笔记：Qt开发之多线程的实现(QThread、moveToThread)

1，子类化QThread

class WorkerThread : public QThread
{
	Q_OBJECT
	
public:
	explicit MyThread(QObject *parent = nullptr) : QObject(parent), m_isStop(false) {}
	void run() {
		QString result;
		while(!m_isStop) {
			qDebug()<<"child thread"<<QThread::currentThreadId()<<endl;
			/* ... here is the expensive or blocking operation ... */
			emit resultReady(result);
			QThread::sleep(5);  
		}
	}
	void stop(){m_isStop = true;}
	
signals:
  void resultReady(const QString &s);
  
private:
	bool m_isStop;//停止标志位  
};

void MyObject::startWorkInAThread()
{
  WorkerThread *workerThread = new WorkerThread(this);
  connect(workerThread, &WorkerThread::resultReady, this, &MyObject::handleResults);
  connect(workerThread, &WorkerThread::finished, workerThread, &QObject::deleteLater);
  workerThread->start();
}

2，自定义类moveToThread

class Worker : public QObject
{
  Q_OBJECT

public:
    explicit Worker(QObject *parent = nullptr) : QObject(parent), m_isStop(false) {}
	~Worker() { qDebug() << "Worker destroyed in thread" << QThread::currentThreadId(); }
	void stop() { m_isStop = true; }
	
public slots:
  void doWork(const QString &parameter) {
	  QString result;
	  if(!m_isStop) {
		  
		  /* ... here is the expensive or blocking operation ... */
		  emit resultReady(result);		  
	  }
  }

signals:
  void resultReady(const QString &result);
  
private:
    bool m_isStop;
};

class Controller : public QObject
{
  Q_OBJECT
  QThread workerThread;
public:
  Controller() {
	  //不要给对象指定父对象
	  Worker *worker = new Worker;
	  
	  // 将Worker对象移动到新创建的线程中
	  worker->moveToThread(&workerThread);
	  
	  
	  connect(&workerThread, &QThread::finished, worker, &QObject::deleteLater);
	  connect(this, &Controller::operate, worker, &Worker::doWork);
	  connect(worker, &Worker::resultReady, this, &Controller::handleResults);
	  connect(&workerThread, &QThread::started, worker, &Worker::doWork);
	  workerThread.start();// 开启线程
  }
  ~Controller() {
	  workerThread.quit();// 等待线程结束
	  workerThread.wait();
  }
public slots:
  void handleResults(const QString &);
signals:
  void operate(const QString &);
};

bool QObject::connect (const QObject * sender, 
                        const char * signal, 
                        const QObject * receiver,
                        const char * method,
                        Qt::ConnectionType type = Qt::AutoConnection)

Qt::AutoConnection              默认连接
Qt::DirectConnection            槽函数立即调用
Qt::BlockingQueuedConnection    同步调用
Qt::QueuedConnection            异步调用
Qt::UniqueConnection            单一连接

建议使用的方法是在每次循环之前进行一个BOOL值的判断，
当BOOL值为假时，退出循环（当然，也可以使用terminate()粗暴的结束线程）。
当run函数里面没有循环时，函数像普通函数一样，运行完一次即退出函数。
线程结束时会发出信号，此时我们可以通过信号槽来销毁线程：
connect(thread,&QThread::finished
            ,thread,&QObject::deleteLater);//线程结束后调用deleteLater来销毁分配的内存

在new对象时候，直接用this指定其父类（即放入对象数中）
在程序最后自行释放资源   
   connect(this, &list::destroyed, this, [=]() {
        thread->quit();
        thread->wait();
        thread->deleteLater();
        myth->deleteLater();
        bub->deleteLater();
        });

qDebug()<<objectName()<<":"<<"getstarted() , tid :"<<QThread::currentThreadId();

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