如何使用Java编写CMS系统的在线支付模块

public class PaymentController {
    @PostMapping("/choosePayment")
    public String choosePayment(String paymentMethod) {
        // 根据支付方式跳转到相应的支付页面
        if(paymentMethod.equals("alipay")) {
            return "redirect:/alipayPage";
        } else if(paymentMethod.equals("wechatpay")) {
            return "redirect:/wechatpayPage";
        }
    }
}

public class OrderService {
    public void createOrder(List<CartItem> cartItems, User user) {
        // 根据购物车中的商品和用户信息生成订单，并存储到数据库中
        Order order = new Order();
        // 设置订单信息
        order.setOrderNo(UUID.randomUUID().toString());
        order.setTotalAmount(calcTotalAmount(cartItems));
        order.setUser(user);
        // 存储订单到数据库
        orderRepository.save(order);
    }
}

public class PaymentService {
    public String generatePaymentLink(Order order, String paymentMethod) {
        // 根据订单信息和支付参数生成支付链接
        String paymentLink = "";
        
        if(paymentMethod.equals("alipay")) {
            // 使用支付宝支付接口生成支付链接
            // ...
        } else if(paymentMethod.equals("wechatpay")) {
            // 使用微信支付接口生成支付链接
            // ...
        }
        
        return paymentLink;
    }
}

public class PaymentController {
    @GetMapping("/alipayPage")
    public String alipayPage(Model model, Order order) {
        String paymentLink = paymentService.generatePaymentLink(order, "alipay");
        model.addAttribute("paymentLink", paymentLink);
        return "alipayPage";
    }

    @GetMapping("/wechatpayPage")
    public String wechatpayPage(Model model, Order order) {
        String paymentLink = paymentService.generatePaymentLink(order, "wechatpay");
        model.addAttribute("paymentLink", paymentLink);
        return "wechatpayPage";
    }
}

public class PaymentController {
    @PostMapping("/payment_callback")
    public String paymentCallback(HttpServletRequest request) {
        // 解析支付回调内容
        // 更新订单状态等操作
        return "success";
    }
}