这是我写的一段代码，里面通过PHP异常功能，实现报错时显示出错代码所在行。当使用者操作出错时，截图给我，我可以很快得去追踪和排查错误！

public function added_business_submit(){    try{        extract($_POST);        if(''==$title)          self::json(0,sprintf(ERROR_EMPTY,'工单标题'));        if(''==$is_trusteeship) self::json(0,sprintf(ERROR_EMPTY,'服务器类别'));        if(''==$eqroom_id)      self::json(0,sprintf(ERROR_EMPTY,'所在机房'));                M()->startTrans();        $com_info     = M('company')->where(array('com_qyuserid'=>$com_qyuserid))->find();        $com_id       = $com_info['com_id'];        $com_name     = $com_info['com_name'];            if(empty($com_info)) throw new Exception(ERROR_NOTFOUND_USER);                $data = array(            'com_id'       => $com_id,            'com_name'     => $com_name,            'type'         => 1,            'step'         => 1,            'poster'       => self::$user['name'],            'posttime'     => self::$datetime,            'eqroom_name'  => D('EquipRoom')->get_eqroom_name($eqroom_id),        );        $data = array_merge($data,$_POST);        $agent_id = M('working_agent')->add($data);        if(false===$agent_id) throw new Exception(ERROR_SUBMIT);                $result = D('StepLogAgent')->next_step($agent_id,$remark);        if(false===$result) throw new Exception(ERROR_SUBMIT);    }catch(Exception $e){        M()->rollback();        $this->exception_handle($e);    }    M()->commit();    self::json(1,SUCCESS_SUBMIT);}private function exception_handle(Exception $e){    $msg  = $e->getMessage();    $line = $e->getLine();    //**/print_r($e); echo M()->getLastSql();    $name = self::$user['name'];    $time = self::$datetime;    $sql  = M()->getLastSql();    $log  = $time." ".$name.":{
   $msg}({
   $line}) {
   $sql}";    self::mylog($log,'Agent');    self::json(0,"{
   $msg}({
   $line})");}