Java链接数据库---出现的问题

1.

链接返回结果报警告：

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.

不建议在没有服务器身份验证的情况下建立SSL连接。根据MySQL 5.5.45+、5.6.26+和5.7.6+的要求，
如果未设置显式选项，则默认情况下必须建立SSL连接。为了符合不使用SSL的现有应用程序，
verifyServerCertificate属性设置为“false”。您需要通过设置useSSL=false显式禁用SSL，
或者设置useSSL=true并为服务器证书验证提供信任存储。

 在代码url后面加上?useUnicode=true&characterEncoding=utf-8&useSSL=false

static final String DB_URL = "jdbc:mysql://localhost:3306/a_test2?useUnicode=true&characterEncoding=utf-8&useSSL=false";

---2020-04-21