php      部分

public  function get_comment(){
   $post_id  = I(‘get.post_id‘,0,‘intval‘);
   $table    = I(‘get.table‘);
   $msg    = I(‘get.msg‘);
   $comment_model=D("Common/Comments");
   $comments=$comment_model->where(array("post_table"=>$table,"post_id"=>$post_id,"status"=>1,‘user_type‘=>2))->order("createtime ASC")->select();

   $OldCommentData = http://www.mamicode.com/count($comments);

       if($msg==‘init‘){
           if(!empty($comments)){

      $comments =self::forData($comments);
           }
      echo json_encode($comments);exit;
   }
   $time_count =0;
   while(true){
      set_time_limit(0);
      $time_count++;
      $newComments=$comment_model->where(array("post_table"=>$table,"post_id"=>$post_id,"status"=>1,‘user_type‘=>2))->order("createtime ASC")->select();

      $newCommentData = http://www.mamicode.com/count($newComments);
      if($newCommentData != $OldCommentData){
         if(!empty($comments)){

            $newComments =self::forData($newComments);
            echo json_encode($newComments);
            break;
         }

      }
      usleep(1000);
      //一定的时间后没有数据变化也跳出
      if($time_count >= 800){
         $datahttp://www.mamicode.com/= "";
         echo json_encode($data);
         break;
      }
   }

}

ajax 轮询 和 php长连接