橋接模式
橋接模式是軟件設計模式中最複雜的模式之一，它把事物對象和其具體行爲、具體特徵分離開來，使它们可以各自独立的变化。事物對象僅是一個抽象的概念。如“圓形”、“三角形”歸于抽象的“形狀”之下，而“畫圓”、“畫三角”歸于實現行爲的“畫圖”類之下，然後由“形狀”調用“畫圖”。
結構
[编辑]
- Abstraction
- 定義抽象的介面
- 該介面包含實現具體行爲、具體特徵的Implementor介面
- Refined Abstraction
- 抽象介面Abstraction的子類，依舊是一個抽象的事物名
- Implementor
- 定義具體行爲、具體特徵的應用介面
- ConcreteImplementor
- 實現Implementor介面
示例
[编辑]下列各語言的代碼都用於寫出兩個不同的圓的坐標和半徑。
API1.circle at 1:2 7.5 API2.circle at 5:7 27.5
Java
[编辑]/** "Implementor" */ interface DrawingAPI { public void drawCircle(double x, double y, double radius); } /** "ConcreteImplementor" 1/2 */ class DrawingAPI1 implements DrawingAPI { public void drawCircle(double x, double y, double radius) { System.out.printf("API1.circle at %f:%f radius %f\n", x, y, radius); } } /** "ConcreteImplementor" 2/2 */ class DrawingAPI2 implements DrawingAPI { public void drawCircle(double x, double y, double radius) { System.out.printf("API2.circle at %f:%f radius %f\n", x, y, radius); } } /** "Abstraction" */ interface Shape { public void draw(); // low-level public void resizeByPercentage(double pct); // high-level } /** "Refined Abstraction" */ class CircleShape implements Shape { private double x, y, radius; private DrawingAPI drawingAPI; public CircleShape(double x, double y, double radius, DrawingAPI drawingAPI) { this.x = x; this.y = y; this.radius = radius; this.drawingAPI = drawingAPI; } // low-level i.e. Implementation specific public void draw() { drawingAPI.drawCircle(x, y, radius); } // high-level i.e. Abstraction specific public void resizeByPercentage(double pct) { radius *= pct; } } /** "Client" */ class BridgePattern { public static void main(String[] args) { Shape[] shapes = new Shape[2]; shapes[0] = new CircleShape(1, 2, 3, new DrawingAPI1()); shapes[1] = new CircleShape(5, 7, 11, new DrawingAPI2()); for (Shape shape : shapes) { shape.resizeByPercentage(2.5); shape.draw(); } } } C#
[编辑] using System; /** "Implementor" */ interface IDrawingAPI { void DrawCircle(double x, double y, double radius); } /** "ConcreteImplementor" 1/2 */ class DrawingAPI1 : IDrawingAPI { public void DrawCircle(double x, double y, double radius) { System.Console.WriteLine("API1.circle at {0}:{1} radius {2}", x, y, radius); } } /** "ConcreteImplementor" 2/2 */ class DrawingAPI2 : IDrawingAPI { public void DrawCircle(double x, double y, double radius) { System.Console.WriteLine("API2.circle at {0}:{1} radius {2}", x, y, radius); } } /** "Abstraction" */ interface IShape { void Draw(); // low-level (i.e. Implementation-specific) void ResizeByPercentage(double pct); // high-level (i.e. Abstraction-specific) } /** "Refined Abstraction" */ class CircleShape : IShape { private double x, y, radius; private IDrawingAPI drawingAPI; public CircleShape(double x, double y, double radius, IDrawingAPI drawingAPI) { this.x = x; this.y = y; this.radius = radius; this.drawingAPI = drawingAPI; } // low-level (i.e. Implementation-specific) public void Draw() { drawingAPI.DrawCircle(x, y, radius); } // high-level (i.e. Abstraction-specific) public void ResizeByPercentage(double pct) { radius *= pct; } } /** "Client" */ class BridgePattern { public static void Main(string[] args) { IShape[] shapes = new IShape[2]; shapes[0] = new CircleShape(1, 2, 3, new DrawingAPI1()); shapes[1] = new CircleShape(5, 7, 11, new DrawingAPI2()); foreach (IShape shape in shapes) { shape.ResizeByPercentage(2.5); shape.Draw(); } } } 用generics類庫的C#
