写一个停车场收费系统的代码

好的，以下是一个简单的停车场收费系统的代码示例：

class ParkingLot:
    def __init__(self, capacity):
        self.capacity = capacity
        self.spots = [None] * capacity

    def park(self, vehicle):
        if None not in self.spots:
            return False
        for i in range(self.capacity):
            if self.spots[i] is None:
                self.spots[i] = vehicle
                return True

    def unpark(self, spot):
        if self.spots[spot] is None:
            return False
        self.spots[spot] = None
        return True

class Vehicle:
    def __init__(self, license):
        self.license = license

class Car(Vehicle):
    def __init__(self, license):
        super().__init__(license)
        self.fee = 5

class Truck(Vehicle):
    def __init__(self, license):
        super().__init__(license)
        self.fee = 10

class Motorbike(Vehicle):
    def __init__(self, license):
        super().__init__(license)
        self.fee = 3

class ParkingMeter:
    def __init__(self, rate):
        self.rate = rate
        self.start_time = None
        self.end_time = None

    def start(self):
        self.start_time = time.time()

    def stop(self):
        self.end_time = time.time()

    def get_duration(self):
        return self.end_time - self.start_time

    def calculate_fee(self):
        duration = self.get_duration()
        return round(duration * self.rate, 2)

parking_lot = ParkingLot(50)
meter = ParkingMeter(0.1)

while True:
    command = input("Enter command: park, unpark, or quit\n")
    if command == "park":
        license = input("Enter license plate number:\n")
        vehicle_type = input("Enter vehicle type (car, truck, or motorbike):\n")
        if vehicle_type == "car":
            vehicle = Car(license)
        elif vehicle_type == "truck":
            vehicle = Truck(license)
        elif vehicle_type == "motorbike":
            vehicle = Motorbike(license)
        else:
            print("Invalid vehicle type")
            continue
        if parking_lot.park(vehicle):
            print("Vehicle parked")
            meter.start()
        else:
            print("Parking lot full")
    elif command == "unpark":
        spot = input("Enter spot number:\n")
        if parking_lot.unpark(int(spot)):
            meter.stop()
            fee = meter.calculate_fee()
            print("Vehicle unparked. Fee: $", fee)
        else:
            print("Invalid spot number")
    elif command == "quit":
        break
    else:
        print("Invalid command")

这个代码示例包括了停车场类、车辆类、计费器类和一个简单的用户界面，可以让用户通过命令行输入来模拟停车和取车的过程。其中，计费器类使用了 Python 内置的 time 模块来计算停车时间，并根据每分钟的收费率计算出停车费用。如果需要更复杂的功能，可以根据实际需求进行修改和扩展。