解决报错(Could not create connection to database server.)

org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory 

尝试多种方法后发现是由于mysql驱动版本太低导致。

报错，mysql版本是8.0.11，mysql-connector-java版本是5.1.31，后来把mysql-connector-java改为最新版运行成功。

<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.15</version>
        </dependency>