桥接模式可以取代多层继承结构，可以在2个纬度中任意扩展一个纬度，符合开闭原则

package Bridge;

public interface brand {
    void sale();
}

class lenovo implements brand{

    public void sale() {
        System.out.println("销售联想电脑");
    }
}
class dell implements brand{

    public void sale() {
        System.out.println("销售戴尔电脑");
    }
}


package Bridge;

public class computer {
    protected brand brand;

   public computer(brand brand) {
        this.brand =brand;
    }
    public void sale(){
       brand.sale();
    }
}

class desktop extends computer{
    public desktop(brand b){
        super(b);
    }

    @Override
    public void sale() {
        super.sale();
        System.out.println("销售台式机");
    }
}
class laptop extends computer{
    public laptop(brand b){
        super(b);
    }

    @Override
    public void sale() {
        super.sale();
        System.out.println("销售笔记本");
    }
}

package Bridge;

public class client {
    public static void main(String[] args) {
        computer c=new laptop(new lenovo());
        c.sale();
    }
}

运行结果：

类图