class MyStylePlugin : public QStylePlugin
{
    Q_OBJECT
    Q_PLUGIN_METADATA(IID \
                        "org.qt-project.Qt.QStyleFactoryInterface" \
                        FILE
                        "mystyleplugin.json")
public:
    QStyle *create(const QString &key);
};

#include "mystyleplugin.h"
QStyle *MyStylePlugin::create(const QString &key)
{
    if (key.toLower() == "mystyle")
        return new MyStyle;
    return 0;
}

TEMPLATE      = lib
# 动态库的
CONFIG       += plugin
# 静态库的
#CONFIG       += plugin static
QT           += widgets
TARGET        = $$qtLibraryTarget(sharePlugin)
DESTDIR       = ../../plugins
HEADERS += \
    Interface.h \
    SharePlugin.h
SOURCES += \
    SharePlugin.cpp

#ifndef INTERFACE_H
#define INTERFACE_H
#include <QString>
#include <QtPlugin>
class Interface
{
public:
    virtual ~Interface(){}
    virtual QString getSerailData() = 0;                // 序列化
    virtual void setSerailData(const QString data) = 0; // 序列化设置
    virtual void show() = 0;                            // 显示窗口
};
#define Interface_iid "MyPlugin.Interface"
Q_DECLARE_INTERFACE(Interface, Interface_iid)
#endif // INTERFACE_H

#ifndef SHAREPLUGIN_H
#define SHAREPLUGIN_H
/************************************************************\
 * 控件名称：SharePlugin
 * 控件描述：动态插件模板，生成插件部分
 * 作者：红模仿    联系方式：QQ21497936
 * 博客地址：https://blog.csdn.net/qq21497936
 *       日期             版本               描述
 *   2020年04月10日      v1.0.0            基础模板
\************************************************************/
#include <QObject>
#include <QtPlugin>
#include "Interface.h"
class SharePlugin : public QObject, public Interface
{
    Q_OBJECT
    Q_INTERFACES(Interface)                         // Q_INTERFACES宏用于告诉Qt该类实现的接口。
    Q_PLUGIN_METADATA(IID Interface_iid)            // Q_PLUGIN_METADATA宏用于描述插件元数据
public:
    explicit SharePlugin(QObject *parent = 0);
    virtual QString getSerailData();                // 序列化
    virtual void setSerailData(const QString data); // 序列化设置
    virtual void show();                            // 显示窗口
private:
    QString _data;                                  // 序列化
};
#endif // SHAREPLUGIN_H

#include "SharePlugin.h"
#include <QDebug>
#include <QWidget>
SharePlugin::SharePlugin(QObject *parent)
    : QObject(parent),
    _data("null")
{
}
void SharePlugin::setSerailData(const QString data)
{
    _data = data;
    qDebug() << __FILE__ << __LINE__ << __FUNCTION__ << _data;
}
QString SharePlugin::getSerailData()
{
    qDebug() << __FILE__ << __LINE__ << __FUNCTION__ << _data;
    return _data;
}
void SharePlugin::show()
{
    QWidget *pWidget = new QWidget;
    pWidget->setWindowTitle("test SharePlugin");
    pWidget->show();
}

bool Widget::loadPlugin()
{
    // 热加载插件
    // 获取当前应用程序所在的路径
    QDir pluginsDir(qApp->applicationDirPath());
    // 切换到插件路径(判断是否输出到debug和release,目前是在pro中直接输出到../../app目录)
    if(pluginsDir.dirName().toLower() == "debug" || pluginsDir.dirName().toLower() == "release")
    {
        // 返回上一级目录
        pluginsDir.cdUp();
    }
    // 切换到插件目录
    pluginsDir.cdUp();
    pluginsDir.cdUp();
    pluginsDir.cd("plugins");
    // 打开对应的插件
    // 引入静态插件需要将静态编译的库，编译的时候就要引入进去
    // 实测静态插件，debug调用release版本插件可行，反过来也可行
    // 实测动态插件，debug调用release版本插件不可行，反过来也不可行
    QString pluginDllName = "sharePlugin.dll";    // release版本插件（注意：release下只能加载release版本的插件）
//    QString pluginDllName = "sharePlugind.dll";     // debug版本插件（注意：debug下只能加载debug版本的插件）
    QString dllPath = pluginsDir.absolutePath() + QDir::separator() + pluginDllName;
    if(!QFile::exists(dllPath))
    {
        qDebug() << __FILE__ << __LINE__
                 << "Not exist file:" << dllPath;
        return false;
    }
    // 加载插件
    QPluginLoader pluginLoader(dllPath);
    pluginLoader.load();
    qDebug() << __FILE__ << __LINE__ << pluginLoader.isLoaded();
    QObject *pPlugin = pluginLoader.instance();
    if(pPlugin)
    {
        QString pluginName = pPlugin->metaObject()->className();
        qDebug() << __FILE__ << __LINE__ << "Succeed to get plugin class Name:" << pluginName;
        //对插件初始化
        if(pluginName == "SharePlugin")
        {
           _pInterface = qobject_cast<Interface *>(pPlugin);
           if (_pInterface)
           {
                qDebug() << __FILE__ << __LINE__ << "Succeed to load SharePlugin";
           }else{
                qDebug() << __FILE__ << __LINE__ << "Failed to load SharePlugin";
           }
        }
    }else{
        qDebug() << __FILE__ << __LINE__ << "Failed to load plugin:" << dllPath;
        return false;
    }
    return true;
}

