一、前言

注册服务的时候能够用服务工厂来注册；

访问服务getServeice中的plugin参数是执行ctkPluginContext::getService(const ctkServiceReference&)的插件，从而工厂根据执行的不同插件名称返回不同的服务实现

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服务工厂的作用

• 在服务中可以知道是哪个其它插件在使用它；
• 懒汉式使用服务，需要的时候才new；
• 厂其它插件使用服务工厂和使用无服务工的服务，没有任何区别，代码都一样；
• 可根据需要创建多种实现的服务，就是多种服务对应一个插件；

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二、新建插件

插件结构

• HelloService.h：接口类
• HelloImpl.h：实现类
• HelloActivator.h：激活类
• ServiceFactory.h：服务工厂

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工程文件：Hello.pro

QT += core
QT -= gui

TEMPLATE = lib
CONFIG += plugin
TARGET = Hello
DESTDIR = $$OUT_PWD/bin/plugins

include($$PWD/../CTK/CTK_dependency.pri)

HEADERS += \
    HelloActivator.h \
    HelloImpl.h \
    HelloService.h \
    ServiceFactory.h

RESOURCES += \
    qresource.qrc

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接口类：HelloService.h

#ifndef HELLOSERVICE_H
#define HELLOSERVICE_H

#include <QtPlugin>

class HelloService
{
public:
    virtual ~HelloService() {}
    virtual void sayHello() = 0;
};

#define HelloService_iid "org.commontk.service.demos.HelloService"
Q_DECLARE_INTERFACE(HelloService, HelloService_iid)

#endif // HELLOSERVICE_H

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实现类：HelloImpl.h

#ifndef HELLOIMPL_H
#define HELLOIMPL_H

#include "HelloService.h"
#include <QObject>
#include <QtDebug>

// HelloWorld
//---------------------------------------------------------
class HelloWorldImpl : public QObject, public HelloService
{
    Q_OBJECT
    Q_INTERFACES(HelloService)

public:
    void sayHello() Q_DECL_OVERRIDE {
        qDebug() << "Hello,World!";
    }
};

// HelloCTK
//---------------------------------------------------------
class HelloCTKImpl : public QObject, public HelloService
{
    Q_OBJECT
    Q_INTERFACES(HelloService)

public:
    void sayHello() Q_DECL_OVERRIDE {
        qDebug() << "Hello,CTK!";
    }
};

#endif // HELLOIMPL_H

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激活类：HelloActivator.h

#ifndef HELLOACTIVATOR_H
#define HELLOACTIVATOR_H

#include <ctkPluginActivator.h>
#include <ctkPluginContext.h>
#include "HelloService.h"
#include "ServiceFactory.h"

class HelloActivator : public QObject, public ctkPluginActivator
{
    Q_OBJECT
    Q_INTERFACES(ctkPluginActivator)
    Q_PLUGIN_METADATA(IID "HELLO")

public:
    // 注册服务工厂
    void start(ctkPluginContext* context) {
        ServiceFactory *factory = new ServiceFactory();
        context->registerService<HelloService>(factory);
    }

    void stop(ctkPluginContext* context) {
        Q_UNUSED(context)
    }
};


#endif // HELLOACTIVATOR_H

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服务工厂：ServiceFactory.h

#ifndef SERVICEFACTORY_H
#define SERVICEFACTORY_H

#include <ctkServiceFactory.h>
#include <ctkPluginConstants.h>
#include <ctkVersion.h>
#include "HelloImpl.h"

class ServiceFactory : public QObject, public ctkServiceFactory
{
    Q_OBJECT
    Q_INTERFACES(ctkServiceFactory)

public:
    ServiceFactory() : m_counter(0) {}

    // 创建服务对象
    QObject* getService(QSharedPointer<ctkPlugin> plugin, ctkServiceRegistration registration) Q_DECL_OVERRIDE {
        Q_UNUSED(registration)

        qDebug() << "Create object of HelloService for: " << plugin->getSymbolicName();
        m_counter++;
        qDebug() << "Number of plugins using service: " << m_counter;

        QHash<QString, QString> headers = plugin->getHeaders();
        ctkVersion version = ctkVersion::parseVersion(headers.value(ctkPluginConstants::PLUGIN_VERSION));
        QString name = headers.value(ctkPluginConstants::PLUGIN_NAME);

        QObject* hello = getHello(version);
        return hello;
    }

    // 释放服务对象
    void ungetService(QSharedPointer<ctkPlugin> plugin, ctkServiceRegistration registration, QObject* service) Q_DECL_OVERRIDE {
        Q_UNUSED(plugin)
        Q_UNUSED(registration)
        Q_UNUSED(service)

        qDebug() << "Release object of HelloService for: "  << plugin->getSymbolicName();
        m_counter--;
        qDebug() << "Number of plugins using service: "  << m_counter;
    }

private:
    // 根据不同的版本，获取不同的服务
    QObject* getHello(ctkVersion version) {
        if (version.toString().contains("alpha")) {
            return new HelloWorldImpl();
        } else {
            return new HelloCTKImpl();
        }
    }

private:
    int m_counter;  // 计数器
};

#endif // SERVICEFACTORY_H

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