @return
 * @throws ApiException
 */
public static Integer isWork(String time) throws ParseException {

    String httpArg = dateToWork(time);

    BufferedReader reader = null;
    String result = null;
    StringBuffer sbf = new StringBuffer();

    Integer data = null;
    try {
        URL url = new URL(CHECKISWORKDAY + httpArg);
        HttpURLConnection connection = (HttpURLConnection) url
                .openConnection();
        connection.setRequestMethod("GET");
        connection.connect();
        InputStream is = connection.getInputStream();
        reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
        String strRead = null;
        while ((strRead = reader.readLine()) != null) {
            sbf.append(strRead);
            sbf.append("\r\n");
        }
        reader.close();
        result = sbf.toString();
        Map<String, Object> parse = (Map) JSON.parse(result);
        data = (Integer) parse.get("data");
    } catch (Exception e) {
        e.printStackTrace();
    }
    return data;
}

/**
 * 计算小时
 *
 * @param on
 * @param off
 * @return
 */
public static double dateToDouble(Date on, Date off) {
    long l = off.getTime() - on.getTime();//毫秒

// long l1 = l / 1000;//秒
// long l2 = l1 / 60;//分钟
// long l3 = l2 / 60;//小时
return l / 1000 / 60 / 60.0;
}

/**
 * 判断是否是工作日的格式
 *
 * @return
 */
public static String dateToWork(String time) throws ParseException {
    Date date = stringToDate(time);
    SimpleDateFormat f = new SimpleDateFormat("yyyyMMdd");
    return f.format(date);
}

/**
 * 获取昨天的时间
 *
 * @return
 */
public static String getYesterday(Date date) {
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    cal.add(Calendar.DATE, -1);
    Date time = cal.getTime();
    String format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(time);
    return format;
}


/**
 * 获取现在的时间
 *
 * @return
 */
public static String dataToString(Date date) {
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    Date time = cal.getTime();
    String format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(time);
    return format;
}


/**
 * 字符串转date
 */
public static Date stringToDate(String time) throws ParseException {
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    return sdf.parse(time);
}
/**
 * 字符串转date2
 */
public static Date stringToDate2(String time) throws ParseException {
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm");
    return sdf.parse(time);
}

/**
 * 获取昨天上班的时间
 *
 * @return
 */
public static Date getYesterdayOnDutyTime(Date time) throws ParseException {
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
    Calendar date = Calendar.getInstance();
    date.setTime(time);
    date.set(Calendar.DATE, date.get(Calendar.DATE) - 1);
    String yesterdayOnDutyTime = sdf.format(date.getTime()) + " 09:00:00";

    DateFormat df = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
    return df.parse(yesterdayOnDutyTime);
}

/**
 * 获取零点时间
 *
 * @return
 */
public static Date getTimeZero(Date time) throws ParseException {
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
    Calendar date = Calendar.getInstance();
    date.setTime(time);
    date.set(Calendar.DATE, date.get(Calendar.DATE));
    String yesterdayOnDutyTime = sdf.format(date.getTime()) + " 00:00:00";

    DateFormat df = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
    return df.parse(yesterdayOnDutyTime);
}

/**
 * 获取7天前上班的时间
 *
 * @return
 */
public static Date getDutyTimeLastWork(Date time) throws ParseException {
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
    Calendar date = Calendar.getInstance();
    date.setTime(time);
    date.set(Calendar.DATE, date.get(Calendar.DATE) - 7);
    String yesterdayOnDutyTime = sdf.format(date.getTime()) + " 09:00:00";

    DateFormat df = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
    return df.parse(yesterdayOnDutyTime);
}



/**
 * 获取昨天下班的时间
 *
 * @return
 */
public static Date getYesterdayOffDutyTime(Date time) throws ParseException {
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
    Calendar date = Calendar.getInstance();
    date.setTime(time);
    date.set(Calendar.DATE, date.get(Calendar.DATE) - 1);
    String yesterdayOnDutyTime = sdf.format(date.getTime()) + " 18:00:00";

    DateFormat df = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
    return df.parse(yesterdayOnDutyTime);

}

/**
 * 天数加一
 */
public static String getNextDay(String time) throws ParseException {
    Date date = stringToDate(time);
    Calendar cal = Calendar.getInstance();
    cal.setTime(date);
    cal.add(Calendar.DATE, 1);
    Date time1 = cal.getTime();
    String format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(time1);
    return format;
}