11.4总结

@WebServlet("/login")
public class LoginServlet extends HttpServlet {
private UserService userService = new UserServiceImpl();

@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    request.setCharacterEncoding("UTF-8");
    String userId = request.getParameter("userId");
    String password = request.getParameter("password");
    String userType = request.getParameter("userType");

    // 验证用户身份
    Object user = userService.login(userId, password, userType);
    if (user != null) {
        // 存储用户信息到Session
        request.getSession().setAttribute("user", user);
        request.getSession().setAttribute("userType", userType);
        // 跳转对应功能页
        if ("admin".equals(userType)) {
            response.sendRedirect(request.getContextPath() + "/admin/index.jsp");
        } else if ("teacher".equals(userType)) {
            response.sendRedirect(request.getContextPath() + "/teacher/index.jsp");
        } else if ("student".equals(userType)) {
            response.sendRedirect(request.getContextPath() + "/student/index.jsp");
        }
    } else {
        request.setAttribute("errorMsg", "账号或密码错误");
        request.getRequestDispatcher("/login.jsp").forward(request, response);
    }
}

}