jdbc.properties文件中的配置需要加上" jdbc."的前缀

在配置数据库连接信息（jdbc.properties文件）时跟着老师的编码走的，如下：

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/seckill?useUnicode=true&characterEncoding=utf8
username=root
password=464648

但是居然报错了：

### Error querying database.  Cause: org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Access denied for user 'root '@'localhost' (using password: YES))
### The error may exist in mapper/CustomerMapper.xml
### The error may involve com.zhexiang.mybatis_springmvc.model.selectCustomerByID
### The error occurred while executing a query

后来百度了一下，在以上的配置中需要写成如下形式，有哪位同学知道具体原因么？

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/seckill?useUnicode=true&characterEncoding=utf8
jdbc.username=root
jdbc.password=