Java【代码 06】Lamda表达式将List对象中的Map对象的key全部转化为大写或者小写（去除外层循环：可用于Map对象中的key全部转化为大写或者小写

    /**
     * 将小写 key 转换为大写 key
     *
     * @param mapList 小写 key 的map
     * @return 大写 keys 的map
     */
    private List<Map<String, Object>> mapKeysToUpperCase(List<Map<String, Object>> mapList) {
        List<Map<String, Object>> returnList = new ArrayList<>(mapList.size());
        mapList.forEach(oneMap -> {
            Map<String, Object> returnMap = new HashMap<>(oneMap.size());
            // 转为小写 oneMap.forEach((key, val) -> returnMap.put(key.toLowerCase(), val));
            oneMap.forEach((key, val) -> returnMap.put(key.toUpperCase(), val));
            returnList.add(returnMap);
        });
        return returnList;
    }

# 别名无效 查询结果封装成 map 则 key 为 tablename
select table_name AS tableName from table_info
select table_name AS TABLENAME from table_info

# 别名有效 查询结果封装成 map 则 key 为 tableName
select table_name AS "tableName" from table_info