关键点:识别哪些提交是同样的提交

解决方法：在页面设置token，利用redis事务的原子性。比如，在trade页面，点击提交订单，会生成一个token嵌入在页面中。点击结算时会验证token，解决重复提交的问题。

代码:

  • controller"trade"

    @GetMapping("trade")
  @LoginRequire
  public String trade(HttpServletRequest request){
      String userId =(String)request.getAttribute("userId");
      //  用户地址  列表
      List<UserAddress> userAddressList = userService.getUserAddressList(userId);

      request.setAttribute("userAddressList",userAddressList);

      //  用户需要结账的商品清单
      List<CartInfo> checkedCartList = cartService.getCheckedCartList(userId);
      BigDecimal totalAmount = new BigDecimal("0");
      for (CartInfo cartInfo : checkedCartList) {
          BigDecimal cartInfoAmount = cartInfo.getSkuPrice().multiply(new BigDecimal(cartInfo.getSkuNum()));
          totalAmount= totalAmount.add(cartInfoAmount);
      }

      String token = orderService.genToken(userId);//生成token

      request.setAttribute("tradeNo",token);//request请求后面放token

      request.setAttribute("checkedCartList",checkedCartList);

      request.setAttribute("totalAmount",totalAmount);

      return  "trade";
  }

    • 生成token的方法

      @Override
public String genToken(String userId) {
    //token  type   String  key   user:10201:trade_code  value token
    String token = UUID.randomUUID().toString();
    String tokenKey="user:"+userId+":trade_code";
    Jedis jedis = redisUtil.getJedis();
    jedis.setex(tokenKey,10*60,token);
    jedis.close();

    return token;
}

  • controller"submitOrder"

    @PostMapping("submitOrder")
  @LoginRequire
  public String submitOrder(OrderInfo orderInfo,HttpServletRequest request){
      String userId = (String) request.getAttribute("userId");

      String tradeNo = request.getParameter("tradeNo");//拿到token

      boolean isEnableToken = orderService.verifyToken(userId, tradeNo);//验证token
      if(!isEnableToken){
          request.setAttribute("errMsg","页面已失效，请重新结算！");
          return  "tradeFail";
      }

      }

      String orderId = orderService.saveOrder(orderInfo);

      // 删除购物车信息
      //  xxxx
      return "redirect://payment.gmall.com/index?orderId="+orderId;
  }

    • 验证token service

      @Override
    public boolean verifyToken(String userId, String token) {
        String tokenKey="user:"+userId+":trade_code";
        Jedis jedis = redisUtil.getJedis();
        String tokenExists = jedis.get(tokenKey);
        jedis.watch(tokenKey);//监控tokenkey
        Transaction transaction = jedis.multi();//开启事务
        if(tokenExists!=null&&tokenExists.equals(token)){
            transaction.del(tokenKey);//事务的删除，会在queue里面
        }
        List<Object> list = transaction.exec();//事务的提交，成功返回1，不成功会不进行任何操作，返回nill
        if(list!=null&&list.size()>0&&(Long)list.get(0)==1L){
            return true;
        }else{
            return false;
        }
    }