设计模式-桥接模式

Posted 2022-08-19 guanbin-529

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桥接模式的适用环境：

1.如果一个系统需要在构件的抽象化角色和具体化角色之间增加更多的灵活性，避免在两个层次之间建立静态的继承联系，通过桥接模式可以使它们在抽象层建立一个关联关系。
2、对于那些不希望使用继承或因为多层次继承导致系统类的个数急剧增加的系统，桥接模式尤为适用。
3、一个类存在两个独立变化的维度，且这两个维度都需要进行扩展。

注意事项：对于两个独立变化的维度，使用桥接模式再适合不过了。

示例:

交通工具：car、bus、bike是一类，共同点是可以行驶即run；
道路：城市道路、乡村道路、山路等是一类；
用road抽象类（桥接类），维护行为的实现

创建RunApi及car、bus、bike的实现

package com.design.demo.bridge;

/**
 * @author: GuanBin
 * @date: Created in 下午10:18 2019/8/23
 */
public interface RunApi 
    /**
     * @param speed 速度 km/h
     * @param hour  时间 h
     */
    public void run(int speed, int hour);

package com.design.demo.bridge;

/**
 * @author: GuanBin
 * @date: Created in 下午10:24 2019/8/23
 */
public class CarRun implements RunApi 

    @Override
    public void run(int speed, int hour) 
        System.out.println("The car ran " + speed * hour + " kilometers at a  speed of " + speed + " km/h per hour.");

package com.design.demo.bridge;

/**
 * @author: GuanBin
 * @date: Created in 下午10:24 2019/8/23
 */
public class BusRun implements RunApi 

    @Override
    public void run(int speed, int hour) 
        System.out.println("The bus ran " + speed * hour + " kilometers at a  speed of " + speed + " km/h per hour.");

package com.design.demo.bridge;

/**
 * @author: GuanBin
 * @date: Created in 下午10:24 2019/8/23
 */
public class BikeRun implements RunApi 

    @Override
    public void run(int speed,int hour) 
        System.out.println("The bike ran " + speed * hour + " kilometers at a  speed of " + speed + " km/h per hour.");

桥接类Road 及UnbanRoad

package com.design.demo.bridge;

/**
 * @author: GuanBin
 * @date: Created in 下午10:30 2019/8/23
 */
public abstract class Road 
    protected RunApi runApi;

    public Road(RunApi runApi) 
        this.runApi = runApi;
    

    public abstract void runDistance();

package com.design.demo.bridge;

/**
 * @author: GuanBin
 * @date: Created in 下午10:34 2019/8/23
 */
public class UrbanRoad extends Road 

    private int speed;
    private int hour;

    public UrbanRoad(RunApi runApi, int speed, int hour) 
        super(runApi);
        this.speed = speed;
        this.hour = hour;
    

    @Override
    public void runDistance() 
        runApi.run(speed, hour);

Client类

package com.design.demo.bridge;

/**
 * @author: GuanBin
 * @date: Created in 下午10:40 2019/8/23
 */
public class Client 
    public static void main(String[] args) 

        UrbanRoad carRunUrbanRD = new UrbanRoad(new CarRun(), 90,2);
        UrbanRoad busRunUrbanRD = new UrbanRoad(new BusRun(), 60,2);
        UrbanRoad bikeRunUrbanRD = new UrbanRoad(new BikeRun(), 10,2);

        carRunUrbanRD.runDistance();
        busRunUrbanRD.runDistance();
        bikeRunUrbanRD.runDistance();

输出：

The car ran 180 kilometers at a  speed of 90 km/h per hour.
The bus ran 120 kilometers at a  speed of 60 km/h per hour.
The bike ran 20 kilometers at a  speed of 10 km/h per hour.