一個主線程，一個次線程，主線程向次線程發送信號
mythread.h
#include <QThread>
#include <QDebug>
class Mythread : public QThread
{
Q_OBJECT
public:
Mythread();
protected:
void run();
private:
public slots:
void receive_main_signal(int);
};mythread.cpp
#include "mythread.h"
#include <QDebug>
Mythread::Mythread()
{
qDebug()<<"Mythread:" <<QThread::currentThreadId();
//moveToThread(this);}
void Mythread::run()
{
qDebug()<<"run:" <<QThread::currentThreadId();
exec();
}
void Mythread::receive_main_signal(int a)
{
qDebug()<<"from MainWindow:" <<QThread::currentThreadId();
qDebug()<<"i="<<a;
}
MainWindow.h
#include <QMainWindow>
#include "mythread.h"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{Q_OBJECT
public:explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:Ui::MainWindow *ui;
Mythread thread;
signals:void emit_signal_to_thread(int);
public slots:
void start_thread();
};
MainWindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QDebug>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{ui->setupUi(this);
qDebug()<<"MainWindow:" <<QThread::currentThreadId();
connect(this,SIGNAL(emit_signal_to_thread(int)),&thread,SLOT(receive_main_signal(int)));//主線程給次線程發消息
connect(ui->pushButton,SIGNAL(clicked()),this,SLOT(start_thread()));
}
MainWindow::~MainWindow()
{delete ui;
}
void MainWindow::start_thread()
{thread.start();
int i;
for(i=0;i<10;i++)
{emit emit_signal_to_thread(i);
sleep(1);
}}
打印結果：
Mythread: 3063412432 MainWindow: 3063412432 from MainWindow: 3063412432 i= 0 run: 3018308496 from MainWindow: 3063412432 i= 1 from MainWindow: 3063412432 i= 2 from MainWindow: 3063412432 i= 3 from MainWindow: 3063412432 i= 4 from MainWindow: 3063412432 i= 5 from MainWindow: 3063412432 i= 6 from MainWindow: 3063412432 i= 7 from MainWindow: 3063412432 i= 8 from MainWindow: 3063412432 i= 9
結論：主線程向子線程發送信號，子線程對應的槽函數實現還是在主線程中完成的。如何使子線程的槽函數在子線程中完成呢？可以將mythread.cpp中moveToThread(this)的//去掉，最後可以顯示：Mythread: 3064174288 MainWindow: 3064174288
run: 3019070352
from MainWindow: 3019070352
i= 0
from MainWindow: 3019070352
i= 1
from MainWindow: 3019070352
i= 2
from MainWindow: 3019070352
i= 3
from MainWindow: 3019070352
i= 4
from MainWindow: 3019070352
i= 5
from MainWindow: 3019070352
i= 6
from MainWindow: 3019070352
i= 7
from MainWindow: 3019070352
i= 8
from MainWindow: 3019070352
i= 9
可見子線程的槽函數在新線程中運行了，沒有出現在主線程中。但這種方法是被Bradley T. Hughes所唾棄的，所以還是用大家公認爲比較對的方法吧。（見下篇）