[英]Passing QString to QThread through Signal/Slot mechanism
我无法让MainWindow与Worker线程进行通信。 我正在使用通常的SIGNAL / SLOT机制传递QString对象。 我的程序应该将QString“ Alice”从MainWindow传输到在QThread中处理的类Worker的worker对象,然后再次返回。 使用我的MacBook Pro上的Qt 4.8和Clang,代码可以毫无错误地编译并且可以顺利运行。 这是显示我的问题的最少代码。
主窗口
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <worker.h>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
void ThreadedWork();
~MainWindow();
private:
Ui::MainWindow *ui;
QString name;
private slots:
void errorString(QString);
public slots:
void getFromWorker(QString);
signals:
void sendToWorker(QString);
};
#endif // MAINWINDOW_H
主窗口
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QThread>
#include <QDebug>
MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow)
{
ui->setupUi(this);
name = "Alice";
qDebug() << "The name in MainWindow is: " << name << " from ThreadID = " << QThread::currentThreadId();
ThreadedWork();
qDebug() << "Name sent from the Worker Thread is: " << name;
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::errorString(QString string)
{
qDebug() << "The error from the threaded process is: " << string;
}
void MainWindow::ThreadedWork()
{
Worker* worker = new Worker;
emit sendToWorker(name);
connect(this,SIGNAL(sendToWorker(QString)),worker,SLOT(getFromMain(QString)));
connect(worker,SIGNAL(sendToMain(QString)),this,SLOT(getFromWorker(QString)));
QThread *thread = new QThread;
worker->moveToThread(thread);
connect(worker, SIGNAL(error(QString)), this, SLOT(errorString(QString)));
connect(thread, SIGNAL(started()), worker, SLOT(process()));
connect(worker, SIGNAL(finished()), thread, SLOT(quit()));
connect(worker, SIGNAL(finished()), worker, SLOT(deleteLater()));
connect(thread, SIGNAL(finished()), thread, SLOT(deleteLater()));
thread->start();
}
void MainWindow::getFromWorker(QString someName) //slot implementation
{
name = someName;
}
工人
#ifndef WORKER_H
#define WORKER_H
#include <QObject>
class Worker : public QObject
{
Q_OBJECT
public:
explicit Worker(Worker * parent = 0);
~Worker();
signals:
void sendToMain(QString);
void error(QString err);
void finished();
public slots:
void getFromMain(QString);
void process();
private:
QString name;
};
#endif // WORKER_H
worker.cpp
#include "worker.h"
#include <QDebug>
#include <QThread>
Worker::Worker(Worker * parent)
{
}
Worker::~Worker()
{
}
void Worker::process() {
// allocate resources using new here
qDebug() << "name recieved from Main is: " << name;
qDebug() << "name passed to Worker Thread is: " << name << " having ThreadID = " << QThread::currentThreadId();
emit sendToMain(name);
emit finished();
}
void Worker::getFromMain(QString someName) // slot implementation
{
name = someName;
}
我的输出是:
The name in MainWindow is: "Alice" from ThreadID = 0x7fff7de7a300
Name sent from the Worker Thread is: "Alice"
name recieved from Main is: ""
name passed to Worker Thread is: "" having ThreadID = 0x1107a9000
如上所示,我无法将QString“ Alice”传递给工作人员。 我在这里想念什么?
您的ThreadedWork()
方法中的问题:
您首先发出信号, emit sendToWorker(name);
并且只有他们将这个连接到插槽-这是您失败的根源。
像这样更改行:
void MainWindow::ThreadedWork()
{
Worker* worker = new Worker;
connect(this,SIGNAL(sendToWorker(QString)),worker,SLOT(getFromMain(QString)));
connect(worker,SIGNAL(sendToMain(QString)),this,SLOT(getFromWorker(QString)));
emit sendToWorker(name);
QThread *thread = new QThread;
worker->moveToThread(thread);
...
}
我可能会得到预期的结果:
The name in MainWindow is: "Alice" from ThreadID = 0xcbc
Name sent from the Worker Thread is: "Alice"
name recieved from Main is: "Alice"
name passed to Worker Thread is: "Alice" having ThreadID = 0xff8
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.