Qt多線程 信號(hào)和槽以及C++11的綁定 及QMetaObject::invokeMethod
用C++11綁定信號(hào)和槽,能使代碼可讀性更高,靈活性更強(qiáng)
注:connect()中可聲明連接類型,默認(rèn)缺省為AutoConnection
點(diǎn)擊滾動(dòng)到 “連接類型” 介紹↓
:
#include#includeclass?MyWindow?:?public?QWidget
{
????Q_OBJECT
public:
????typedef??std::functionfuc1;
????MyWindow(QWidget?*parent?=?0);
????~MyWindow();
????QPushButton?*??btn;
????QLabel*?label;??QVBoxLayout*?Vbox;?
????QGridLayout*?grid;
????void?click2(bool?checked);
????void?set(QString?s);
public?slots:
????void?On_TestBtn_Cliked();
????void?set2(QString?s);
};MyWindow::MyWindow(QWidget?*parent)
????:?QWidget(parent)
{
????label?=?new?QLabel(QStringLiteral("你好"));?
????btn??=?new?QPushButton("Test");?
????grid?=?new?QGridLayout();?
????grid->addWidget(btn,0,0);
????Vbox?=?new?QVBoxLayout();
????Vbox->addLayout(grid);
????Vbox->addWidget(label);
????setLayout(Vbox);
????fuc1?fu?=?std::bind(&MyWindow::click2,?this,?std::placeholders::_1);
????connect(btn,?&QPushButton::clicked,?this,?fu);
}
MyWindow::~MyWindow()
{
}
void?MyWindow::set(QString?s)
{
????qDebug()?<<"set:"<<?QThread::currentThreadId();
????label->setText(s);
}
void?MyWindow::set2(QString?s)
{
????qDebug()?<<?"set:"?<<?QThread::currentThreadId();
????label->setText(s);
}
void?MyWindow::click2(bool?checked)
{
????qDebug()?<<?"clcik2:"<start();
}
void?MyWindow::On_TestBtn_Cliked()
{
????qDebug()?<<?"click";
}線程:
#pragma?once
#include#includeclass?MyThread?:
????public?QThread
{
????Q_OBJECT
public:
????QObject*??window;
????void?run();
????MyThread(QObject*?parent=NULL);
????~MyThread();
signals:
????void??print(QString);
};#include?"MyThread.h"
#include?"MainWindow.h"
MyThread::MyThread(QObject*?parent):QThread(parent)
{
????window?=?parent;
????MyWindow*??w?=?(MyWindow*)parent;?
?std::functionfu?=?std::bind(&MyWindow::set,?w,?std::placeholders::_1);
????connect(this,?&MyThread::print,?w,fu);?
}
MyThread::~MyThread()
{
}
void??MyThread::run()
{
????qDebug()?<<?"Thread?Begin";
????int?cout?=?0;
????while?(true)
????{
????????qDebug()?<<?"MyThread::run:"?<<?QThread::currentThreadId();
????????emit?print(QString::number(cout));
????????Sleep(1);
????????cout++;
????}
}可以看到,print綁定的線程id和主線程相同,為線程安全
????connect(this,?&MyThread::print,?w,?[=](QString?s)?{
????????w->set(s);
????????qDebug()?<<?"connet?fuc:"?<<?s?<<?"?"?<<?QThread::currentThreadId();
????????//此時(shí)?線程id為主線程,可隨意調(diào)用主線程對(duì)象的界面操作
????});void??MyThread::run()
{
????qDebug()?<<?"Thread?Begin";
????int?cout?=?0;
????while?(true)
????{
????????qDebug()?<<?"MyThread::run:"?<<?QThread::currentThreadId();
??????QMetaObject::invokeMethod(w,?"set2",?Q_ARG(QString,?QString::number(cout)));
????????Sleep(1);
????????cout++;
????}
}MyThread::MyThread(QObject*?parent):QThread(parent)
{
????window?=?parent;
????MyWindow*??w?=?(MyWindow*)parent;
????connect(this,?&MyThread::print,?w,?std::bind(&QLabel::setText,?w->label?,?std::placeholders::_1));
}connect(this,?&MyThread::print,?w->label,?[=](QString?s)
????{
????????//if(s.indexOf(xxxxx))?此處可以對(duì)字符串進(jìn)行過濾
????????qDebug()?<<?"Bind?Fuc:"?<<?QThread::currentThreadId();
????????w->label->setText(s);
????});或者
????connect(this,?&MyThread::print,?w,?[=](QString?s)
????{
????????//if(s.indexOf(xxxxx))?此處可以對(duì)字符串進(jìn)行過濾
????????qDebug()?<<?"Bind?Fuc:"?<<?QThread::currentThreadId();
????????w->label->setText(s);
????});QMetaObject::invokeMethod
修改界面中的槽set2為：
void?MyWindow::set2(QString?s,?int?pid)
{
????if?(pid?==(int)QThread::currentThreadId())
????{
????????qDebug()?<<?QStringLiteral("?此類型的線程不在主線程中::"?)<<?s;
????????qDebug()?<<?"id_1:"?<<?pid?<<?"?id_2:"?<<?QThread::currentThreadId();
????}
}線程:
void??MyThread::run()
{
????qDebug()?<<?"Thread?Begin";
????int?cout?=?0;
????int?_pid;
????while?(true)
????{
????????_pid?=?(int)QThread::currentThreadId();
????????qDebug()?<<?"MyThread::run:"?<<?_pid;
???????//?emit?print(QString::number(cout));
????????MyWindow*??w?=?(MyWindow*)window;
????????QMetaObject::invokeMethod(w,?"set2",?Qt::ConnectionType::QueuedConnection,
????????????Q_ARG(QString,?"QueuedConnection"),?Q_ARG(int,?_pid)
????????);
????????QMetaObject::invokeMethod(w,?"set2",?Qt::ConnectionType::AutoConnection,
????????????Q_ARG(QString,"AutoConnection"),?Q_ARG(int,?_pid)
????????);
????????QMetaObject::invokeMethod(w,?"set2",?Qt::ConnectionType::BlockingQueuedConnection,?
