PHP 处理日期的常用方法

<?php
/**
* util for date
*/
class DateUtil
{

/**
* @return Date of last monday
*/
public static function lastMonday($date = null)
{
if(!isset($date))
{
$date = date('Y-m-d');
}

$first = 1;
$index = date('w', strtotime($date));//the index of today in this week, sunday is 0, and so on
$d = $index ? $index - $first : 6;
return date('Y-m-d', strtotime($date . '-' . $d . 'days'));
}

/**
* $n Integer
* @return last $n monday date
*/
public static function lastNMondayDates($n = 4)
{
$result = array();
$n = intval($n);
$n = ($n < 1) ?  4 : $n;
$lastMonday = self::lastMonday();

for ($i = $n - 1; $i >= 0; --$i)
{
$result[] = date('Y-m-d', strtotime($lastMonday . '-' . ($i * 7) . 'days'));
}

return $result;
}

/**
* @return date of tomorrow, eg.2013-09-06
*/
public static function tomorrow()
{
return date('Y-m-d', strtotime('+1 day'));
}

/**
* @return date of today, eg.2013-09-06
*/
public static function today()
{
return date('Y-m-d');
}

/**
* Get the date of yesterday
* If $date is special, it will return the day before $date
* @return date of yesterday, eg.2013-09-06
*/
public static function yesterday($date = null)
{
$time = isset($date) ? strtotime($date) : 0;

return date('Y-m-d', $time + strtotime('-1 day'));
}

/**
* Return the week of special date
* 0 means Sunday, 1 means Monday and so one
* @param String $date
* @return Int : the index of today in this week, sunday is 0, and so on
*/
public static function weekOfDate($date)
{
return date('w', strtotime($date));
}

/**
*
* This function used to get a period of date
* @example
* if today is 2013-09-06. $start = 2, $end = 4
* returns array('2013-09-08', '2013-09-09', '2013-09-10')
*
* @param Integer $start
* @param Integer $end
* @param Boolean $isMongoDate: default false, if true, if will return Mongo date array, or it will return php date list
* @return array date list
*/
public static function nextPeriodDate($start, $end, $isMongoDate = false)
{
$result = array();
$start = intval($start);
$end = intval($end);

if($start > $end)
{
return $result;
}

for ($i = $start; $i <= $end; $i++)
{
if($isMongoDate)
{
$date = date('Y-m-d', strtotime('+' . $i . 'day'));
$result[] = new MongoDate(strtotime($date));
}
else
{
$result[] = date('Y-m-d', strtotime('+' . $i . 'day'));
}
}

return $result;
}

/**
* Get the Nth date from today
* @param number $n: 1
* @param String $date: e.g 2013-10-15
* @return String: e.g 2013-10-16
* @example
* if today is 2013-09-06, $n = 2 return 2013-09-08
*/
public static function nextNDate($n, $date = null)
{
if(!isset($date))
{
return date('Y-m-d', strtotime('+' . intval($n) . 'day'));
}
else
{
return date('Y-m-d', strtotime($date) + 60 * 60 * 24 * $n);
}
}

/**
* Get the date of special date's week
* If $date is special, it will compute from $date, or it will compute from current date
* @param int $week: 0 means sunday, 1 means monday and so on
* @param String $date
* @return string
*/
public static function nextWeek($week, $date = null)
{
$weeks = array('sunday', 'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday');
if(!isset($date))
{
$date = date('Y-m-d');
}

return date('Y-m-d', strtotime('next ' . $weeks[$week] , strtotime($date)));
}

/**
* Get the date of special week of special month
* @example
* If $weekIndex is 2,$week is 0, $monthIndex is 0, the function will return the date of second Sunday of this month
* If $weekIndex is 1,$week is 1, $monthIndex is 1, the function will return the date of first Monday of next month
* Notice:$monthIndex range is 0-11, if $monthIndex is not in this rang, it will return '1970-01-01'
* @param int $weekIndex: 0 means first week, 1 means second week and so on
* @param int $week: 0 means sunday, 1 means monday and so on
* @param int $monthIndex: 0 means this monthday, 1 means next month and so on
* @return String
*/
public static function dateOfMonthWeek($weekIndex, $week, $monthIndex = 0)
{
$weeks = array('sunday', 'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday');
$weekIndexs = array('first', 'second', 'third', 'fourth');
$monthIndexs = array('this', 'first', 'second', 'third', 'fourth', 'fifth', 'sixth', 'seventh',
'eighth', 'ninth', 'tenth', 'eleventh', 'twelfth');

return date('Y-m-d', strtotime($weekIndexs[$weekIndex] .' '. $weeks[$week] . ' of ' . $monthIndexs[$monthIndex] .' month'));
}

/**
* Get date string from a MongoDate
* @param MongoDate $date
*/
public static function convertMongoDate($date, $format = 'Y-m-d')
{
if(!isset($date))
{
return '';
}

return date($format, $date->sec);
}

/**
* Date validation
* @param string $dateStr
* @return boolean: true means is date format, false means not
*/
public static function isDate($dateStr, $includeTime = false)
{
try
{
$date = new DateTime(trim($dateStr));
}
catch(Exception $e) {
return false;
}

$month = $date->format('m');
$day = $date->format('d');
$year = $date->format('Y');

if(!checkdate($month, $day, $year))
{
return false;
}

if($includeTime)
{
$strArr = explode(' ', $dateStr);
$strTime = explode(':', $strArr[1]);

if(count($strArr) != 2)
{
return false;
}

if(count($strTime) != 3)
{
return false;
}
}

return true;
}

/**
* Get the week of every month for special date
* If $date is null, it will compute by current date
* The return is like 'm-2-1', and it means second Monday every month
* @param String $date
* @return string
*/
public static function getWeekMonthly($date = null)
{
if(!isset($date))
{
$date = date('Y-m-d');
}

$wk_day = date('w', strtotime($date));
$date_now = date('j', strtotime($date));
$wkday_array = array(0, 1, 2, 3, 4, 5, 6);

$cal_result = ceil($date_now / 7);

return 'm-' . $cal_result . '-' . $wkday_array[$wk_day];
}

/**
* Get the weekIndex of every week for special date
* @example:
* If $date is '2013-10-11' and it will return 'w-5', it means Friday of every week
* @param String $date
* @return string
*/
public static function getWeekOfDate($date = null)
{
if(!isset($date))
{
$date = date('Y-m-d');
}

return 'w-' . date('w', strtotime($date));
}

/**
* Get next $n hours time, positive or negative is allowed for $n
* @param number $n
* @param Date $date:optional, default is current time
* @return string
*/
public static function nextNHours($n, $date = null)
{
if(!isset($date))
{
$date = date('Y-m-d H:i:s');
}

return date('Y-m-d H:i:s', strtotime($date) + (60 * 60 * $n));
}
}