设备未打开错误 + QIODevice::write

Question

我收到错误：

QIODevice::write (QTcpSocket): device not open. After trying , I think problem is passing parameter server->nextPendingConnection() into object. Can someone has idea how to do it correctly?

我的理解是 socketClient 的对象未正确初始化。我在 Qt 中使用 Ubuntu。

我正在使用 Qt 实现服务器。服务器部分有两个类基于 QTcpServer 和 QTcpSocket。说 Server 和 SocketClient。我正在服务器中创建 SocketClient 对象，出于测试目的，我打开了 telnet 会话并希望看到该服务器在终端上写入 "hello"。但不知何故它不起作用。谁能告诉我哪里出错了。

Server::Server(QObject *parent) : QObject(parent)
{
  server_obj = new QTcpServer( this ); 
}

void Server::startServer()
{
  connect( server_obj, SIGNAL( newConnection() ), this, SLOT( incomingConnection() ) );
  if( !server_obj->listen( QHostAddress::Any, 9999) )
  {
    qDebug() << " Server failed to get started";
  }
  else
  {
   qDebug() << " Server started"; // this is successful
  }
}


void Server::incomingConnection()
{
  socketforClient = new SockClient( server_obj->nextPendingConnection() );// has a doubt on nextPendingconection??

  //only for testing remove it
  socketforClient->writeToClient();
}

Class 客户

 * Description: Its a constructor.I have changed default constructor to add QTcpSocket* object in parameter.I used this constructor in  void Server::incomingConnection()
 */
SockClient::SockClient(QObject *parent,QTcpSocket* socket ) : QObject(parent)
{
  socketClient = new QTcpSocket( socket );

 qDebug() << " we are in constructor of 1st sockclient ";

}



// this is for testing purpose only

void SockClient::writeToClient()
{
   socketClient->write(" hello world\r\n");
   socketClient->flush();
   socketClient->waitForBytesWritten(3000);

}

//SockClient的头文件

class SockClient : public QObject
{
  Q_OBJECT
public:

 explicit  SockClient( QObject *parent, QTcpSocket* socket= 0 ); // I have created
    void writeToClient(); // This is for testing purpose
 ~SockClient();
signals:

private slots:
  void readClient();

private:
  void sendResponsetoMops();

  QTcpSocket *socketClient;

  quint16 nextBlockSize;

public slots:
};

Answer 1

您使用：

socketClient = new QTcpSocket( socket );

尝试使用以下代码：

socketClient = socket;

并使用 socketforClient = new SockClient(this, server->nextPendingConnection() );

而不是

 socketforClient = new SockClient( server->nextPendingConnection() );

设备未打开错误 + QIODevice::write

device not open error + QIODevice::write

c++

qt

client-server

tcp-ip