????????????Q_ARG(QString,?"BlockingQueuedConnection"),Q_ARG(int,?_pid)
????????);
????????QMetaObject::invokeMethod(w,?"set2",?Qt::ConnectionType::DirectConnection,
????????????Q_ARG(QString,?"DirectConnection"),?Q_ARG(int,?_pid)
????????);
????????QMetaObject::invokeMethod(w,?"set2",?Qt::ConnectionType::UniqueConnection,?
????????????Q_ARG(QString,?"UniqueConnection"),?Q_ARG(int,?_pid)
????????);
????????Sleep(1);
????????cout++;
????}
}可見,DirectConnection連接類型的線程ID與主線程不同,與線程相同,不是線程安全,其他連接類型暫時(shí)無法找到方法測(cè)試,有例子的朋友可以跟我交流下,謝謝
是官方說明的連接類型,翻譯
說明:信號(hào):發(fā)送者 ?槽:接受者 ?信號(hào)和槽所在的線程是創(chuàng)建他們的線程,而不是調(diào)用connnet的時(shí)候所在的線程 AutoConnection
如果接收方住在線程發(fā)出信號(hào),使用Qt::DirectConnection。否則,使用Qt::QueuedConnection。連接類型發(fā)送信號(hào)時(shí)決定。
解釋:
如果接收方住在線程發(fā)出信號(hào),使用Qt::DirectConnection。否則,使用Qt::QueuedConnection。連接類型發(fā)送信號(hào)時(shí)決定。
也就是說,自動(dòng)判斷,如果信號(hào)和槽在同一個(gè)線程,就調(diào)用Qt::DirectConnection，否則調(diào)用Qt::QueuedConnection
DirectConnection
調(diào)用插槽立即發(fā)出信號(hào)時(shí)。槽是在信號(hào)線程中執(zhí)行的。
QueuedConnection
可以理解為異步?
當(dāng)槽發(fā)送給調(diào)用接收事件循環(huán)的線程時(shí),槽在接收者的線程中執(zhí)行。
也就是說,此連接類型,只管把信號(hào)發(fā)送到槽所在的線程事件中,不會(huì)等待槽所在的線程事件處理完畢
,槽所在線程事件循環(huán)當(dāng)處理到此信號(hào)時(shí),才會(huì)執(zhí)行相應(yīng)操作
BlockingQueuedConnection
可以理解為同步,阻塞當(dāng)前線程直到同步?
當(dāng)槽發(fā)送給調(diào)用接收事件循環(huán)的線程時(shí),槽在接收者的線程中執(zhí)行。
也就是說,此連接類型,不但把信號(hào)發(fā)送到槽所在的線程事件中,而且會(huì)等待槽所在的線程事件處理完畢
,槽所在線程事件循環(huán)當(dāng)處理到此信號(hào)時(shí),才會(huì)執(zhí)行相應(yīng)操作,信號(hào)所在的線程才會(huì)繼續(xù)下一行代碼
UniqueConnection
資料太少,不知道此類型的大概用途。。。
這是一個(gè)標(biāo)志,可以結(jié)合上述任何一個(gè)連接類型,使用逐位或。當(dāng)Qt:UniqueConnection,QObject:connect()將會(huì)失敗如果連接已經(jīng)存在(即如果相同的信號(hào)已經(jīng)連接到同一個(gè)槽同一雙對(duì)象)。這個(gè)標(biāo)志是在Qt 4.6中引入的。
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