记得在tomcat添加jdbc包!!
https://blog.youkuaiyun.com/Link_Ray/article/details/83149160 配置
https://blog.youkuaiyun.com/qq736238785/article/details/62248316 操作数据库
ResultSet rs;
rs.next()光标移到下一个。
request.getSession(true):若存在会话则返回该会话,否则新建一个会话。
request.getSession(false):若存在会话则返回该会话,否则返回NULL
getContextPath()https://blog.youkuaiyun.com/yilaguandemei/article/details/79601645
Java filter中的chain.doFilter详解
https://blog.youkuaiyun.com/haofengjiao/article/details/70186381