[讨论]关于TcpSocket 状态检测 [复制链接]

在QTCPSOCKET类中
有<TD topAlign? rightAlign>void<TD bottomAlign?>stateChanged ( QAbstractSocket::SocketState socketState )这样一个信号，当socket状态改变比如（服务器断开），客户端能根据这样一个信号作出相应的处理。
下面是状态的枚举项

QAbstractSocket::UnconnectedState[/td]<TD topAlign?>0[td]The socket is not connected.

QAbstractSocket::HostLookupState[/td]<TD topAlign?>1[td]The socket is performing a host name lookup.

QAbstractSocket::ConnectingState[/td]<TD topAlign?>2[td]The socket has started establishing a connection.

QAbstractSocket::ConnectedState[/td]<TD topAlign?>3[td]A connection is established.

QAbstractSocket::BoundState[/td]<TD topAlign?>4[td]The socket is bound to an address and port (for servers).

QAbstractSocket::ClosingState[/td]<TD topAlign?>6[td]The socket is about to close (data may still be waiting to be written).

QAbstractSocket::ListeningState[/td]<TD topAlign?>5[td]For internal use only.

我想知道的是：Qt 他是如何检测套接字的状态的，从而发送这个信号。
求教........