如何通过继承在java编程中创建一个交通工具抽象类，然后分别实例化为汽车、火车和飞机子类，并演示上转型过程，最后展示每个交通工具的乘坐信息？

在Java中，我们可以创建一个`Transportation`抽象类作为交通工具的基础，包含一些通用属性和方法，如`name`、`maxSpeed`等。然后为具体的交通工具如`Car`、`Train`和`Airplane`分别创建子类，实现这些抽象方法。

// 抽象类 Transportation
abstract class Transportation {
    protected String name;
    private int maxSpeed;

    public Transportation(String name, int maxSpeed) {
        this.name = name;
        this.maxSpeed = maxSpeed;
    }

    // 公共方法
    abstract void displayInfo();

    public void setMaxSpeed(int maxSpeed) {
        this.maxSpeed = maxSpeed;
    }

    // 上转型示例
    public static Transportation createVehicle(String vehicleType, String name, int maxSpeed) {
        switch (vehicleType) {
            case "Car":
                return new Car(name, maxSpeed);
            case "Train":
                return new Train(name, maxSpeed);
            case "Airplane":
                return new Airplane(name, maxSpeed);
            default:
                throw new IllegalArgumentException("Invalid vehicle type");
        }
    }

    // 重写displayInfo方法以显示交通工具信息
    protected abstract void displayConcreteInfo();
}

class Car extends Transportation {
    @Override
    protected void displayConcreteInfo() {
        System.out.println(name + " is a car with a max speed of " + maxSpeed + " km/h.");
    }
}

class Train extends Transportation {
    @Override
    protected void displayConcreteInfo() {
        System.out.println(name + " is a train with a max speed of " + maxSpeed + " km/h.");
    }
}

class Airplane extends Transportation {
    @Override
    protected void displayConcreteInfo() {
        System.out.println(name + " is an airplane with a max speed of " + maxSpeed + " km/h.");
    }
}

public class Main {
    public static void main(String[] args) {
        // 创建交通工具实例并展示乘坐信息
        Transportation car = Transportation.createVehicle("Car", "Toyota", 200);
        car.displayInfo(); // 输出：Toyota is a car with a max speed of 200 km/h.

        Transportation train = Transportation.createVehicle("Train", "Bullet Train", 300);
        train.displayInfo(); // 输出：Bullet Train is a train with a max speed of 300 km/h.

        Transportation airplane = Transportation.createVehicle("Airplane", "Boeing 747", 900);
        airplane.displayInfo(); // 输出：Boeing 747 is an airplane with a max speed of 900 km/h.
    }
}

在这个例子中，我们展示了如何通过继承`Transportation`抽象类创建具体的交通工具，并使用上转型技术统一处理它们。当我们调用`Transportation`类型的实例的`displayInfo()`方法时，实际上会执行子类的`displayConcreteInfo()`方法，实现了多态性。