桥接模式

桥接模式又称桥梁模式，在软件系统中某些类型由于自身的逻辑，具有两个或多个维度的变化，如何应对这种多维度的变化？桥接模式使得软件系统能够轻松的沿着多个方向变化，而又不引入额外的复杂度。

桥接模式的用意是“将抽象化和实现化脱耦，使得二者可以独自的变化”。

以电灯开关为例：

所有电灯接口：

package com.demo.bridge.light;public interface ILight {public void turnOn();public void keepLight();public void turnOff();}

开关基类：

package com.demo.bridge.baseswitch;import com.demo.bridge.light.ILight;public class BaseSwitch {public ILight light;public BaseSwitch(ILight light){this.light = light;}public final void makeLight(){this.light.turnOn();this.light.keepLight();this.light.turnOff();}}

普通电灯、和可变色电灯实现电灯接口：

package com.demo.bridge.light;public class CommonLighe implements ILight {@Overridepublic void turnOn() {System.out.println("普通白织灯打开");}@Overridepublic void keepLight() {System.out.println("普通白织灯亮开");}@Overridepublic void turnOff() {System.out.println("普通白织灯关闭");}}

package com.demo.bridge.light;public class ChangeableColorLight implements ILight {@Overridepublic void turnOn() {System.out.println("彩灯打开");}@Overridepublic void keepLight() {System.out.println("彩灯亮着");}@Overridepublic void turnOff() {System.out.println("彩灯关闭 ");}}

定义一个远程遥控开关，继承开发基类，控制灯色：

package com.demo.bridge.baseswitch;import com.demo.bridge.light.ILight;public class RemoteSwitch extends BaseSwitch {public RemoteSwitch(ILight light) {super(light);}public void remoteColorSwitch(int pa){this.light.turnOn();this.light.keepLight();String color = "";switch(pa){case 1: color = "暖色";break;case 2:color = "蓝色";break;default:color = "黄色";break;}System.out.println("灯变成"+color);this.light.turnOff();}}

测试：

package com.demo.bridge;import com.demo.bridge.baseswitch.BaseSwitch;import com.demo.bridge.baseswitch.RemoteSwitch;import com.demo.bridge.light.ChangeableColorLight;import com.demo.bridge.light.CommonLighe;import com.demo.bridge.light.ILight;public class Client {/** * @param args */public static void main(String[] args) {ILight common = new CommonLighe();ILight changeableColorLight = new ChangeableColorLight();System.out.println("-- 白炽灯 --");BaseSwitch baseSwitch = new BaseSwitch(common);baseSwitch.makeLight();System.out.println("");System.out.println("-- 彩灯 --");RemoteSwitch remoteSwitch = new RemoteSwitch(changeableColorLight);remoteSwitch.remoteColorSwitch(2);}}

控制台结果：

-- 白炽灯 --普通白织灯打开普通白织灯亮开普通白织灯关闭-- 彩灯 --彩灯打开彩灯亮着灯变成蓝色彩灯关闭