根据年或年月获取起止时间

public function getDateRange($year, $month = 0)
{
    if(empty($month)){
        $time['begin'] = date('Y-m-d H:i:s', mktime(0,0,0,1,1,$year));
        $time['end'] = date('Y-m-d H:i:s', mktime(23,59,59,12,31,$year));
    }else{
        $time['begin'] = date('Y-m-d H:i:s', mktime(0,0,0,$month,1,$year));
        $time['end'] = date('Y-m-d H:i:s',mktime(23,59,59,($month+1),0,$year));
    }
    return $time;
}