使用java 编写出 发放商户优惠卷代码 通过和停车场系统完成优惠对接, 将停车场优惠券实现纯电子化. 无论用户移动支付或现金支付, 停车场系统均可读取到本次停车关联的停车优惠并自动抵扣停车费.

以下是一个简单的Java代码示例，用于实现商户发放优惠券并与停车场系统对接：

public class Coupon {
    private String couponCode;
    private double discountAmount;
    private Date expirationDate;

    public Coupon(String couponCode, double discountAmount, Date expirationDate) {
        this.couponCode = couponCode;
        this.discountAmount = discountAmount;
        this.expirationDate = expirationDate;
    }

    public String getCouponCode() {
        return couponCode;
    }

    public double getDiscountAmount() {
        return discountAmount;
    }

    public Date getExpirationDate() {
        return expirationDate;
    }
}

public class Merchant {
    private String merchantId;

    public Merchant(String merchantId) {
        this.merchantId = merchantId;
    }

    public void issueCoupon(double discountAmount, Date expirationDate) {
        String couponCode = generateCouponCode();
        Coupon coupon = new Coupon(couponCode, discountAmount, expirationDate);
        ParkingLotSystem.addCoupon(coupon);
    }

    private String generateCouponCode() {
        // 生成唯一的优惠券码
        return UUID.randomUUID().toString();
    }
}

public class ParkingLotSystem {
    private static List<Coupon> coupons = new ArrayList<>();

    public static void addCoupon(Coupon coupon) {
        coupons.add(coupon);
    }

    public static Coupon getCoupon(String couponCode) {
        for (Coupon coupon : coupons) {
            if (coupon.getCouponCode().equals(couponCode)) {
                return coupon;
            }
        }
        return null;
    }

    public static double applyCoupon(String couponCode, double parkingFee) {
        Coupon coupon = getCoupon(couponCode);
        if (coupon != null && coupon.getExpirationDate().after(new Date())) {
            double discountAmount = coupon.getDiscountAmount();
            return parkingFee - discountAmount;
        }
        return parkingFee;
    }
}

使用该代码，商户可以通过调用`Merchant.issueCoupon()`方法来发放优惠券。停车场系统可以调用`ParkingLotSystem.applyCoupon()`方法来检查是否有可用优惠券并自动抵扣停车费。优惠券信息会被保存在静态变量`ParkingLotSystem.coupons`中，以便停车场系统可以访问它。