使用JSP+Servlet+JDBC技术 三层架构 对atm库中的atm_user表进行 1，登录 2，列表（user_name条件模糊查询） 3，删除

好的，我可以为您提供一个简单的示例代码。

首先，我们需要建立一个三层架构的项目，包含 DAO 层、Service 层和 Controller 层。

在 DAO 层中，我们可以定义一个 UserDao 接口和一个 UserDaoImpl 类来实现该接口。在 UserDao 接口中，我们可以定义登录、列表和删除等操作的方法。在 UserDaoImpl 类中，我们可以使用 JDBC 技术来实现这些方法。

在 Service 层中，我们可以定义一个 UserService 接口和一个 UserServiceImpl 类来实现该接口。在 UserServiceImpl 类中，我们可以调用 UserDaoImpl 中的方法，并对数据进行一些处理和封装。

在 Controller 层中，我们可以定义一个 UserServlet 类来处理用户请求。在 UserServlet 类中，我们可以调用 UserServiceImpl 中的方法，并将结果发送给用户界面。

下面是示例代码：

UserDao.java

public interface UserDao {
    boolean login(String username, String password) throws SQLException;
    List<User> getUserList(String username) throws SQLException;
    boolean deleteUser(int id) throws SQLException;
}

UserDaoImpl.java

public class UserDaoImpl implements UserDao {
    private Connection conn = null;
    private PreparedStatement pstmt = null;

    public UserDaoImpl(Connection conn) {
        this.conn = conn;
    }

    @Override
    public boolean login(String username, String password) throws SQLException {
        String sql = "SELECT * FROM atm_user WHERE user_name=? AND user_password=?";
        pstmt = conn.prepareStatement(sql);
        pstmt.setString(1, username);
        pstmt.setString(2, password);
        ResultSet rs = pstmt.executeQuery();
        if (rs.next()) {
            return true;
        } else {
            return false;
        }
    }

    @Override
    public List<User> getUserList(String username) throws SQLException {
        List<User> userList = new ArrayList<>();
        String sql = "SELECT * FROM atm_user WHERE user_name LIKE ?";
        pstmt = conn.prepareStatement(sql);
        pstmt.setString(1, "%" + username + "%");
        ResultSet rs = pstmt.executeQuery();
        while (rs.next()) {
            User user = new User();
            user.setId(rs.getInt("user_id"));
            user.setUsername(rs.getString("user_name"));
            user.setPassword(rs.getString("user_password"));
            user.setBalance(rs.getDouble("user_balance"));
            userList.add(user);
        }
        return userList;
    }

    @Override
    public boolean deleteUser(int id) throws SQLException {
        String sql = "DELETE FROM atm_user WHERE user_id=?";
        pstmt = conn.prepareStatement(sql);
        pstmt.setInt(1, id);
        int result = pstmt.executeUpdate();
        if (result > 0) {
            return true;
        } else {
            return false;
        }
    }
}

UserService.java

public interface UserService {
    boolean login(String username, String password) throws SQLException;
    List<User> getUserList(String username) throws SQLException;
    boolean deleteUser(int id) throws SQLException;
}

UserServiceImpl.java

public class UserServiceImpl implements UserService {
    private UserDao userDao;

    public UserServiceImpl(UserDao userDao) {
        this.userDao = userDao;
    }

    @Override
    public boolean login(String username, String password) throws SQLException {
        return userDao.login(username, password);
    }

    @Override
    public List<User> getUserList(String username) throws SQLException {
        return userDao.getUserList(username);
    }

    @Override
    public boolean deleteUser(int id) throws SQLException {
        return userDao.deleteUser(id);
    }
}

UserServlet.java

public class UserServlet extends HttpServlet {
    private UserService userService;

    public UserServlet() {
        super();
        userDao = new UserDaoImpl(DBUtil.getConnection());
        userService = new UserServiceImpl(userDao);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String action = request.getParameter("action");
        if (action.equals("login")) {
            String username = request.getParameter("username");
            String password = request.getParameter("password");
            try {
                if (userService.login(username, password)) {
                    response.sendRedirect("userList.jsp");
                } else {
                    response.sendRedirect("login.jsp");
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        } else if (action.equals("list")) {
            String username = request.getParameter("username");
            try {
                List<User> userList = userService.getUserList(username);
                request.setAttribute("userList", userList);
                RequestDispatcher rd = request.getRequestDispatcher("userList.jsp");
                rd.forward(request, response);
            } catch (SQLException e) {
                e.printStackTrace();
            }
        } else if (action.equals("delete")) {
            int id = Integer.parseInt(request.getParameter("id"));
            try {
                userService.deleteUser(id);
                response.sendRedirect("userList.jsp");
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

以上代码仅供参考，具体的实现还需要您根据自己的需求进行修改。希望对您有所帮助！