QThread定时器

如何在子线程中启动定时器：

MyThread::MyThread(QObject *parent)
	: QThread(parent)
{
	printf("[%d] construct\n",this->currentThreadId());
}

MyThread::~MyThread()
{
	delete timer;
}

void MyThread::timedone()
{
	printf("[%d] test...\n",this->currentThreadId());
}

void MyThread::run()
{
	printf("[%d] sub thread start\n",this->currentThreadId());

	timer = new QTimer();
	connect(timer,SIGNAL(timeout()),this,SLOT(timedone()),Qt::DirectConnection);
	timer->start(2000);

	exec();
}

如上：在线程run中创建QTimer，使用DirectConnection连接槽函数，然后启动qt消息循环exec，输出如下： 

[5980] main thread start
[5980] construct
[5516] sub thread start
[5516] test...
[5516] test...
[5516] test...
[5516] test...
[5516] test...
[5516] test...
[5516] test...

1.如果QTimer传入this指针，输入如下： 

[7616] main thread start
[7616] construct
[7380] sub thread start
QObject: Cannot create children for a parent that is in a different thread.
(Parent is MyThread(0xe2b010), parent's thread is QThread(0x7debf8), current thr
ead is MyThread(0xe2b010)
[7380] test...
[7380] test...
[7380] test...

虽然也能正常运行，但会提示一个警告(算是)：cannot create child for a parent，不能为一个父对象创建一个子对象在不同的线程，应该是创建了，但没有关联上父对象而已(所以应该在析构函数中delete)，对么。 

2.将DirectConnection去掉，输出如下：

[4036] main thread start
[4036] construct
[7580] sub thread start
[4036] test...
[4036] test...
[4036] test...
[4036] test...
[4036] test...

输出还在主线程中 

3.将exec换成其他比如while(1)，信号槽能正常连接，但永远不会调用超时函数timedone，信号其实是消息，走qt消息循环吧

[6020] main thread start
[6020] construct
[1244] sub thread start

from: http://www.voidcn.com/article/p-kwkawruy-xd.html