PHP Calendar简单的小程序

<?php
    /**
    * @Name ExampleCalendar.php
    * @Desc Simple canendar program
    *
    * @Version    1.1
    * @Author     Bian Yuan
    * @Email     [email protected]
    * @Since     2009/04/30
    */
    session_start();
    function html_select($name, $options=array(), $firstValue="Please Select", $default="", $onchange=""){
        if(empty($onchange)){
            $select = "<select name='".$name."' id='".$name."'>";
        }else{
            $select = "<select name='".$name."' id='".$name."' onchange=\"".$onchange."\" >";
        }
        if($firstValue != ''){
            $select .= "<option value='-1'>".$firstValue."</option>";
        }
        foreach($options as $k=>$v){
            if($default == $v){
                $select .= "<option value='".$k."' selected='selected'>$v</option>";
            }else{
                $select .= "<option value='".$k."'>$v</option>";
            }
        }
        $select .= "</select>";
        return $select;
    }
    class Calendar
    {
        private $year;
        private $month;
        
        private $week = array(
         'Sunday' => '星期日',
         'Monday' => '星期一',
         'Tuesday' => '星期二',
         'Wednesday' => '星期三',
         'Thursday' => '星期四',
         'Friday' => '星期五',
         'Saturday' => '星期六'
        );
        private $data = array(
        
        );
        /**
         * @desc    Calendar构造方法
        **/
     public function __construct($year='', $month='')
     {
         $this->year = $year == '' ? date('Y') : intval($year);
         $this->month = $month == '' ? date('n') : intval($month);
     }
     public function setData($info=array())
     {
            $this->data = $info;
     }
     /**
         * @desc     获得这个月的第一天是星期几
        **/
     public function getFirstDayOfMonth()
     {
         return date("w", mktime(0, 0, 0, $this->month, 1, $this->year));
     }
     /**
         * @desc    获得这个月有多少天
        **/
     public function getDaysInMonth()
     {
         return date("t", mktime(0, 0, 0, $this->month, 1, $this->year));
     }
     public function getCalendar()
     {
         $s = "<table style='font-size:12px;' id='calendar' width='100%' border='1' cellpadding='0' cellspacing='0'>\n";
         $s .= "<thead>\n<tr>\n";
         foreach ($this->week as $item)
         {
             $s .= "<td>{$item}</td>\n";
         }
         $s .= "</tr>\n</thead>\n<tbody>\n<tr>\n";
         
         $t = $this->getDaysInMonth();
            $nowDay = date('Ynd');
         for($day=1; $day<=$t; $day++)
         {
             if(array_key_exists($this->year ."-". $this->month . "-" . $day, $this->data))
             {
                 $info = '<ul>';
                 if(! empty($this->data[$this->year ."-". $this->month . "-" . $day]))
                 {
                     foreach ($this->data[$this->year ."-". $this->month . "-" . $day] as $item)
                     {
                         $info .= "<li>{$item}</li>";
                     }
                 }
                 $info .= '</ul>';
             }
             // Set day bgcolor

             if($this->year.$this->month.$day == $nowDay)
             {
                 $dayBgColor = 'blue';
             }else{
                 $dayBgColor = 'yellow';
             }
             if(1 == $day)
             {
                 $firstDayOfMonth = $this->getFirstDayOfMonth();
                 $s .= str_repeat("<td>&nbsp</td>\n", $firstDayOfMonth);
             }
             $day_in_week_pos = $w = date("w",mktime(0,0,0,$this->month, $day, $this->year));
                if(6 == $w)
                {
                    $s .= "<td bgcolor='".$dayBgColor."'>{$day}{$info}</td>\n</tr>\n";
                }else{
                    $s .= "<td bgcolor='".$dayBgColor."'>{$day}{$info}</td>\n";
                }
                unset($info);
         }
         
            $s .= str_repeat("<td>&nbsp;</td>\n", 6-$day_in_week_pos);
         $s .= "</tr></tbody>\n</table>\n";
         return $s;
     }
    }
    
    // Make year select options

    for($year=2007; $year <=2020; $year++) {
        $yearOption[$year] = $year;
    }
    // Make month select options

    for($month=1; $month<=12; $month++){
        $monthOption[$month] = $month;
    }
    
    $year = isset($_GET['year']) ? intval($_GET['year']) : date('Y');
    $month = isset($_GET['month']) ? intval($_GET['month']) : date('n');

    
    $yearOnChange = "window.location.href='?year='+this.value+'&month={$month}'";
    $monthOnChange = "window.location.href='?month='+this.value+'&year={$year}'";
    
    echo html_select('year', $yearOption, '', $year, $yearOnChange);
    echo html_select('month', $monthOption, '', $month, $monthOnChange);
    
    if(isset($_POST['submit']))
    {
        $y = intval($_POST['y']);
        $m = intval($_POST['m']);
        $d = intval($_POST['d']);
        if(!checkdate($m,$d,$y))
        {
            die('error date');
        }
        $date = $y.'-'.$m.'-'.$d;
        $_SESSION['data'][$date][] = strip_tags($_POST['info']);
    }
    
    $calendar = new Calendar($year, $month);
    if(!isset($_SESSION['data']))
    {
     $_SESSION['data'] = array(
            '2009-4-28' => array('有些事吧。。。','今天几号？','事情三'),
            '2009-4-29' => array('反正就是闹心','事情二'),
            '2009-4-30' => array('按照自己的想法写，愿咋写怎么写。')
        );
    }
    $calendar->setData($_SESSION['data']);
    echo $calendar->getCalendar();
?>
<form method="post" action="">
    <input name="y" type="text" />年
    <input name="m" type="text" />月
    <input name="d" type="text" />日
    <input name="info" type="text" />事情
    <input type="submit" name="submit">
</form>