浅析Java语言中状态模式的优点

//环境类
public class Car {
    private CarState carState;
    public Car(CarState carState) {
        this.carState = carState;
    }
    public void setCarState(CarState carState) {
        this.carState = carState;
    }
    public void openDoor(){
        carState.openDoor();
    }
    public void closeDoor(){
        carState.closeDoor();
    }
    public void runCar(){
        carState.runCar();
    }
}
//抽象状态类
abstract class CarState{
    public abstract void openDoor();
    public abstract void closeDoor();
    public abstract void runCar();
}
//具体状态类
class OpenState extends CarState{
    @Override
    public void openDoor() {
        System.out.println("can not open the door");
    }
    @Override
    public void closeDoor() {
        System.out.println("close the door success");
    }
    @Override
    public void runCar() {
        System.out.println("can not run the car");
    }
}
//具体状态类
class CloseState extends CarState{
    @Override
    public void openDoor() {
        System.out.println("open the door success");
    }
    @Override
    public void closeDoor() {
        System.out.println("can not close the door");
    }
    @Override
    public void runCar() {
        System.out.println("run the car success");
    }
}

public class Client {
    public static void main(String[] args) {
        CarState state = new CloseState();
        Car car = new Car(state);
        car.openDoor();
        car.setCarState(new OpenState());
        car.runCar();
    }
}