Qt使用Q_DECLARE_INTERFACE Q_INTERFACES宏实现接口类使用qobject_cast进行类型转换

teacher伟大光荣且正确2024-03-12 19:16

在写抽象类或者接口的时候，肯定是不能继承QObject的

但是又想使用qobject_cast进行类型转换，使用以下办法就能实现

cpp 复制代码

#ifndef FACTORYINTERFACE_H__
#define FACTORYINTERFACE_H__
#include <QObject>
class FactoryInterface{
public:
	FactoryInterface() {};
	virtual ~FactoryInterface() {};

};

QT_BEGIN_NAMESPACE
Q_DECLARE_INTERFACE(FactoryInterface, "DetectionSoftware.Factory.FactoryInterface")//一定是唯一的标识符
QT_END_NAMESPACE

#endif // FACTORYINTERFACE_H__

cpp 复制代码

/*
* 这个抽象类继承自FactoryInterface抽象类
* 
*/

#ifndef FACTORYINTERFACE1_0_H__
#define FACTORYINTERFACE1_0_H__
#include "FactoryInterface.h"

class FactoryInterface1_0: public  FactoryInterface{
public:
	FactoryInterface1_0() {};
	virtual ~FactoryInterface1_0() {};

signals:


public slots:


};

QT_BEGIN_NAMESPACE
Q_DECLARE_INTERFACE(FactoryInterface1_0, "DetectionSoftware.Factory.FactoryInterface1_0")//一定是唯一的标识符
QT_END_NAMESPACE
#endif // FACTORYINTERFACE1_0_H__

cpp 复制代码

#ifndef FACTORYIMPLEMENT1_0_H__
#define FACTORYIMPLEMENT1_0_H__

#include <QObject>
#include "factoryInterface1_0.h"
class FactoryImplement1_0  : public QObject, public FactoryInterface1_0{
	Q_OBJECT
		Q_INTERFACES(FactoryInterface FactoryInterface1_0)

public:
	FactoryImplement1_0(QObject *parent = nullptr);
	~FactoryImplement1_0();
};


#endif // FACTORYIMPLEMENT1_0_H__

直接看代码，重点就是

Q_INTERFACES(FactoryInterface FactoryInterface1_0)

Q_DECLARE_INTERFACE(FactoryInterface1_0, "DetectionSoftware.Factory.FactoryInterface1_0")//一定是唯一的标识符

这两个宏，具体作用不赘述。

然后使用

cpp 复制代码

	QObject* test = new FactoryImplement1_0();
	FactoryInterface* t = qobject_cast<FactoryInterface*>(test);
	FactoryInterface1_0* tt = qobject_cast<FactoryInterface1_0*>(test);

注意

要想qobject_cast能用，实现类必须使用Q_INTERFACES指定转换的抽象类

只能从QObject类型转为Q_INTERFACES宏指定的抽象类