使用Hibernate的最简单策略是打开一个会话(或获取当前会话)，开始事务，执行请求，提交并关闭每个操作的会话(showTableGmail, saveOrUpdateGmail).因此，您需要从DBTable()构造函数中删除所有代码，并执行类似

The simplest strategy of using Hibernate is open a session (or get current one), begin a transaction, do request, commit, and close a session for every operation (showTableGmail, saveOrUpdateGmail). So you need to delete all code from DBTable() constructor and do something like this.