解决Connections could not be acquired from the underlying database!的问题

Caused by: java.sql.SQLException: Connections could not be acquired from the underlying database!

做Spring+Mybatis的项目，报错

jdbc.properies:

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/seckill
username=root
password=root

spring-dao.xml:

如果不用jdbc配置文件直接写就可以。

最后发现是username的问题，好像改个名就可以，比如：usernamex=root