WeChatがPHPで投稿データを受信できない場合の対処方法

public function getIndex(){
        if (ob_get_contents())  ob_end_clean();
        $postStr = isset($GLOBALS["HTTP_RAW_POST_DATA"])?$GLOBALS["HTTP_RAW_POST_DATA"]:'';//获取post过来的数据
        if (!empty($postStr)){
            $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
            $this->postObj = $postObj;
            $this->fromUserName = $postObj->FromUserName;//发送方
            $this->toUserName = $postObj->ToUserName;//接收方（即本公众账号）
            $this->msgType = trim($postObj->MsgType);//消息类型
            $this->content = trim($postObj->Content);
            $this->event = trim($postObj->Event);
            $this->eventKey = trim($postObj->EventKey);
            $this->dealMsg();
        }else{
            $this->wx->makeInfo(Input::all());
            $this->wx->valid();//非消息推送时，默认为校验
        }
        flush();
    }