橋接模式

桥接模式是软件设计模式中最复杂的模式之一，它把事物对象和其具体行为、具体特征分离开来，使它们可以各自独立的变化。事物对象仅是一个抽象的概念。如“圆形”、“三角形”归于抽象的“形状”之下，而“画圆”、“画三角”归于实现行为的“画图”类之下，然后由“形状”调用“画图”。

示例

下列各语言的代码都用于写出两个不同的圆的坐标和半径。

API1.circle at 1:2 7.5
API2.circle at 5:7 27.5

Java

/** "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#

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类库的C#

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++

#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;}