void Widget::on_pushButton_testSharePlugin_clicked()
{
    if(_pInterface)
    {
        qDebug() << __FILE__ << __LINE__ << _pInterface->getSerailData();
        _pInterface->setSerailData("hello world!!!");
        qDebug() << __FILE__ << __LINE__ << _pInterface->getSerailData();
        _pInterface->show();
    }
}

#ifndef STATICINTERFACE_H
#define STATICINTERFACE_H
#include <QString>
#include <QtPlugin>
class StaticInterface
{
public:
    virtual ~StaticInterface(){}
    virtual QString getSerailData() = 0;                // 序列化
    virtual void setSerailData(const QString data) = 0; // 序列化设置
    virtual void show() = 0;                            // 显示窗口
};
#define StaticInterface_idd "MyPlugin.StaticInterface"
Q_DECLARE_INTERFACE(StaticInterface, StaticInterface_idd)
#endif // STATICINTERFACE_H

#include "StaticPlugin.h"
#include <QDebug>
#include <QWidget>
StaticPlugin::StaticPlugin(QObject *parent)
    : QObject(parent),
      _data("null")
{
}
void StaticPlugin::setSerailData(const QString data)
{
    _data = data;
    qDebug() << __FILE__ << __LINE__ << __FUNCTION__ << _data;
}
QString StaticPlugin::getSerailData()
{
    qDebug() << __FILE__ << __LINE__ << __FUNCTION__ << _data;
    return _data;
}
void StaticPlugin::show()
{
    QWidget *pWidget = new QWidget;
    pWidget->setWindowTitle("test StaticPlugin");
    pWidget->show();
}
测试Demo的pro工程文件：testStaticDemo.pro
#-------------------------------------------------
#
# Project created by QtCreator 2020-04-09T15:36:39
#
#-------------------------------------------------
QT       += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = testDemo
TEMPLATE = app
#DESTDIR  = ../../app
# The following define makes your compiler emit warnings if you use
# any feature of Qt which has been marked as 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 you use 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 \
        StaticWidget.cpp
HEADERS += \
        StaticWidget.h
FORMS += \
        StaticWidget.ui
# 引入静态插件需要将静态编译的库，编译的时候就要引入进去
# 实测静态插件，debug调用release版本插件可行，反过来也可行
# 实测动态插件，debug调用release版本插件不可行，反过来也不可行
CONFIG(debug, debug|release) {
    LIBS += -L../../plugins
    LIBS += -lstaticPlugind
} else {
    LIBS += -L../../plugins
    LIBS += -lstaticPlugin
}

bool StaticWidget::loadStaticPlugin()
{
    bool ret = false;
    for(int index = 0; index < QPluginLoader::staticInstances().size(); index++)
    {
        QObject *pStaticPlugin = QPluginLoader::staticInstances().at(index);
        _pStaticInterface = qobject_cast<StaticInterface *>(pStaticPlugin);
       if (_pStaticInterface)
       {
            qDebug() << __FILE__ << __LINE__ << "Succeed to load StaticInterface:" << pStaticPlugin->metaObject()->className();
            ret = true;
       }
    }
    if(!ret)
    {
        qDebug() << __FILE__ << __LINE__ << "Failed to load StaticInterface";
        return false;
    }
    return true;
}

void StaticWidget::on_pushButton_testStaticPlugin_clicked()
{
    if(_pStaticInterface)
    {
        qDebug() << __FILE__ << __LINE__ << _pStaticInterface->getSerailData();
        _pStaticInterface->setSerailData("hello world!!!");
        qDebug() << __FILE__ << __LINE__ << _pStaticInterface->getSerailData();
        _pStaticInterface->show();
    }
}