1 添加相关依赖：

implementation "mysql:mysql-connector-java:${mysqlConnectorJavaVersion}"

compile "com.baomidou:mybatis-plus-boot-starter:${mybatisPlusStarterVersion}"

mysql-connector-java包的作用：

ref: https://blog.csdn.net/Ricky_Monarch/article/details/99672787

ref: https://blog.csdn.net/weixin_43287508/article/details/86613644

图解java连接mysql：

 

 

ref: https://www.cnblogs.com/V1haoge/p/10125279.html (看起来很详细)