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 i

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。