功能：ThinkPHP5.1 搜索功能时 关键字标红
错误：输入时，Malformed UTF-8 characters, possibly incorrectly encoded
首先判断一下关键字是否存在并且不能为空在查询
if(isset($keywords) && !empty($keywords)){
foreach($result as $key=>$val){
$result[$key]['title'] = preg_replace("/({$keywords})/i","<b style='color:red'>{$keywords}</b>",$val['title']);
}
}