桥接模式 Bridge Pattern

一、什么是桥接模式
Bridge 模式又叫做桥接模式，是构造型的设计模式之一。Bridge模式基于类的最小设计原则，通过使用封装，聚合以及继承等行为来让不同的类承担不同的责任。它的主要特点是把抽象（abstraction）与行为实现（implementation）分离开来，从而可以保持各部分的独立性以及应对它们的功能扩展。

二、桥接模式的结构



三、桥接模式的角色和职责
Client

  Bridge模式的使用者

  抽象类接口（接口或抽象类）

  维护对行为实现（Implementor）的引用

Refined Abstraction

  Abstraction子类

Implementor

  行为实现类接口 (Abstraction接口定义了基于Implementor接口的更高层次的操作)

ConcreteImplementor

  Implementor子类

Car.java
package com.ibeifeng.eg3; 

public abstract class Car { 
    private Engine engine; 
 
    public Car(Engine engine) { 
        this.engine = engine; 
    } 
 
    public Engine getEngine() { 
        return engine; 
    } 
 
    public void setEngine(Engine engine) { 
        this.engine = engine; 
    } 
 
    public abstract void installEngine(); 
}
Bus.java
package com.ibeifeng.eg3; 

public class Bus extends Car{ 
 
    public Bus(Engine engine) { 
        super(engine); 
    } 
 
    public void installEngine() { 
        System.out.print("Bus："); 
        this.getEngine().installEngine(); 
    } 
}

Jeep.java
package com.ibeifeng.eg3; 

public class Jeep extends Car { 
 
    public Jeep(Engine engine) { 
        super(engine); 
    } 
 
    public void installEngine() { 
        System.out.print("Jeep："); 
        this.getEngine().installEngine(); 
    } 
 
}
Engine.java
package com.ibeifeng.eg3; 

public interface Engine { 
    public void installEngine(); 
}
Engine2000.java
package com.ibeifeng.eg3; 

public class Engine2000 implements Engine { 
 
    public void installEngine() { 
        System.out.println("安装2000cc发动机"); 
    } 
 
}
Engine2200.java
package com.ibeifeng.eg3; 

public class Engine2200 implements Engine{ 
 
    public void installEngine() { 
        System.out.println("安装2200cc发动机"); 
    } 
 
}
MainClass.java
package com.ibeifeng.eg3; 

public class MainClass { 
    public static void main(String[] args) { 
 
        Engine engine2000 = new Engine2000(); 
        Engine engine2200 = new Engine2200(); 
 
        Car car1 = new Bus(engine2000); 
        car1.installEngine(); 
 
        Car car2 = new Bus(engine2200); 
        car2.installEngine(); 
 
        Car jeep1 = new Jeep(engine2000); 
        jeep1.installEngine(); 
 
        Car jeep2 = new Jeep(engine2200); 
        jeep2.installEngine(); 
 
    } 
}