检测浏览网站的是否是蜘蛛

实现流程是： 

　　1、判断用户端的浏览器类型

　　2、根据搜索引擎机器人的名称进行判断用户是否蜘蛛人

/**
 * 判断是否为搜索引擎蜘蛛
 *
 * @access  public
 * @return  string
 */
function is_spider($record = true)
{
    static $spider = NULL;

    if ($spider !== NULL)
    {
        return $spider;
    }

    if (empty($_SERVER['HTTP_USER_AGENT']))
    {
        $spider = '';

        return '';
    }

    $searchengine_bot = array(
        'googlebot',
        'mediapartners-google',
        'baiduspider+',
        'msnbot',
        'yodaobot',
        'yahoo! slurp;',
        'yahoo! slurp china;',
        'iaskspider',
        'sogou web spider',
        'sogou push spider'
    );

    $searchengine_name = array(
        'GOOGLE',
        'GOOGLE ADSENSE',
        'BAIDU',
        'MSN',
        'YODAO',
        'YAHOO',
        'Yahoo China',
        'IASK',
        'SOGOU',
        'SOGOU'
    );

    $spider = strtolower($_SERVER['HTTP_USER_AGENT']);

    foreach ($searchengine_bot AS $key => $value)
    {
        if (strpos($spider, $value) !== false)
        {
            $spider = $searchengine_name[$key];

            /*if ($record === true)
            {
                $GLOBALS['db']->autoReplace($GLOBALS['ecs']->table('searchengine'), array('date' => local_date('Y-m-d'), 'searchengine' => $spider, 'count' => 1), array('count' => 1));
            }*/

            return $spider;
        }
    }

    $spider = '';

    return '';
}