QT QUICK 2 : QML与后端C++组建类MVVM结构工程最小化实现

一、采用QT对方法提供的宏进行结构MVVM的构建

1.打开QT ，并创建QT-QUICK 工程，建议QT5.15及以上

2.准备类 MyObject 其实这个类就可以作为VM使用

myobject.h

#ifndef MYOBJECT_H
#define MYOBJECT_H#include <QObject>class MyObject : public QObject
{Q_OBJECT
public:explicit MyObject(QObject *parent = nullptr);Q_INVOKABLE QString func(QString str);//需要调用的函数//单例static MyObject* getInstance(){static MyObject* myobj = new MyObject() ;return myobj;};int iValue() const;void setIValue(int newIValue);const QString &sString() const;void setSString(const QString &newSString);signals:void iValueChanged();void sStringChanged();private:int m_iValue;		//针对变量 alt+enter 会自动创建一系列相关方法和宏定义QString m_sString="init";//signals://这里的通知动作iValueChanged sStringChanged非常重要，是属性变化后 通知前端做同步的核心Q_PROPERTY(int iValue READ iValue WRITE setIValue NOTIFY iValueChanged)Q_PROPERTY(QString sString READ sString WRITE setSString NOTIFY sStringChanged)
};#endif // MYOBJECT_H

myobject.cpp

#include "myobject.h"
#include <QDebug>MyObject::MyObject(QObject *parent): QObject{parent}
{}//需要调用的函数 
//这里有个重点  必须采用setSString方法来设置sString的值，这样才能启动通知，等号赋值不会通知前端
QString MyObject::func(QString str)
{setSString(sString()+ str + '#' ) ;// m_sString = str+"@";qDebug()<< __FUNCTION__ <<" === "<<str;return sString();
}int MyObject::iValue() const
{return m_iValue;
}void MyObject::setIValue(int newIValue)
{if (m_iValue == newIValue)return;m_iValue = newIValue;emit iValueChanged();
}const QString &MyObject::sString() const
{return m_sString;
}void MyObject::setSString(const QString &newSString)
{if (m_sString == newSString)return;m_sString = newSString;emit sStringChanged();
}

3 main.cpp中连接创建的类

main.cpp 如果版本较新则采用注册单例qmlRegisterSingletonInstance方式进行

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "myobject.h"int main(int argc, char *argv[])
{
#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
#endifQGuiApplication app(argc, argv);QQmlApplicationEngine engine;//关键//qmlRegisterSingletonInstance( "MyObj",1,0,"MyObjectIns",MyObject::getInstance());const QUrl url(QStringLiteral("qrc:/main.qml"));QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,&app, [url](QObject *obj, const QUrl &objUrl) {if (!obj && url == objUrl)QCoreApplication::exit(-1);}, Qt::QueuedConnection);engine.load(url);return app.exec();
}

4 qml部分作为view

main.qml

import QtQuick 2.15
import QtQuick.Window 2.15
import QtQuick.Controls 2.5
import MyObj 1.0Window {width: 640height: 480visible: truetitle: qsTr("Hello World")onWidthChanged: { console.log(width) }//ref动态绑定 由于iValue定义了通知动作；//一个改变 会通知另一个改变  建议用此承接前端属性property string sstring: MyObjectIns.sStringText {id: txttext: sstring}Button {objectName: "myButton"width:100height:100y:100onClicked: {MyObjectIns.func("ee")console.log ( MyObjectIns.sString)console.log (txt.text)console.log (sstring)}}
}