QTcpSocket的connected

客户端程序，点击按钮调用slotEnter，连接服务器：

void TcpClient::slotEnter()                    
{        
 if(!status)
 {
  QString ip=LineEditServerIP->text();
  if(!serverIP->setAddress(ip))
  {
   QMessageBox::information(this,tr("error"),tr("server ip address error!"));
   return;
  }
  if(LineEditUser->text()=="")
  {
   QMessageBox::information(this,tr("error"),tr("User name error!"));
   return ;
  } 
  userName=LineEditUser->text();
 
  //tcpSocket = new QTcpSocket(this);//在这里new就没有问题
  connect(tcpSocket,SIGNAL(connected()),this,SLOT(slotConnected()));
  connect(tcpSocket,SIGNAL(disconnected()),this,SLOT(slotDisconnected()));
  connect(tcpSocket, SIGNAL(readyRead()),this, SLOT(dataReceived()));
  
  tcpSocket->connectToHost ( *serverIP, port);
  
  status=true;
 }
 else
 {
  int length = 0;
  
  QString msg=userName+tr(":Leave Chat Room");
     if((length=tcpSocket->write(msg.toLatin1(),msg.length()))!=msg.length())
     {
      return ;
     }   
  tcpSocket->disconnectFromHost();
  
  status=false;
 }
 
}

 

void TcpClient::slotConnected()                    
{
 int length = 0;
 PushButtonSend->setEnabled( true );
 PushButtonEnter->setText(tr("Leave"));
 
 QString msg=userName+tr(":Enter Chat Room");
    if((length=tcpSocket->write(msg.toLatin1(),msg.length()))!=msg.length())
    {
     return ;
    } 
}

void TcpClient::slotDisconnected()                    
{
 PushButtonSend->setEnabled( false );
 PushButtonEnter->setText(tr("Enter"));
}

 

 

本来这样考虑，每次点击，连接服务器都要new QTcpSocket似乎不太好，就在TcpClient构造函数事先new好，后面调用connectToHost和 disconnectFromHost即可。但是经测试，如果这样做，slotConnected()会调用两次，也就是说connected()信号会发射两次。（什么原因？）三个connect要放到构造函数中去

忘记信号和槽还连着：

  connect(tcpSocket,SIGNAL(connected()),this,SLOT(slotConnected()));
  connect(tcpSocket,SIGNAL(disconnected()),this,SLOT(slotDisconnected()));
  connect(tcpSocket, SIGNAL(readyRead()),this, SLOT(dataReceived()));