[编辑] using System; /** "Implementor" */ interface IDrawingAPI { void DrawCircle(double x, double y, double radius); } /** "ConcreteImplementor" 1/2 */ struct DrawingAPI1 : IDrawingAPI { public void DrawCircle(double x, double y, double radius) { System.Console.WriteLine("API1.circle at {0}:{1} radius {2}", x, y, radius); } } /** "ConcreteImplementor" 2/2 */ struct DrawingAPI2 : IDrawingAPI { public void DrawCircle(double x, double y, double radius) { System.Console.WriteLine("API2.circle at {0}:{1} radius {2}", x, y, radius); } } /** "Abstraction" */ interface IShape { void Draw(); // low-level (i.e. Implementation-specific) void ResizeByPercentage(double pct); // high-level (i.e. Abstraction-specific) } /** "Refined Abstraction" */ class CircleShape<T> : IShape where T : struct, IDrawingAPI { private double x, y, radius; private static IDrawingAPI drawingAPI = new T(); public CircleShape(double x, double y, double radius) { this.x = x; this.y = y; this.radius = radius; } // low-level (i.e. Implementation-specific) public void Draw() { drawingAPI.DrawCircle(x, y, radius); } // high-level (i.e. Abstraction-specific) public void ResizeByPercentage(double pct) { radius *= pct; } } /** "Client" */ class BridgePattern { public static void Main(string[] args) { IShape[] shapes = new IShape[2]; shapes[0] = new CircleShape<DrawingAPI1>(1, 2, 3); shapes[1] = new CircleShape<DrawingAPI2>(5, 7, 11); foreach (IShape shape in shapes) { shape.ResizeByPercentage(2.5); shape.Draw(); } } }
C++
[编辑]#include <iostream> using namespace std; /* Implementor*/ class DrawingAPI { public: virtual void drawCircle(double x, double y, double radius) = 0; virtual ~DrawingAPI() {} }; /* Concrete ImplementorA*/ class DrawingAPI1 : public DrawingAPI { public: void drawCircle(double x, double y, double radius) { cout << "API1.circle at " << x << ':' << y << ' ' << radius << endl; } }; /* Concrete ImplementorB*/ class DrawingAPI2 : public DrawingAPI { public: void drawCircle(double x, double y, double radius) { cout << "API2.circle at " << x << ':' << y << ' ' << radius << endl; } }; /* Abstraction*/ class Shape { public: virtual ~Shape() {} virtual void draw() = 0; virtual void resizeByPercentage(double pct) = 0; }; /* Refined Abstraction*/ class CircleShape : public Shape { public: CircleShape(double x, double y,double radius, DrawingAPI *drawingAPI) : m_x(x), m_y(y), m_radius(radius), m_drawingAPI(drawingAPI) {} void draw() { m_drawingAPI->drawCircle(m_x, m_y, m_radius); } void resizeByPercentage(double pct) { m_radius *= pct; } private: double m_x, m_y, m_radius; DrawingAPI *m_drawingAPI; }; int main(void) { DrawingAPI1 dap1; DrawingAPI2 dap2; CircleShape circle1(1,2,3,&dap1); CircleShape circle2(5,7,11,&dap2); circle1.resizeByPercentage(2.5); circle2.resizeByPercentage(2.5); circle1.draw(); circle2.draw(); return 0; } Python
[编辑]# Implementor class DrawingAPI: def drawCircle(x, y, radius): pass # ConcreteImplementor 1/2 class DrawingAPI1(DrawingAPI): def drawCircle(self, x, y, radius): print "API1.circle at %f:%f radius %f" % (x, y, radius) # ConcreteImplementor 2/2 class DrawingAPI2(DrawingAPI): def drawCircle(self, x, y, radius): print "API2.circle at %f:%f radius %f" % (x, y, radius) # Abstraction class Shape: # low-level def draw(self): pass # high-level def resizeByPercentage(self, pct): pass # Refined Abstraction class CircleShape(Shape): def __init__(self, x, y, radius, drawingAPI): self.__x = x self.__y = y self.__radius = radius self.__drawingAPI = drawingAPI # low-level i.e. Implementation specific def draw(self): self.__drawingAPI.drawCircle(self.__x, self.__y, self.__radius) # high-level i.e. Abstraction specific def resizeByPercentage(self, pct): self.__radius *= pct def main(): shapes = [ CircleShape(1, 2, 3, DrawingAPI1()), CircleShape(5, 7, 11, DrawingAPI2()) ] for shape in shapes: shape.resizeByPercentage(2.5) shape.draw() if __name__ == "__main__": main()