servlet+jsp练手小项目

package com.zyh.oa.servlet; import com.mysql.cj.protocol.Resultset; import com.zyh.oa.javabean.User; import com.zyh.oa.utils.DBUtils; import jakarta.servlet.Registration; import jakarta.servlet.ServletException; import jakarta.servlet.annotation.WebServlet; import jakarta.servlet.http.HttpServlet; import jakarta.servlet.http.HttpServletRequest; import jakarta.servlet.http.HttpServletResponse; import java.io.IOException; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; /** * @author zengyihong * @create 2022--03--30 20:05 */ @WebServlet({"/dept/list","/dept/detail","/dept/add","/dept/save","/dept/delete"}) public class DeptServlet extends HttpServlet { @Override protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //模板方法设计模式 /** * 我们可以获取servlet的路径，根据路径来执行相应的方法 */ String servletPath = request.getServletPath(); if ("/dept/list".equals(servletPath)){ doList(request,response); }else if ("/dept/detail".equals(servletPath)){ doDetail(request,response); }else if ("/dept/add".equals(servletPath)){ doAdd(request,response); }else if ("/dept/save".equals(servletPath)){ doSave(request,response); }else if ("/dept/delete".equals(servletPath)){ doMyDelete(request,response); } } /** * 根据传入的部门编号来删除数据 * @param request * @param response */ private void doMyDelete(HttpServletRequest request, HttpServletResponse response) throws IOException { String deptno = request.getParameter("deptno"); Connection conn=null; PreparedStatement ps=null; ResultSet rs=null; int cnt=0; try { conn=DBUtils.getConnection(); String sql="delete from dept where deptno=?"; ps = conn.prepareStatement(sql); ps.setString(1,deptno); cnt = ps.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); } finally { DBUtils.close(conn,ps,rs); } if (cnt >0){ response.sendRedirect(request.getContextPath()+"/dept/list"); } } /** * 把修改后的数据保存到数据库 * @param request * @param response * @throws IOException */ private void doSave(HttpServletRequest request, HttpServletResponse response) throws IOException { //根据获取的参数来修改数据库中的记录 String deptno = request.getParameter("deptno"); String dname = request.getParameter("dname"); String loc = request.getParameter("loc"); Connection conn=null; PreparedStatement ps=null; ResultSet rs=null; int cnt=0; try { conn=DBUtils.getConnection(); String sql="update dept set dname=? ,loc=? where deptno=?"; ps = conn.prepareStatement(sql); ps.setString(1,dname); ps.setString(2,loc); ps.setString(3,deptno); cnt = ps.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); } finally { DBUtils.close(conn,ps,rs); } //修改成功后，回到列表页面 if (cnt > 0){ response.sendRedirect(request.getContextPath()+"/dept/list"); } } /** * 新增部门 * @param request * @param response */ private void doAdd(HttpServletRequest request, HttpServletResponse response) throws IOException { /** * 根据获取的参数，来存入数据库中 */ String deptno = request.getParameter("deptno"); String dname = request.getParameter("dname"); String loc = request.getParameter("loc"); Connection conn=null; PreparedStatement ps=null; ResultSet rs=null; int cnt=0; try { conn=DBUtils.getConnection(); String sql="insert into dept(deptno,dname,loc) values(?,?,?)"; ps = conn.prepareStatement(sql); ps.setString(1,deptno); ps.setString(2,dname); ps.setString(3,loc); cnt = ps.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); } finally { DBUtils.close(conn,ps,rs); } if (cnt>0){ //说明保存成功，跳转到部门列表页面 response.sendRedirect(request.getContextPath()+"/dept/list"); } } /** * 部门详情功能，点击详情，根据部门编号返回相应的数据 * @param request * @param response */ private void doDetail(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { /** * 首先获取前端浏览器传过来的部门编号信息 * 根据这个信息来查询对应的信息 * 然后返回给详情页面进行展示 */ String deptno = request.getParameter("deptno"); Connection conn=null; PreparedStatement ps=null; ResultSet rs=null; List<User> list=new ArrayList<>(); try { conn=DBUtils.getConnection(); String sql="select dname,loc from dept where deptno=?"; ps=conn.prepareStatement(sql); ps.setString(1,deptno); rs=ps.executeQuery(); //查到数据，返回 while (rs.next()){ User user=new User(); user.setDeptno(deptno); user.setDname(rs.getString(1)); user.setLoc(rs.getString(2)); list.add(user); } } catch (SQLException e) { e.printStackTrace(); } finally { DBUtils.close(conn,ps,rs); } //把数据给JSP // 使用转发，因为需要取数据 //因为详情和修改的第一步它们执行的servlet是一样的，所以我们可以根据参数的值来判断到底是详情还是修改 request.setAttribute("list",list); String f = request.getParameter("f"); if ("detail".equals(f)){ request.getRequestDispatcher("/detail.jsp").forward(request,response); }else if ("edit".equals(f)){ //走修改页面 request.getRequestDispatcher("/edit.jsp").forward(request,response); } } /** * 展示部门列表页面 * @param request * @param response * @throws ServletException * @throws IOException */ private void doList(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { /** * 使用JDBC连接数据库，查询表中数据 */ Connection conn=null; PreparedStatement ps=null; ResultSet rs=null; List<User> list=new ArrayList<>(); try { conn= DBUtils.getConnection(); String sql="select deptno,dname,loc from dept"; ps=conn.prepareStatement(sql); rs = ps.executeQuery(); while (rs.next()){ String deptno = rs.getString("deptno"); String dname = rs.getString("dname"); String loc = rs.getString("loc"); User user=new User(deptno,dname,loc); list.add(user); } } catch (SQLException