C++：2.工厂模式

工厂模式主要解决，同一类接口，不同厂家有不同实现这类问题。

以业务集成相机sdk为例，相机常用到的功能有打开相机、读取流、关闭流、设置相机参数等。但不同厂家sdk实现方式不一样，如果不用工厂模式，那相同的业务代码，可能要写很多份。使用后，整体代码变得简洁，耦合性好。下面举例说明。

1.抽象相机基类

基类中通常包含两类接口，一类是通用接口，这类接口和相机厂家无关，但相机创建时候又都会用到。另一类是纯虚函数接口，这类接口就是相机相关操作的抽象，如打开相机等。

基类头文件

cpp 复制代码

#ifndef _ICAMERA_H_
#define _ICAMERA_H_

#include <string>
#include <map>

class ICamera
{
public:
	ICamera(std::string cameraName) :name(cameraName) {};

	/**
	 * @brief 加载本地图片，仿真使用
	 * @param cameraName
	 * @param simPicDir
	*/
	ICamera(std::string cameraName, std::string picDir);

	virtual ~ICamera() = default;

	/*************************相机厂家重写*************************/

	/**
	 * @brief 相机初始化
	 * @return
	*/
	virtual void init(CameraManagePara cmPara) = 0;

	/**
	 * @brief 设置相机参数
	 * @param para
	 * @return
	*/
	virtual bool setParameter(CameraThreadPara para) = 0;

	/**
	 * @brief 相机在线状态
	 * @return
	*/
	virtual bool isOnline() = 0;

	/**
	 * @brief 句柄是否有效
	 * @return
	*/
	virtual bool isValidHandle() = 0;

	/**
	 * @brief 关闭相机
	*/
	virtual void close() = 0;

	/**
	 * @brief 关闭流
	 * @param
	*/
	virtual void stopGrab() = 0;


	/*************************基类通用接口-厂家不需要实现*************************/


	/**
	 * @brief 获取相机名称
	 * @return
	*/
	std::string getCameraName();
	
	/**
	 * @brief 可以抽取出来的通用逻辑
	 * @return
	*/
	void commonFun(std::string picDir);


public:

	/**
	 * @brief 通用成员变量
	*/
	uint64_t frameTime = 0;
	uint64_t frameId = 0;
	
	/**
	 * @brief 相机名称
	*/
	std::string name;


};

#endif // !_ICAMERA_H_

基类源文件

cpp 复制代码

#include "ICamera.h"

ICamera::ICamera(std::string cameraName, std::string picDir)
{
	name = cameraName;
	commonFun(picDir);
}


std::string ICamera::getCameraName()
{
	return name;
}

void ICamera::commonFun(std::string picDir)
{
	//业务逻辑

}

2.具体相机子类

这里只举例一个厂家，如果多个厂家，写多个子类就行。

头文件

cpp 复制代码

#ifndef _DSCAMERA_H_
#define _DSCAMERA_H_

#include "ICamera.h"
#include "DVPCamera.h"

class DSCamera : public ICamera
{
public:
	~DSCamera() override { close(); }
	DSCamera(std::string cameraName, std::string simPicDir)
		: ICamera(cameraName, simPicDir) {}

	/**
	 * @brief 相机初始化
	 * @return
	*/
	virtual void init(CameraManagePara cmPara) override;

	/**
	 * @brief 设置相机参数
	 * @param para
	 * @return
	*/
	virtual bool setParameter(CameraThreadPara para) override;

	/**
	 * @brief 相机在线状态
	 * @return
	*/
	virtual bool isOnline() override;

	/**
	 * @brief 句柄是否有效
	 * @return
	*/
	virtual bool isValidHandle() override;

	/**
	 * @brief 关闭相机
	*/
	virtual void close() override;

	/**
	 * @brief 关闭流
	 * @param
	*/
	virtual void stopGrab() override;


private:
	//bool isValidHandle();
	void connect(CameraManagePara cmPara);

	//相机原生句柄
	dvpHandle handle;

};


