<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.32</version>
</dependency>

jdbc:mysql://localhost:3306/xxx?useUnicode=true&characterEncoding=UTF8

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.11</version>
</dependency>

jdbc:mysql://127.0.0.1:3306/xxx?useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8

1.https://zhuanlan.zhihu.com/p/433040834
2.https://www.bilibili.com/read/cv18302858

1.Tomcat version XX only supports J2EE 1.2, 1.3, 1.4, and Java EE 5 and 6 Web
解决：https://blog.csdn.net/P_ning/article/details/106075627
2.Could not initialize class org.apache.maven.plugin.war.util.WebappStructureSerializer
解决：https://blog.csdn.net/weixin_45611051/article/details/118712494