Druid连接Oracle数据库，连接失效导致SQL无法执行

原始配置：

type: com.alibaba.druid.pool.DruidDataSource
druid:
  initial-size: 5
  max-active: 25
  min-idle: 5
  max-wait: 10000
  testWhileIdle: true
  testOnBorrow: false
  testOnReturn: false
  timeBetweenEvictionRunsMillis: 2000
  minEvictableIdleTimeMillis: 600000
  maxEvictableIdleTimeMillis: 900000
  validationQuery: SELECT 1 FROM DUAL

修改后配置：增加keep-alive: true即可

type: com.alibaba.druid.pool.DruidDataSource
druid:
  initial-size: 5
  max-active: 25
  min-idle: 5
  max-wait: 10000
  testWhileIdle: true
  testOnBorrow: false
  testOnReturn: false
  timeBetweenEvictionRunsMillis: 2000
  minEvictableIdleTimeMillis: 600000
  maxEvictableIdleTimeMillis: 900000
  validationQuery: SELECT 1 FROM DUAL
  keep-alive: true

需要升级Druid版本到1.1.16之后，大于1.1.16版本，我升级到了1.1.17

https://mvnrepository.com/artifact/com.alibaba/druid-spring-boot-starter

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.17</version>
</dependency>

keep-alive配置建议参考：https://github.com/alibaba/druid/wiki/DruidDataSource%E9%85%8D%E7%BD%AE