桥接模式（Bridge Pattern）
桥接模式（Bridge Pattern）是将抽象部分与它的实现部分分离，使它们都可以独立地变化，使得设计更具扩展性，其实现细节对客户透明。它是一种对象结构型模式，又称为柄体(Handle and Body)模式或接口(interface)模式。在软件系统中，某些类型由于自身的逻辑，它具有两个或多个维度的变化，就需要使用桥接模式（Bridge Pattern）。由于聚合关系建立在抽象层，要求开发者针对抽象化进行设计与编程，这增加了系统的理解与设计难度。
using System;namespace ConsoleApplication{ interface IDrawingAPI { void DrawCircle(double x, double y, double radius); } /** "具体实现" 1/2 */ class DrawingAPI1 : IDrawingAPI { public void DrawCircle(double x, double y, double radius) { Console.WriteLine("API1.circle at {0}:{1} radius {2}", x, y, radius); } } /** "具体实现" 2/2 */ class DrawingAPI2 : IDrawingAPI { public void DrawCircle(double x, double y, double radius) { Console.WriteLine("API2.circle at {0}:{1} radius {2}", x, y, radius); } } /** "抽象" */ interface IShape { void Draw(); void ResizeByPercentage(double pct); } // /** "Refined Abstraction：扩展抽象在下面一层接受更详细的细节。对实现者隐藏更精细的元素。" */ 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; } public void Draw() { drawingAPI.DrawCircle(x, y, radius); } public void ResizeByPercentage(double pct) { radius *= pct; } } /** "Client" */ class Program { 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(); } } }}