默默地EEer，原文地址：

http://www.cnblogs.com/hebaichuanyeah/p/5618781.html

在調用linux環境下線程API寫Cpp時，發現異常蛋疼，要么線程函數不能是類的成員函數，要么必須是類的static成員函數（意味著調用的成員變量也必須是static……其實還是不屬于類）。

Qt提供一套線程機制，只要繼承QThread基類并重新實現void run()函數即可。

新建thread.h繼承Qthread，并在thread.cpp中實現它。

thread.h

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#include "QThread"class Thread : public QThread {Q_OBJECT public:Thread();// void setMessage(const Qstring &message);void setRun();void stop();bool getState(); protected:void run(); private:// QString messageStr;volatile bool enable; signals:void OutMessage(QString message); };

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?thread.cpp，在run函數中循環1秒觸發一個信號輸出信息。

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#include "thread.h"Thread::Thread() {enable = true; }void Thread::run() {while(true){if(enable){this->OutMessage(tr("I'm run : thread 1"));msleep(1000);}} } void Thread::stop() {enable = false; } void Thread::setRun() {enable = true; } bool Thread::getState() {return enable; }

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?mainwindow.h，定義一些Qt控件

#ifndef MAINWINDOW_H #define MAINWINDOW_H#include <QMainWindow> #include <QLabel> #include <QGridLayout> #include <QPushButton> #include <QTextEdit> #include <QDoubleValidator> #include <QComboBox> #include <QTranslator>#include "thread.h"#define PI 3.14592653589class MainWindow : public QMainWindow {Q_OBJECT public:MainWindow();~MainWindow(); private:QWidget* mainWindow;QGridLayout * mainLayout;QTextEdit * messageEdit;QPushButton * clearButton;QPushButton * runStopButton;Thread * backThread; private slots:void updateMessage(QString message);void clearMessage();void runStopThread();};#endif

?mainwindow.cpp

#include "mainwindow.h" #include <QPainter>MainWindow :: MainWindow() {mainWindow = new QWidget;this->setCentralWidget(mainWindow);backThread = new Thread();backThread->start();clearButton = new QPushButton(tr("clear"));clearButton->setSizePolicy(QSizePolicy::Fixed,QSizePolicy::Fixed);runStopButton = new QPushButton(tr("stop"));messageEdit = new QTextEdit();messageEdit->setReadOnly(true);mainLayout = new QGridLayout;mainLayout->addWidget(messageEdit,0,0,5,5);mainLayout->addWidget(clearButton,1,5,1,1);mainLayout->addWidget(runStopButton,0,5,1,1);mainWindow->setLayout(mainLayout);QObject::connect(clearButton,SIGNAL(clicked()),this,SLOT(clearMessage()));QObject::connect(runStopButton,SIGNAL(clicked()),this,SLOT(runStopThread()));QObject::connect(backThread,SIGNAL(OutMessage(QString)),this,SLOT(updateMessage(QString)));this->setWindowTitle(tr("thread test~"));this->resize(QSize(300,100));// this->setFixedSize(200,100); }MainWindow :: ~MainWindow() {mainWindow->deleteLater();mainLayout->deleteLater();messageEdit->deleteLater();clearButton->deleteLater();runStopButton->deleteLater(); }void MainWindow::updateMessage(QString message) {messageEdit->append(message); } void MainWindow::clearMessage() {messageEdit->clear(); } void MainWindow::runStopThread() {if(backThread->getState()){backThread->stop();runStopButton->setText(tr("run"));}else{backThread->setRun();runStopButton->setText(tr("stop"));} }

?運行：

后臺線程不斷打印信息，通過run/stop按鈕停止/啟動。

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同時，Qt提供一套線程同步機制

QMutex（互斥鎖），QReadWriteLock（讀寫鎖），QSemaphore（信號量），QWaitCondition（阻塞等待一個條件）。

使用都很簡單，其中QWaitCondition，調用bool wait(QMutex *mutex, unsigned long time = ULONG_MAX)成員函數阻塞。 void wakeOne()和void wakeAll()喚醒一處和所有阻塞。（類似于C#里面的ManualResetEvent 類，.WaitOne() ? .Set()）

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轉載于:https://www.cnblogs.com/hebaichuanyeah/p/5618781.html

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