#endif // !_DSCAMERA_H_

源文件

cpp 复制代码

#include "DSCamera.h"

dvpInt32 dSCameraCallBack(dvpHandle handle, dvpStreamEvent event, void* pContext, dvpFrame* pFrame, void* pBuffer)
{
	DSCamera* pThis = (DSCamera*)pContext;
	
	//基类通用变量
	pThis->frameId = pFrame->uFrameID;
	
	//回调取图
	cv::Mat mat = cv::Mat(pFrame->iHeight, pFrame->iWidth, CV_8UC3, (uchar*)pBuffer, pFrame->iWidth * 3).clone();

	return 0;
}

void DSCamera::init(CameraManagePara cmPara)
{
	connect(cmPara);
}

bool DSCamera::setParameter(CameraThreadPara para)
{
	dvpStatus status;
	//关闭流
	status = dvpStop(handle);
	
	//设置相机参数等等

	//开启流
	status = dvpStart(handle);
	return true;
}

bool DSCamera::isOnline()
{
	if (!isValidHandle())
		return false;

	dvpStatus status;
	bool online = false;
	status = dvpIsOnline(handle, &online);
	if (status != DVP_STATUS_OK)
	{
		LOG(ERROR) << " get online status error " << std::endl;
		return false;
	}
	return online;
}

void DSCamera::close()
{
	//关闭视频流
	dvpStatus status = dvpStop(handle);

	//关闭相机
	dvpStatus status1 = dvpClose(handle);
}

bool DSCamera::isValidHandle()
{
	bool isValid = false;
	dvpStatus status = dvpIsValid(handle, &isValid);
	if (status != DVP_STATUS_OK) {
		return false;
	}
	return isValid;
}

void DSCamera::stopGrab()
{
	dvpStatus status = dvpStop(handle);
}

void DSCamera::connect(CameraManagePara cmPara)
{
	dvpStatus status;

	status = dvpOpenByUserId(name.c_str(), OPEN_NORMAL, &handle);

	//设置相机属性-略

	//设置回调
	status = dvpRegisterStreamCallback(handle, dSCameraCallBack, STREAM_EVENT_FRAME_THREAD, this);

}

3.抽象工厂

通过工厂来创建具体子类对象。

cpp 复制代码

#ifndef _ICAMERAFACTORY_H_
#define _ICAMERAFACTORY_H_

#include "ICamera.h"
#include "DSCamera.h"
#include "DHCamera.h"
#include "MDWSCamera.h"

class ICameraFactory
{
public:
    virtual ~ICameraFactory() = default;
    // 创建对应厂商相机实例
    virtual ICamera* createCamera(std::string cameraName, std::string picPath) = 0;
};

class DSCameraFactory : public ICameraFactory
{
public:
    ICamera* createCamera(std::string cameraName, std::string picPath) override
    {
        return new DSCamera(cameraName, picPath);
    }

};

class DHCameraFactory : public ICameraFactory
{
public:
    ICamera* createCamera(std::string cameraName, std::string picPath) override
    {
        return new DHCamera(cameraName, picPath);
    }

};

class MDWSCameraFactory : public ICameraFactory
{
public:
	ICamera* createCamera(std::string cameraName, std::string picPath) override
	{
		return new MDWSCamera(cameraName, picPath);
	}

};

class CameraFactoryManager
{
public:
	// 根据相机类型创建相机实例
	static ICamera* createCamera(const std::string& camType, const std::string& camName, const std::string& picPath)
	{
		if (camType == "DS") {
			return DSCameraFactory{}.createCamera(camName, picPath);
		}
		else if (camType == "DH")
		{
			return DHCameraFactory{}.createCamera(camName, picPath);
		}
		else if (camType == "MDWS")
		{
			MDWSCameraFactory factory;
			return MDWSCameraFactory{}.createCamera(camName, picPath);
		}
		else
		{
			throw std::runtime_error("unsupported camera type: " + camType);
		}

	}

};

#endif // !_ICAMERAFACTORY_H_