报错提示：
Sat Oct 21 09:28:33 CST 2019 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.
报错翻译：
12月21日星期六09:28:33 CST 2019警告：没有服务器的身份验证建立SSL连接，不推荐。根据MySQL 5.5.45 +，+，+ 5.6.26 5.7.6要求SSL连接必须建立明确的选项默认情况下如果不设置。符合现有的应用程序不使用SSL的verifyservercertificate属性设置为“false”。你需要显式禁用SSL设置usessl = false，或设置usessl =真实提供服务器证书验证信任库。
解决方法：
在jdbc.properties配置文件中将url的内容添加一句话：useSSL=false
url=jdbc:mysql://localhost:3306/db3?useUnicode=true&characterEncoding=UTF-8&useSSL=false