springmvc+Mybatis+c3p0提示 Connections could not be acquired from the underlying database!错误

提示 Connections could not be acquired from the underlying database! 主要问题出在数据库上

1 数据库的username写错了 或者你在dp.properties文件里面不可以单独写username 会发生冲突 要写jdbc.username=XXXX

2 jdbc.driverClassName=com.mysql.jjdbc.Driver 这里面的Driver 要大写

3 就是jdbc.jdbcUrl=jdbc:mysql://localhost:3306/student?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8 这行一定要设置时区（&serverTimezone=GMT%2B8）