类图关系如下：

结构型设计模式之 桥接模式.jpg

示例代码：

public interface IMaterial {
    void pack();
}
public class PaperBag implements IMaterial {
    @Override
    public void pack() {
        System.out.println("使用纸质包装盒打包----");
    }
}
public class PlasticBag implements IMaterial {
    @Override
    public void pack() {
        System.out.println("使用塑料材质包装----");
    }
}

public abstract class BagAbstract {
    private IMaterial material; //持有可扩展接口角色引用

    public BagAbstract(IMaterial material) {
        this.material = material;
    }

    public abstract void pick();

}
public class BigBag extends BagAbstract {
    public BigBag(IMaterial material) {
        super(material);
    }

    @Override
    public void pick() {
        System.out.println("使用大号袋子进行采摘");
    }

}
public class MidBag extends BagAbstract {
    public MidBag(IMaterial material) {
        super(material);
    }

    @Override
    public void pick() {
        System.out.println("使用中号袋子进行采摘");
    }
}
public class SmallBag extends BagAbstract {
    public SmallBag(IMaterial material) {
        super(material);
    }

    @Override
    public void pick() {
        System.out.println("使用小号袋子进行采摘");
    }
}

public class Test {

    public static void main(String[] args) {
        IMaterial material = new PaperBag(); //可以任意选择包装材质（材质可以扩展）
        BagAbstract big = new BigBag(material);//可以选择包装的规格大小
        material.pack();
        big.pick();
    }
}