使用MySQL数据库时出现如下错误：
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.
网上查了查，是当前版本的MySQL要求使用SSL，做出如下修改即可：
将
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/jsp_db","root","123456");
改成
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/jsp_db?useSSL=false","root","123456");
问题解决。