1、报错如下：

2020-04-22 21:27:46.931  INFO 11468 --- [ MQTT Call: aaa] com.alibaba.druid.pool.DruidDataSource   : {dataSource-1} inited

Wed Apr 22 21:27:46 CST 2020 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.

2、报错原因是MySQL在高版本需要指明是否进行SSL连接：

3、解决方式：

1）、在配置的数据源url后追加如下属性,问题解决。

?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone =Asia/Shanghai

2）、旧的数据源配置如下：

spring:
  datasource:
    #   数据源基本配置
    username: 123456
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/restful_crud
    type: com.alibaba.druid.pool.DruidDataSource

3）修改后的数据源配置如下：

spring:
  datasource:
    #   数据源基本配置
    username: 123456
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/restful_crud?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone =Asia/Shanghai
    type: com.alibaba.druid.pool.DruidDataSource

4、常用的Mysql JDBC Url参数说明