QtQt使用回调函数方(callback)

实例代码：

.pro

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++11

# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    main.cpp \
    mainwindow.cpp

HEADERS += \
    mainwindow.h

FORMS += \
    mainwindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

main.cpp

#include "mainwindow.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QDebug>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

typedef QString(*callBack)(QString str);// 函数指针

// ******************调用类********************* //
class CallbackA
{
public:
     void setCallBack(callBack callBackFunc);// 设置回调函数
     callBack m_pCallBackFunc;// 回调函数成员
};

// ******************被调类********************* //
class CallbackB
{
public:
    static QString callBack(QString str);// 声明回调函数
};

// ******************使用类********************* //
class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    CallbackA *oCallbackAo = new CallbackA();
    oCallbackAo->setCallBack(&CallbackB::callBack);// 运行后输出“CallbackB:callBack:  "CallbackA"”
}

MainWindow::~MainWindow()
{
    delete ui;
}


QString CallbackB::callBack(QString str)
{
    qDebug() << "CallbackB:callBack: " << str;
    return "CallbackB:callBack: ";
}

void CallbackA::setCallBack(callBack callBackFunc)
{
    m_pCallBackFunc = callBackFunc;
    m_pCallBackFunc("CallbackA");
}

mainwindow.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>358</width>
    <height>169</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget"/>
 </widget>
 <resources/>
 <connections/>
</ui>