Qt开发：释放线程中创建的QUdpSocket对象

在做Symbian应用开发和MeeGo应用开发时Q框架是一个统一的开发框架，很多时候需要在QThread的run中new一个QUdpSocket来收发数据.这时,这个socket对象的释放就成了一个麻烦的问题.

51CTO编者按：在做Symbian应用开发和MeeGo应用开发时Q框架是一个统一的开发框架，很多时候需要在QThread的run中new一个QUdpSocket来收发数据.这时,这个socket对象的释放就成了一个麻烦的问题.

如果在thread的析构中直接delete这个socket对象,则会出现如下异常:

QSocketNotifier: socket notifiers cannot be disabled from another thread
ASSERT failure in QCoreApplication::sendEvent: “Cannot send events to objects owned by a different thread. Current thread 560cb8. Receiver ” (of type ‘QNativeSocketEngine’) was created in thread a617748〃, file kernel\qcoreapplication.cpp, line 349
Invalid parameter passed to C runtime function.
Invalid parameter passed to C runtime function.

以下是解决方案:

◆在线程中定义一个线程释放的标识

◆在run()中用while来判断这个标识,以便于结束socket对象.

◆在thread的析构中,设定标识,并使用quit()和wait().

代码如下:

UdpSocketThread::UdpSocketThread(QObject *parent) :
QThread(parent)
{
this->socket = 0;
this->needStop = false;
}

UdpSocketThread::~UdpSocketThread()
{
this->needStop = true;
quit();
wait();
}

void UdpSocketThread::run()
{
socket = new QUdpSocket;
connect(socket,SIGNAL(readyRead()),this,SLOT(readPendingDatagrams()));
socket->bind(2234);
exec();
while(this->needStop)
{
if(this->socket)
{
delete this->socket;
this->socket = 0;
}
break;
}
}

这个线程对象的释放比较有代表性,应该可以解决很多类似的问题.

另外,方法可能还有其他的,这里只是举了一种而已.

其实,问题的关键就是:线程中创建的对象就必须在线程中释放.

PS:

经shiroki的指正,其实QT有更好的机制来释放对象.那就是deleteLater(). 于是,事情就显得非常简单,请看代码:

UdpSocketThread::UdpSocketThread(QObject *parent) :

QThread(parent)
{
socket = 0;
}

UdpSocketThread::~UdpSocketThread()
{
this->socket->deleteLater();
quit();
wait();
}

void UdpSocketThread::run()
{
socket = new QUdpSocket;
connect(socket,SIGNAL(readyRead()),this,SLOT(readPendingDatagrams()));
socket->bind(2234);
exec();

}