每次从题库中随机挑选五道考题(这五道题不会重复)

 /**
     *司机招募 每次从题库中随机挑选五道考题(这五道题不会重复)
     * @param request
     * @param response
     */
    @RequestMapping("itemBankRandom")
    public void itemBankRandom(HttpServletRequest request, HttpServletResponse response) {
        ReturnInfo info = new ReturnInfo();
        try {
            List<ItemBank> all = itemBankService.findAll();
            List<Integer> list = new ArrayList();
            List<ItemBank> itemBankList=new ArrayList();
            for (int i = 0; i < 5; i++)
            {
                int temp = new Random().nextInt(all.size());
             //判断列表里包含 temp 这个随机数
                if (list.contains(temp))

                { --i;
             //如果是,将 i -1,即"回滚循环"
                    continue;
                }
                else{
                    list.add(temp);
                    ItemBank itemBank=itemBankService.get(String.valueOf(temp));
                    itemBankList.add(itemBank);
                }
            }
            info.setResult(true);
            info.setObj(itemBankList);
        } catch (Exception e) {
            e.printStackTrace();
        }
        this.writeJson(response, info);

    }