以前使用的是​​5.1.31​​​的​​mysql​​​驱动，后面使用​​Spring Boot​​​默认的​​mysql​​驱动，启动就报错了：

Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

按照提示，把​​application.yml​​改成如下：

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver # 之前是com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/kaven
    username: kaven
    password: 015036
  jpa:
    hibernate:
      ddl-auto: update #更新
    show-sql: true

还是报错：

java.sql.SQLException: The server time zone value 'Öйú±ê׼ʱ¼ä' is unrecognized or represents more than one time zone. You must configure either the server or JDBC driver (via the serverTimezone configuration property) to use a more specifc time zone value if you want to utilize time zone support.
  at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) ~[mysql-connector-java-8.0.13.jar:8.0.13]
  at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.13.jar:8.0.13]
  at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89) ~[mysql-connector-java-8.0.13.jar:8.0.13]
  at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63) ~[mysql-connector-java-8.0.13.jar:8.0.13]
  at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73) ~[mysql-connector-java-8.0.13.jar:8.0.13]
  at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:76) ~[mysql-connector-java-8.0.13.jar:8.0.13]

提示需要配置​​serverTimezone​​，因为本地服务器的时区值是未被认可或者表示多个时区。

修改​​application.yml​​：

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver 
    url: jdbc:mysql://localhost:3306/kaven?serverTimezone=GMT
    username: kaven
    password: 015036
  jpa:
    hibernate:
      ddl-auto: update #更新
    show-sql: true

项目启动成功。以下​​serverTimezone​​配置在博主这边都能启动成功。

serverTimezone=GMT%2B8
serverTimezone=GMT
serverTimezone=Asia/Shanghai

如果还是报错，检查​​Mysql​​​版本是否匹配​​mysql​​驱动版本。