本文共 2246 字，大约阅读时间需要 7 分钟。
享元模式（Flyweight Pattern）主要用于减少创建对象的数量，以减少内存占用和提高性能。这种类型的设计模式属于结构型模式，它提供了减少对象数量从而改善应用所需的对象结构的方式。享元模式尝试重用现有的同类对象，如果未找到匹配的对象，则创建新对象。
代码:
#include #include #include #include using namespace std;class Shape{public: virtual void draw() = 0; virtual ~Shape(){}};class Circle : public Shape{public: Circle(string color, int x=0, int y=0, int radius=0) :_color(color), _x(x), _y(y), _radius(radius){} void setX(int x) { _x = x; } void setY(int y) { _y = y; } void setRadius(int radius) { _radius = radius; } void set(int x, int y) { _x = x; _y = y; } virtual void draw() { cout << "Draw circle [color:" << _color << ", at(" << _x<< ","<< _y << "), radius("<< _radius << ")]" << endl; }private: int _x; int _y; int _radius; string _color; //内部状态};class CircleFactory{public: CircleFactory() { _map.clear(); } Circle *getCircle(string color) { if (_map.find(color) == _map.end()) { int x, y; x = getRandomXY(); y = getRandomXY(); Circle *c = new Circle(color, x, y); c->setRadius(100); _map[color] = c; return c; } return _map[color]; } ~CircleFactory() { for (auto it = _map.begin(); it != _map.end(); ++it) { delete it->second; } } int getRandomXY() { return rand() % 100; } int getCricleCount() { return _map.size(); } string getRandomColor() { static string colors[] = { "red", "Green", "blue", "white", "black", "purple", "yellow", "orange"}; static int len = sizeof(colors) / sizeof(*colors); int index = rand() % len; return colors[index]; } private: map _map;};void test(){ srand(time(NULL)); CircleFactory cf; Circle *c = NULL; for (int i = 0; i < 10; ++i) { string color = cf.getRandomColor(); c = cf.getCircle(color); c->draw(); }}int main(){ test(); cin.get(); return 0;}
效果:
转载于:https://www.cnblogs.com/hupeng1234/p/6798289.html
