// 下單
@PostMapping(value = "/submitOrder")
public String submitOrder(OrderSubmitVo vo, Model model, RedirectAttributes attributes) {

    try {
        SubmitOrderResponseVo responseVo = orderService.submitOrder(vo);
        //下單成功來到支付選擇頁
        //下單失敗回到訂單確認頁重新確定訂單信息
        if (responseVo.getCode() == 0) {
            //成功
            model.addAttribute("submitOrderResp", responseVo);
            return "pay";
        } else {
            String msg = "下單失敗";
            switch (responseVo.getCode()) {
                case 1:
                    msg += "令牌訂單信息過期，請刷新再次提交";
                    break;
                case 2:
                    msg += "訂單商品價格發生變化，請確認后再次提交";
                    break;
                case 3:
                    msg += "庫存鎖定失敗，商品庫存不足";
                    break;
            }
            attributes.addFlashAttribute("msg", msg);
            return "redirect:http://order.mall.com/toTrade";
        }
    } catch (Exception e) {
        if (e instanceof NoStockException) {
            String message = ((NoStockException) e).getMessage();
            attributes.addFlashAttribute("msg", message);
        }
        return "redirect:http://order.mall.com/toTrade";
    }
}

/**
 * 提交訂單
 *
 * @param vo
 * @return
 */
@Transactional
@Override
public SubmitOrderResponseVo submitOrder(OrderSubmitVo vo) {

    confirmVoThreadLocal.set(vo);

    // 下單後準備返回的結果
    SubmitOrderResponseVo responseVo = new SubmitOrderResponseVo();
    responseVo.setCode(0); // 預設返回0是成功
    // 獲取當前用戶登入的信息
    MemberResponseTo memberResponseTo = LoginUserInterceptor.loginUser.get();
    // 驗證令牌是否合法，令牌的對比和刪除必須保證原子性，LUA腳本
    String script = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return " +
            "0 end";
    // 拿前端傳來的token
    String orderToken = vo.getOrderToken();
    // 通過腳本原子驗證令牌和刪除令牌
    Long result = redisTemplate.execute(new DefaultRedisScript<Long>(script, Long.class),
            Arrays.asList(USER_ORDER_TOKEN_PREFIX + memberResponseTo.getId()),
            orderToken);
    // 若令牌驗證失敗，注意腳本0是失敗，跟前面SubmitOrderResponseVo 0=成功相反
    if (result == 0L) {
        responseVo.setCode(1);
        return responseVo;
    } else {
        // 令牌驗證成功，創建、下訂單、驗令牌、驗價格、鎖定庫存
        // 1、創建訂單、訂單項等信息
        OrderCreateTo order = createOrder();
        // 2、驗證價格
        BigDecimal payAmount = order.getOrder().getPayAmount();
        BigDecimal payPrice = vo.getPayPrice();

        if (Math.abs(payAmount.subtract(payPrice).doubleValue()) < 0.01) {
            // 金額對比，保存
            saveOrder(order);

            // 4、庫存鎖定,只要有異常，回滾訂單數據
            // 訂單號、所有訂單項信息(skuId,skuNum,skuName)
            WareSkuLockTo lockVo = new WareSkuLockTo();
            lockVo.setOrderSn(order.getOrder().getOrderSn());

            // 獲取出要鎖定的商品數據信息【order裡面存儲的是Entity】
            List<OrderItemTo> orderItemTos = order.getOrderItems().stream().map((item) -> {
                OrderItemTo orderItemTo = new OrderItemTo();
                orderItemTo.setSkuId(item.getSkuId());
                orderItemTo.setCount(item.getSkuQuantity());
                orderItemTo.setTitle(item.getSkuName());
                return orderItemTo;
            }).collect(Collectors.toList());
            lockVo.setLocks(orderItemTos);

            // 出現的問題：扣減庫存成功了，但是由於網絡原因超時，出現異常，導致訂單事務回滾，庫存事務不回滾(解決方案：seata)
            // 為了保證高併發，不推薦使用seata，因為是加鎖，并行化，提升不了效率,可以發消息給庫存服務
            R r = wareFeignService.orderLockStock(lockVo);
            if (r.getCode() == 0) {
                // 鎖定成功
                responseVo.setOrder(order.getOrder());
                //int i = 10/0;
                // 訂單創建成功，發送消息給MQ
                rabbitTemplate.convertAndSend("order-event-exchange", "order.create.order", order.getOrder());
                // 刪除購物車裡的數據
                redisTemplate.delete(CART_PREFIX + memberResponseTo.getId());
                return responseVo;
            } else {
                //鎖定失敗
                String msg = (String) r.get("msg");
                throw new NoStockException(msg);
                // responseVo.setCode(3);
                // return responseVo;
            }
        } else {
            responseVo.setCode(2);
            return responseVo;
        }
    }
}

// 修改事務隔離級別
@Transactional(isolation = Isolation.REPEATABLE READ)

// 修改傳播級別
@Transactional(propagation = Propagation.REQUIRED)

// 設定超時
@Transactional(timeout = 30)

案例：b、c與a方法是否共用一個事務
@Transactional(timeout=30)
public void a() {
	b();// a事務傳播給了b事務，並且b事務的設置失效
	c();// c單獨創建一個新事務
}

@Transactional(propagation = Propagation.REQUIRED, timeout=2)
public void b() {
}

@Transactional(propagation = Propagation.REQUIRES_NEW)
public void c() {
}