大二期末 java web.用到数据库，jdbc.myeclipse实现用户的注册，登陆 并且不能出现500错误，用户不能重复注册。当用户任意点击时也不能出现500错误(At the end of sophomore year, Java web. is used in database, jdbc.myeclipse realizes user registration and landing. And there is no 500 error. Users c