使用servlet实现简单用户登录

一个简单的servlet加jsp的程序，实现用户注册登陆，有完整代码加逻辑。可以实现数据库连接，比较简单。

package com.zcw.dao;

import com.zcw.vo.User;

import java.util.List;

public interface IUserDAO {
    public boolean add（User user）;
    public User login（User user）;

}

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2018-05-04 12:24  T1\
     目录           0  2018-05-04 12:42  T1\.idea\
     目录           0  2018-05-04 12:25  T1\.idea\artifacts\
     文件         635  2018-05-04 12:25  T1\.idea\artifacts\T1_war_exploded.xml
     文件         288  2018-05-04 12:24  T1\.idea\encodings.xml
     目录           0  2018-05-04 12:43  T1\.idea\inspectionProfiles\
     目录           0  2018-05-04 12:24  T1\.idea\libraries\
     文件         256  2018-05-04 12:24  T1\.idea\libraries\mysql_connector_java_5_1_40.xml
     文件         224  2018-05-03 11:19  T1\.idea\libraries\servlet_api.xml
     文件         274  2018-05-04 12:22  T1\.idea\misc.xml
     文件         244  2018-05-03 11:18  T1\.idea\modules.xml
     文件       45365  2018-05-04 12:42  T1\.idea\workspace.xml
     文件         819  2018-05-04 12:24  T1\T1.iml
     目录           0  2018-05-03 17:48  T1\out\
     目录           0  2018-05-03 17:48  T1\out\artifacts\
     目录           0  2018-05-04 12:41  T1\out\artifacts\T1_war_exploded\
     目录           0  2018-05-04 12:25  T1\out\artifacts\T1_war_exploded\WEB-INF\
     目录           0  2018-05-03 22:53  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\
     目录           0  2018-05-03 17:48  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\
     目录           0  2018-05-03 18:35  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\zcw\
     目录           0  2018-05-04 12:43  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\zcw\A\
     目录           0  2018-05-04 12:25  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\zcw\dao\
     文件         201  2018-05-04 12:25  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\zcw\dao\IUserDAO.class
     文件        2744  2018-05-04 12:25  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\zcw\dao\UserDAOimpl.class
     目录           0  2018-05-04 12:25  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\zcw\db\
     文件        1128  2018-05-04 12:25  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\zcw\db\DB.class
     目录           0  2018-05-04 12:43  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\zcw\service\
     目录           0  2018-05-04 12:25  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\zcw\vo\
     文件         936  2018-05-04 12:25  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\com\zcw\vo\User.class
     目录           0  2018-05-04 12:41  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\servlet\
     文件        2301  2018-05-04 12:41  T1\out\artifacts\T1_war_exploded\WEB-INF\classes\servlet\UserLoginServlet.class
............此处省略49个文件信息