从Servlet+JSP+JDBC到MyBatis：重构用户CRUD操作的高效之旅

package servlet; import dao.UserDao; import entity.User; import entity.dto.UserDto; import org.apache.ibatis.session.SqlSession; import util.PageUtil; import util.SqlSessionFactoryUtil; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.util.List; @WebServlet("/userPage") public class UserPageServlet extends HttpServlet { @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { SqlSession session= SqlSessionFactoryUtil.getSessionSql(); UserDao userDao= session.getMapper(UserDao.class); String keyword= request.getParameter("keyword"); if (keyword==null){//当关键字为null时，设置为空，防止没有进行模糊查询时，sql失效 keyword=""; } String currentPage =request.getParameter("pageIndex"); if (currentPage==null){//防止第一次访问servlet时，当前页为空，设置为第一页 currentPage="1"; } int pageIndex = Integer.parseInt(currentPage); // UserDao userDao =new UserDaoImpl(); int count = userDao.selectUsersCount(); //总页数 int totalPages= PageUtil.getTotalPages(count,PageUtil.PAGE_SIZE); //防止查询越界 if (pageIndex<1){ pageIndex=1; } if (pageIndex>totalPages){ pageIndex=totalPages; } UserDto userDto =new UserDto(); userDto.setKeyword(keyword); // System.out.println(userDto.getKeyword()); userDto.setPageIndex(PageUtil.PAGE_SIZE*(pageIndex-1)); // System.out.println(userDto.getPageIndex()); userDto.setPageSize(PageUtil.PAGE_SIZE); List<User> list= userDao.selectUserListByPage(userDto); //在request作用域设置值，仅在同一个请求中有效 request.setAttribute("list",list); for (User user : list) { System.out.println(user); } request.setAttribute("keyword",keyword); request.setAttribute("pageIndex",pageIndex); request.setAttribute("totalPages",totalPages); //转发当前请求到userList.jsp request.getRequestDispatcher("/front/userList.jsp").forward(request,response); // request.getRequestDispatcher("zhezhaoceng.jsp").forward(request,response); } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { doPost(req,resp); } }