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登录功能实现

1. 登录页面设置

登录页面应设置为 login.jsp，并在欢迎页中指定登录页面或通过 index.jsp 转发至 login.jsp。以下是通过 index.jsp 实现的转发方式：

2. 数据库访问接口

定义 LoginDao 接口，用于获取用户登录信息：

public interface LoginDao {    User getLogin(String userCode) throws SQLException;}

3. 数据库访问实现类

实现 LoginDao 接口的 LoginDaoImpl 类：

public class LoginDaoImpl implements LoginDao {    @Override    public User getLogin(String uCode) throws SQLException {        Connection conn = BaseDao.getConn();        if (conn != null) {            try {                PreparedStatement preparedStatement = conn.prepareStatement(                    "SELECT * FROM smbms_user WHERE userCode = ?");                preparedStatement.setString(1, uCode);                ResultSet resultSet = BaseDao.executeQ(conn, preparedStatement, null, null);                if (resultSet.next()) {                    User user = new User();                    user.setId(resultSet.getInt("id"));                    user.setUserCode(resultSet.getString("userCode"));                    user.setUserName(resultSet.getString("userName"));                    user.setUserPassword(resultSet.getString("userPassword"));                    // 其他字段获取和赋值                    return user;                }            } catch (SQLException e) {                e.printStackTrace();            }            BaseDao.close(conn, preparedStatement, null);        }        return null;    }}

4. 业务逻辑接口

定义 LoginService 接口，用于处理登录业务：

public interface LoginService {    User login(String uCode, String uPassword) throws SQLException;}

5. 业务逻辑实现类

实现 LoginService 接口的 LoginServiceImpl 类：

public class LoginServiceImpl implements LoginService {    @Override    public User login(String uCode, String uPassword) throws SQLException {        LoginDao loginDao = new LoginDaoImpl();        User user = loginDao.getLogin(uCode);        return user;    }}

6. 登录Servlet实现

创建 LoginServlet 类，处理登录请求：

@WebServlet("/login.do")public class LoginServlet extends HttpServlet {    @Override    protected void service(HttpServletRequest req, HttpServletResponse resp)        throws ServletException, IOException {        String userCode = req.getParameter("userCode");        String password = req.getParameter("userPassword");        LoginService loginService = new LoginServiceImpl();        try {            User user = loginService.login(userCode, password);            if (user != null) {                HttpSession session = req.getSession();                session.setAttribute(Constants.USER_SESSION, user);                resp.sendRedirect("frame.jsp");            } else {                req.setAttribute("error", "用户名或密码错误");                req.getRequestDispatcher("login.jsp").forward(req, resp);            }        } catch (SQLException e) {            e.printStackTrace();        }    }}

7. 登出功能实现

创建 LogoutServlet 类，处理注销操作：

@WebServlet("/user/exit.do")public class LogoutServlet extends HttpServlet {    @Override    protected void service(HttpServletRequest req, HttpServletResponse resp)        throws ServletException, IOException {        HttpSession session = req.getSession();        session.removeAttribute(Constants.USER_SESSION);        resp.sendRedirect("/login.jsp");    }}

8. 登录拦截优化

创建 SysFilter 类，实现登录拦截：

@WebFilter("/jsp/*")public class SysFilter implements Filter {    @Override    public void init(FilterConfig filterConfig) throws ServletException {        // 初始化逻辑可根据需求添加    }    @Override    public void doFilter(        ServletRequest servletRequest,        ServletResponse servletResponse,        FilterChain filterChain)        throws IOException, ServletException {        HttpServletRequest request = (HttpServletRequest) servletRequest;        HttpServletResponse response = (HttpServletResponse) servletResponse;        HttpSession session = request.getSession();        User user_sess = (User) session.getAttribute(Constants.USER_SESSION);        if (user_sess == null) {            request.getRequestDispatcher("/error.jsp").forward(request, response);        } else {            filterChain.doFilter(servletRequest, servletResponse);        }    }    @Override    public void destroy() {        // 销毁逻辑可根据需求添加    }}

总结

以上实现完整地完成了登录功能的开发，涵盖了页面转发、数据库访问、业务逻辑处理以及前后端的整合。通过拦截器优化，确保未登录用户无法访问核心功能，进一步提升了系统安全性。

转载地址：http://ulgh.baihongyu.com/