跑腿系统开发如何实现可扩展的多业务模型设计

CREATE TABLE orders (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    order_no VARCHAR(64) NOT NULL,
    user_id BIGINT NOT NULL,
    business_type VARCHAR(32) NOT NULL,
    status INT NOT NULL,
    total_amount DECIMAL(10,2),
    create_time DATETIME,
    update_time DATETIME
);

CREATE TABLE order_ext_buy (
    order_id BIGINT,
    goods_name VARCHAR(255),
    shop_address VARCHAR(255),
    FOREIGN KEY (order_id) REFERENCES orders(id)
);

CREATE TABLE order_ext_delivery (
    order_id BIGINT,
    pickup_address VARCHAR(255),
    receiver_address VARCHAR(255),
    weight DECIMAL(8,2),
    FOREIGN KEY (order_id) REFERENCES orders(id)
);

public interface BusinessHandler {

    void validate(CreateOrderRequest request);

    BigDecimal calculatePrice(CreateOrderRequest request);

    void afterCreate(Order order);
}

@Component("BUY")
public class BuyBusinessHandler implements BusinessHandler {

    @Override
    public void validate(CreateOrderRequest request) {
        if (request.getShopAddress() == null) {
            throw new RuntimeException("商家地址不能为空");
        }
    }

    @Override
    public BigDecimal calculatePrice(CreateOrderRequest request) {
        return new BigDecimal("5.00"); // 基础跑腿费
    }

    @Override
    public void afterCreate(Order order) {
        // 保存买单扩展数据
    }
}

@Component("DELIVERY")
public class DeliveryBusinessHandler implements BusinessHandler {

    @Override
    public void validate(CreateOrderRequest request) {
        if (request.getPickupAddress() == null) {
            throw new RuntimeException("取件地址不能为空");
        }
    }

    @Override
    public BigDecimal calculatePrice(CreateOrderRequest request) {
        return new BigDecimal("8.00");
    }

    @Override
    public void afterCreate(Order order) {
        // 保存配送扩展数据
    }
}

@Service
public class BusinessFactory {

    @Autowired
    private Map<String, BusinessHandler> handlerMap;

    public BusinessHandler getHandler(String businessType) {
        return handlerMap.get(businessType);
    }
}

public Order createOrder(CreateOrderRequest request) {

    BusinessHandler handler = businessFactory.getHandler(request.getBusinessType());

    handler.validate(request);

    BigDecimal price = handler.calculatePrice(request);

    Order order = new Order();
    order.setBusinessType(request.getBusinessType());
    order.setTotalAmount(price);

    orderRepository.save(order);

    handler.afterCreate(order);

    return order;
}

CREATE TABLE pricing_rule (
    business_type VARCHAR(32),
    formula VARCHAR(255)
);

base_fee + distance * 1.2

ExpressionParser parser = new SpelExpressionParser();
Expression exp = parser.parseExpression(formula);

StandardEvaluationContext context = new StandardEvaluationContext();
context.setVariable("distance", 3.5);
context.setVariable("base_fee", 5);

BigDecimal result = exp.getValue(context, BigDecimal.class);