解决Mysql8 报错：ERROR 1193 (HY000): Unknown system variable 'tx_isolation'

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

Wed May 09 16:25:23 CST 2018 WARN: Establishing SSL connection without server’s identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn’t set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to ‘false’. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

原因：是因为系统安装的数据库版本太高，而项目中导入的jdbc 的jar包版本太低，两者不一致所导致的

解决方法：
(1)在pom.xml文件中将MySQL Connector / J版本升级为8：

  <!-- MySQL Connector / J是MySQL的官方JDBC驱动程序。 -->
   <dependency>
               <groupId>mysql</groupId>
               <artifactId>mysql-connector-java</artifactId>
               <version>8.0.15</version> //这里使用自己数据库版本   
   </dependency>

例如在application.yml中：

			datasource:
                url: jdbc:mysql://127.0.0.1:3306/数据库名?useSSL=true&serverTimezone=GMT&useUnicode=true&characterEncoding=utf8
                username: root
                password: ****
                driver: com.mysql.cj.jdbc.Driver