解决方法：
只需在 ApplicationTests 类中注释掉以下内容：
@SpringBootTest
class DemoApplicationTests {
// @Test
// void contextLoads() {
// }
}
Could not transfer artifact mysql:mysql-connector-java:pom:>5.1.9 from/to aliyun (https://maven.aliyun.com/repository/public)
推荐方法2
Download MySQL Connector/J for Mac | MacUpdate
右键项目名字--Open module setting模块设置--Libraries--点加号--选择java--选择自己的mysql- connector-java.jar--ok
https://mvnrepository.com/artifact/com.mysql/mysql-connector-j/8.0.31
<!-- 正确的
https://mvnrepository.com/artifact/com.mysql/mysql-connector-j -->
<dependency>
<groupId>com.mysql</groupId>
<artifactId>mysql-connector-j</artifactId>
<version>8.0.31</version>
</dependency>
我写的是
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<!-- <version>8.0.29</version>-->
</dependency>
还有的写的是,这个真是写的五花八门
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>