解决java.sql.SQLException: Failed to validate a newly established connection.

application.yml或application.properties数据库配置文件中配置问题,参考下面例子：

spring:
  datasource:
      type: com.alibaba.druid.pool.DruidDataSource
      url: jdbc:mysql://127.0.0.1:3306/test?characterEncoding=utf8
      username: root
      password: root
      driver-class-name: com.mysql.jdbc.Driver
      filters: stat
      maxActive: 20
      initialSize: 1
      maxWait: 60000
      minIdle: 1
      timeBetweenEvictionRunsMillis: 60000
      minEvictableIdleTimeMillis: 300000
      validationQuery: select 1
      testWhileIdle: true
      testOnBorrow: false
      testOnReturn: false
      poolPreparedStatements: true
      maxOpenPreparedStatements: 20
  jpa:
    properties:
      hibernate:
        show_sql: true
        format_sql: true
        physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl

其中validationQuery: select 1和physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl是重点。

另外：配置validationQuery的时候需注意，数据库不同配置的validationQuery值也不同。

validationQuery是用来验证数据库连接的查询语句，这个查询语句必须是至少返回一条结果的SELECT语句。每种数据库都有各自的验证语句，下表中从网上收集了几种常见数据库的validationQuery。

数据库	validationQuery
Oracle	select 1 from dual
MySQL	select 1
Microsoft SQL Server	select 1
DB2	select 1 from sysibm.sysdummy1
SQLite	select 1
HSQLDB	select 1 from INFORMATION_SCHEMA.SYSTEM_USERS
postgresql	select version()
ingres	select 1
Apache Derby	select 1
H2	select 1
Informix	select count(*) from systables