启动我的 SpringBoot 应用程序后，在服务器启动的几分钟内出现异常。外部没有使用任何 HikariPool 配置，Spring Boot 默认使用 HikariPool 这是我在控制台中得到的错误：
2020-02-20 03:16:23 - HikariPool-4 - Failed to validate connection
com.mysql.cj.jdbc.ConnectionImpl@4c4180c8 (No operations allowed after connection closed.).
Possibly consider using a shorter maxLifetime value.
2020-02-20 03:16:28 - HikariPool-4 - Failed to validate connection
com.mysql.cj.jdbc.ConnectionImpl@679c2f50 (No operations allowed after connection closed.).
Possibly consider using a shorter maxLifetime value.
2020-02-20 03:16:33 - HikariPool-4 - Failed to validate connection
com.mysql.cj.jdbc.ConnectionImpl@16083061 (No operations allowed after connection closed.).
Possibly consider using a shorter maxLifetime value.
2020-02-20 03:16:38 …