用PHP生成日历

<?php
class Calendar
{
    private $year;
    private $month;
    private $weeks  = array(&#39;日&#39;,&#39;一&#39;,&#39;二&#39;,&#39;三&#39;,&#39;四&#39;,&#39;五&#39;,&#39;六&#39;);
    
    function __construct($options = array()) {
        $this->year = date(&#39;Y&#39;);
        $this->month = date(&#39;m&#39;);
        
        $vars = get_class_vars(get_class($this));
        foreach ($options as $key=>$value) {
            if (array_key_exists($key, $vars)) {
                $this->$key = $value;
            }
        }
    }
    
    function display()
    {
        echo &#39;<table class="calendar">&#39;;
        $this->showChangeDate();
        $this->showWeeks();
        $this->showDays($this->year,$this->month);
        echo &#39;</table>&#39;;
    }
    
    private function showWeeks()
    {
        echo &#39;<tr>&#39;;
        foreach($this->weeks as $title)
        {
            echo &#39;<th>&#39;.$title.&#39;</th>&#39;;
        }
        echo &#39;</tr>&#39;;
    }
    
    private function showDays($year, $month)
    {
        $firstDay = mktime(0, 0, 0, $month, 1, $year);
        $starDay = date(&#39;w&#39;, $firstDay);
        $days = date(&#39;t&#39;, $firstDay);

        echo &#39;<tr>&#39;;
        for ($i=0; $i<$starDay; $i++) {
            echo &#39;<td> </td>&#39;;
        }
        
        for ($j=1; $j<=$days; $j++) {
            $i++;
            if ($j == date(&#39;d&#39;)) {
                echo &#39;<td class="today">&#39;.$j.&#39;</td>&#39;;
            } else {
                echo &#39;<td>&#39;.$j.&#39;</td>&#39;;
            }
            if ($i % 7 == 0) {
                echo &#39;</tr><tr>&#39;;
            }
        }
        
        echo &#39;</tr>&#39;;
    }
    
    private function showChangeDate()
    {
        
        $url = basename($_SERVER[&#39;PHP_SELF&#39;]);
        
        echo &#39;<tr>&#39;;
	echo &#39;<td><a href="?&#39;.$this->preYearUrl($this->year,$this->month).&#39;">&#39;.&#39;<<&#39;.&#39;</a></td>&#39;;
	echo &#39;<td><a href="?&#39;.$this->preMonthUrl($this->year,$this->month).&#39;">&#39;.&#39;<&#39;.&#39;</a></td>&#39;;
        echo &#39;<td colspan="3"><form>&#39;;
        
        echo &#39;<select name="year" onchange="window.location=\&#39;&#39;.$url.&#39;?year=\&#39;+this.options[selectedIndex].value+\&#39;&month=&#39;.$this->month.&#39;\&#39;">&#39;;
        for($ye=1970; $ye<=2038; $ye++) {
            $selected = ($ye == $this->year) ? &#39;selected&#39; : &#39;&#39;;
            echo &#39;<option &#39;.$selected.&#39; value="&#39;.$ye.&#39;">&#39;.$ye.&#39;</option>&#39;;
        }
        echo &#39;</select>&#39;;
        echo &#39;<select name="month" onchange="window.location=\&#39;&#39;.$url.&#39;?year=&#39;.$this->year.&#39;&month=\&#39;+this.options[selectedIndex].value+\&#39;\&#39;">&#39;;
        

        
        for($mo=1; $mo<=12; $mo++) {
            $selected = ($mo == $this->month) ? &#39;selected&#39; : &#39;&#39;;
            echo &#39;<option &#39;.$selected.&#39; value="&#39;.$mo.&#39;">&#39;.$mo.&#39;</option>&#39;;
        }
        echo &#39;</select>&#39;;        
        echo &#39;</form></td>&#39;;        
	echo &#39;<td><a href="?&#39;.$this->nextMonthUrl($this->year,$this->month).&#39;">&#39;.&#39;>&#39;.&#39;</a></td>&#39;;
	echo &#39;<td><a href="?&#39;.$this->nextYearUrl($this->year,$this->month).&#39;">&#39;.&#39;>>&#39;.&#39;</a></td>&#39;;        
        echo &#39;</tr>&#39;;
    }
    
    private function preYearUrl($year,$month)
    {
        $year = ($this->year <= 1970) ? 1970 : $year - 1 ;
        
        return &#39;year=&#39;.$year.&#39;&month=&#39;.$month;
    }
    
    private function nextYearUrl($year,$month)
    {
        $year = ($year >= 2038)? 2038 : $year + 1;
        
        return &#39;year=&#39;.$year.&#39;&month=&#39;.$month;
    }
    
    private function preMonthUrl($year,$month)
    {
        if ($month == 1) {
            $month = 12;
            $year = ($year <= 1970) ? 1970 : $year - 1 ;
        } else {
            $month--;
        }        
        
        return &#39;year=&#39;.$year.&#39;&month=&#39;.$month;
    }
    
    private function nextMonthUrl($year,$month)
    {
        if ($month == 12) {
            $month = 1;
            $year = ($year >= 2038) ? 2038 : $year + 1;
        }else{
            $month++;
        }
        return &#39;year=&#39;.$year.&#39;&month=&#39;.$month;
    }
    
}

<?php
$params = array();
if (isset($_GET[&#39;year&#39;]) && isset($_GET[&#39;month&#39;])) {
    $params = array(
        &#39;year&#39; => $_GET[&#39;year&#39;],
        &#39;month&#39; => $_GET[&#39;month&#39;],
    );
}
$params[&#39;url&#39;]  = &#39;demo.php&#39;;
require_once &#39;calendar.class.php&#39;;
?>

<html>
    <head>
        <title>日历demo</title>
        <meta http-equiv="Content-Type" content="text/html" charset="UTF-8" />
        <style type="text/css">
            table.calendar {
                border: 1px solid #050;
            }
            .calendar th, .calendar td {
                width:30px;
                text-align:center;
            }            
            .calendar th {
                background-color:#050;
                color:#fff;
            }
            .today{
		color:#fff;
		background-color:#050;                
            }
        </style>
    </head>
    <body>
        <p style="align:center">
            <?php
                $cal = new Calendar($params);
                $cal->display();
            ?>    
        </p>
    </body>
</html>