在Qt中實現工廠模式可以通過多種方式，具體選擇取決于需求和場景。以下是幾種常見的實現方法：

1. 簡單工廠模式通過一個工廠類根據參數創建不同對象。cppclass Shape {public: virtual void draw() = 0; virtual ~Shape() = default;};class Circle : public Shape {public: void draw() override { qDebug() << "Drawing Circle"; }};class Rectangle : public Shape {public: void draw() override { qDebug() << "Drawing Rectangle"; }};class ShapeFactory {public: static Shape* createShape(const QString& type) { if (type == "Circle") return new Circle(); if (type == "Rectangle") return new Rectangle(); return nullptr; }};// 使用Shape* circle = ShapeFactory::createShape("Circle");circle->draw(); // 輸出: Drawing Circle### 2. **動態注冊工廠（擴展性好）**使用注冊表動態注冊創建函數，支持擴展。cppclass ShapeFactory {public: using Creator = std::function<Shape*()>; static void registerCreator(const QString& type, Creator creator) { creators()[type] = creator; } static Shape* create(const QString& type) { auto it = creators().find(type); return (it != creators().end()) ? it->second() : nullptr; }private: static QMap<QString, Creator>& creators() { static QMap<QString, Creator> instance; return instance; }};// 注冊具體類struct CircleRegistrar { CircleRegistrar() { ShapeFactory::registerCreator("Circle", []{ return new Circle; }); }} static circleRegistrar;// 使用Shape* shape = ShapeFactory::create("Circle");### 3. **利用Qt元對象系統（QObject派生類）**通過類名動態創建對象，需配合Qt的元對象系統。cppclass Shape : public QObject { Q_OBJECTpublic: virtual void draw() = 0;};class Circle : public Shape { Q_OBJECTpublic: void draw() override { qDebug() << "Circle"; }};// 注冊元類型Q_DECLARE_METATYPE(Circle*)qRegisterMetaType<Circle*>();// 使用類名創建實例const QMetaObject* meta = QMetaType::metaObjectForType(QMetaType::type("Circle"));Shape* obj = qobject_cast<Shape*>(meta->newInstance());### 4. Qt插件系統結合工廠模式動態加載插件并創建實例，適合擴展應用。接口定義 (shapeplugin.h):cpp#include <QtPlugin>class Shape {public: virtual void draw() = 0; virtual ~Shape() = default;};#define ShapeInterface_iid "com.example.ShapeInterface"Q_DECLARE_INTERFACE(Shape, ShapeInterface_iid)插件實現 (circleplugin.cpp):cppclass CirclePlugin : public QObject, public Shape { Q_OBJECT Q_PLUGIN_METADATA(IID ShapeInterface_iid FILE "circle.json") Q_INTERFACES(Shape)public: void draw() override { qDebug() << "Circle Plugin"; }};#include "circleplugin.moc"加載插件:cppQPluginLoader loader("circleplugin.dll");QObject* plugin = loader.instance();if (plugin) { Shape* shape = qobject_cast<Shape*>(plugin); shape->draw(); // 輸出: Circle Plugin}### 總結- 簡單工廠：適用于類型較少且不常變化的場景。- 動態注冊：擴展性好，新增類型無需修改工廠。- 元對象系統：適合QObject派生類，利用Qt的反射機制。- 插件系統：實現動態擴展，適用于模塊化設計。根據具體需求選擇合適的方式，確保代碼的靈活性和可維護性。