设计模式08 桥接模式

桥接模式(Bridge)定义：将抽象与实现分离，使它们可以独立变化。它是用组合关系代替继承关系来实现，从而降低了抽象和实现这两个可变维度的耦合度。

如上图所示，平直的那条"聚合关系"就像一座桥一样。

实现部分：

public interface Implementor {
    public void OperationImpl();
}

public class ConcreteImplementorA implements Implementor {
    @Override
    public void OperationImpl() {
        // TODO Auto-generated method stub
        System.out.println("形状：方形");
    }
}

public class ConcreteImplementorB implements Implementor {
    @Override
    public void OperationImpl() {
        // TODO Auto-generated method stub
        System.out.println("形状：圆形");
    }
}

抽象部分：

public abstract class Abstraction {
    protected Implementor implementor;

    protected Abstraction(Implementor implementor) {
        this.implementor = implementor;
    }
    
    public abstract void Operation();
}

public class RefinedAbstractionA extends Abstraction {
    protected RefinedAbstractionA(Implementor implementor) {
        super(implementor);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void Operation() {
        // TODO Auto-generated method stub
        System.out.println("颜色：红色");
        implementor.OperationImpl();
    }
}

public class RefinedAbstractionB extends Abstraction {
    protected RefinedAbstractionB(Implementor implementor) {
        super(implementor);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void Operation() {
        // TODO Auto-generated method stub
        System.out.println("颜色：黄色");
        implementor.OperationImpl();
    }
}

public class RefinedAbstractionC extends Abstraction {
    protected RefinedAbstractionC(Implementor implementor) {
        super(implementor);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void Operation() {
        // TODO Auto-generated method stub
        System.out.println("颜色：蓝色");
        implementor.OperationImpl();
    }
}

调用方式：

public class Client {
    public static void main(String[] args) {
        //以这两个抽象类型(接口)声明的对象，是稳定的。根据其子类的不同，会有不同的表现。
        Implementor imple;
        Abstraction abs;
        
        //双重扩展点
        //方形+红色
        imple = new ConcreteImplementorA();//方形
        abs = new RefinedAbstractionA(imple);//将"方形"送入"红色"
        
        ////圆形+蓝色
        //imple = new ConcreteImplementorB();//圆形
        //abs = new RefinedAbstractionC(imple);//将"圆形"送入"蓝色"
                
        abs.Operation();
    }
}

执行结果：