ThinkPHP 获取指定日期后第N个工作日具体日期

思路：

1、获取到查询年份内所有工作日数据数组
2、获取到查询开始日期在工作日的索引
3、计算需查询日期索引
4、获得查询日期

 /*创建日期类型记录表格*/
 CREATE TABLE `tb_workday` (
 `did` int(11) NOT NULL AUTO_INCREMENT,
 `exact_date` varchar(32) NOT NULL COMMENT '具体日期：格式date("Ymd");(20170205)',
 `date_year` varchar(32) NOT NULL COMMENT '具体日期：格式date("Y");(2017)',
 `date_type` tinyint(2) NOT NULL COMMENT '日期类型：0、工作日；1、特殊工作日；2、法定节假日',
 PRIMARY KEY (`did`)
 ) ENGINE=InnoDB AUTO_INCREMENT=829 DEFAULT CHARSET=utf8 COMMENT='各年工作日&法定节假日数据'

 <?php

 class work_days
 {
   /**
    * 获取星期
    * @param $date
    * @return mixed
    */
   function get_week($date)
   {
     //强制转换日期格式
     $date_str = date('Y-m-d', strtotime($date));
     //封装成数组
     $arr = explode("-", $date_str);
     //参数赋值
     //年
     $year = $arr[0];
     //月，输出2位整型，不够2位右对齐
     $month = sprintf('%02d', $arr[1]);
     //日，输出2位整型，不够2位右对齐
     $day = sprintf('%02d', $arr[2]);
     //时分秒默认赋值为0；
     $hour = $minute = $second = 0;
     //转换成时间戳
     $strap = mktime($hour, $minute, $second, $month, $day, $year);
     //获取数字型星期几
     $number_wk = date("w", $strap);

     //获取数字对应的星期
     return $number_wk;

     //自定义星期数组
     //$weekArr = array("星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六");

     //获取数字对应的星期
     //return $weekArr[$number_wk];
   }

   /**
    * 获取指定日期段内每一天的日期
    * @param  string $startdate 开始日期
    * @param  string $enddate   结束日期
    * @return array
    */
   function getDateFromRange($startdate, $enddate)
   {
     $stimestamp = strtotime($startdate);
     $etimestamp = strtotime($enddate);

     // 计算日期段内有多少天
     $days = ($etimestamp - $stimestamp) / 86400 + 1;

     // 保存每天日期
     $_list_date = array();
     for ($i = 0; $i < $days; $i++) {
       $_list_date[] = date('Y-m-d', $stimestamp + (86400 * $i));
     }
     return $_list_date;
   }

   function curl_post($url, $data = null)
   {
     $curl = curl_init();
     curl_setopt($curl, CURLOPT_URL, $url);
     curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);
     curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE);
     if (!empty($data)) {
       curl_setopt($curl, CURLOPT_POST, 1);
       curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
     }
     curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
     $output = curl_exec($curl);
     curl_close($curl);
     return $output;
   }

   /**
    * 更新数据库指定年份日期数据
    * @param $year
    * @return int
    */
   function updateDate($year)
   {
     $startDate = date('Y-m-d', strtotime($year . '-01-01'));
     $endDate = date('Y-m-d', strtotime('+1 year', strtotime($startDate)) - 86400);
     $_list_date = self::getDateFromRange($startDate, $endDate);

     $url = 'http://api.goseek.cn/Tools/holiday';//自行查找的免费API

     $m = M('tb_workday');
     $count = 0;

     foreach ($_list_date as $k => $_date) {
       $_ret = 0;
       $_date = date('Ymd', strtotime($_date));
       $_post_data = array('date' => $_date);
       $_ret_curl = curl_post($url, $_post_data);
       $_ret_curl = json_decode($_ret_curl, true);

       //工作日
       if ($_ret_curl['data'] == 0) {
         $dateData['exact_date'] = $_date;
         $dateData['date_year'] = $year;
         $dateData['date_type'] = 0;
         $_ret = $m->add($dateData) ? 1 : 0;
         unset($dateData);

         //工作日 判断是否为周末
         if (in_array(self::get_week($_date), array(0, 1))) {
           //特殊工作日
           $dateData['exact_date'] = $_date;
           $dateData['date_year'] = $year;
           $dateData['date_type'] = 1;
           $_ret = $m->add($dateData) ? 1 : 0;
           unset($dateData);
         }
       }

       //法定节假日
       if ($_ret_curl['data'] == 2) {
         $dateData['exact_date'] = $_date;
         $dateData['date_year'] = $year;
         $dateData['date_type'] = 2;
         $_ret = $m->add($dateData) ? 1 : 0;
         unset($dateData);
       }

       //休息日(周末) 暂不处理
       /*if ($_ret_curl['data'] == 1) {

       }*/
       $_ret && $count++;
       unset($_date, $_post_data, $_ret_curl, $_ret);
     }
     return $count;
   }

   /**
    * 获取当年所有工作日 (从数据库获取，数据库无数据则先更新数据)
    * @param string $year 当年年份
    * @return array
    */
   private function getWorkDays($year)
   {
     $m = M('tb_workday');
     $map['date_year'] = $year;
     $map['date_type'] = 0;
     $DateArray = $m->field('exact_date')->where($map)->select();
     if (!empty($DateArray)) {
       $DateArray = array_column($DateArray, 'exact_date');
       return $DateArray;
     } else {
       //更新数据库工作日数据
       $ret = self::updateDate($year);
       if ($ret > 0) {
         return self::getWorkDays($year);
       } else {
         return false;
       }
     }
   }

   /**
    * 获取开始日期后第N个工作日具体日期
    * @param $startdate string 计算开始日期  需包含年月日信息
    * @param $days      int 间隔天数
    * @return mixed 成功返回 对应日期，失败返回false
    */
   public function getNextWorkDate($startdate, $days)
   {
     $year = date('Y', strtotime($startdate));
     $startdate = date('Y-m-d', strtotime($startdate));

     $workDays = $this->getWorkDays($year);

     $search_key = array_search(date('Ymd', strtotime($startdate)), $workDays);

     if ($search_key === false) {//查询日期为非工作
       //获取查询日期前最近工作日
       $m = M('tb_workday');
       $map['date_year'] = $year;
       $map['date_type'] = 0;
       $map['DATE_FORMAT(`exact_date`,\'%Y-%m-%d\')'] = array('LT', $startdate);
       $_search_date = $m->where($map)->order('`exact_date` DESC')->getField('exact_date');
       $search_key = array_search($_search_date, $workDays);
       unset($m, $map, $_search_date);
     }

     $t_key = $search_key + $days;

     if ($t_key <= count($workDays) - 1) {
       return date('Y-m-d', strtotime($workDays[$t_key]));
     } else {
       //查询日期已跨年
       $n_days = $days - (count($workDays) - 1 - $search_key);
       $next_year = $year + 1;
       return $this->getNextWorkDate($next_year . '-01-01', $n_days - 1);
     }
   }
 }

 $startdate = '2018-09-28';
 $days = 5;

 $class = new work_days();
 $_date_workday = $class->getNextWorkDate($startdate, $days);
 echo $_date_workday;//2018-10-10