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javaEE14（网站第9章常用开发组件课后题第4题）

发布时间：2026-05-17 22:03:39 浏览量：0

StudentDao：

package dao;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.util.ArrayList;import java.util.List;import util.JdbcUtil;import entity.Student;public class StudentDao {   //�����ݿ�������û���¼�ķ���add()   public void add(Student student) throws Exception{        Connection conn = null;        PreparedStatement ps = null;        try {               conn = JdbcUtil.getConnection();               String sql = "insert into student2  values (null,?,?,?,?) ";               ps = conn.prepareStatement(sql);               ps.setString(1, student.getSno());               ps.setString(2,student.getSname());               ps.setString(3,student.getSex());               ps.setString(4,student.getPhoto());               ps.executeUpdate();        }finally {JdbcUtil.free(null,ps, conn);}   }   //�޸����ݿ��û���¼�ķ���update()   public void update(Student student) throws Exception{       Connection conn = null;       PreparedStatement ps = null;       try {              conn = JdbcUtil.getConnection();              String sql = "update student2 set sno=?,sname=?,sex=?,photo=? where id=? ";              ps = conn.prepareStatement(sql);              ps.setString(1,student.getSno());              ps.setString(2,student.getSname());              ps.setString(3, student.getSex());              ps.setString(4, student.getPhoto());              ps.setInt(5, student.getId());              ps.executeUpdate();       }finally {JdbcUtil.free(null,ps, conn);}   }   //ɾ�����ݿ��û���¼�ķ���delete()   public void delete(int id) throws Exception{        Connection conn = null;        PreparedStatement ps = null;        try {              conn = JdbcUtil.getConnection();              String sql = "delete from student2 where id=?";              ps = conn.prepareStatement(sql);              ps.setInt(1,id);              ps.executeUpdate();       }finally {JdbcUtil.free( null,ps, conn);}   }   //����id��ѯ�û��ķ���findStudentById()   public Student findStudentById(int id) throws Exception{       Connection conn = null;       PreparedStatement ps = null;       ResultSet rs = null;       Student student=null;       try {              conn = JdbcUtil.getConnection();              String sql = "select * from student2 where id=? ";              ps = conn.prepareStatement(sql);              ps.setInt(1, id);              rs=ps.executeQuery();              if(rs.next()){                 student=new Student();                 student.setId(rs.getInt(1));                 student.setSno(rs.getString(2));                 student.setSname(rs.getString(3));                 student.setSex(rs.getString(4));              }       }finally {JdbcUtil.free(rs, ps, conn);}       return student;   }   //��ѯȫ���û��ķ���QueryAll()   public List query() throws Exception{       Connection conn = null;       PreparedStatement ps = null;       ResultSet rs = null;       List studentList=new ArrayList();       try {              conn = JdbcUtil.getConnection();              String sql = "select * from student2 ";              ps=conn.prepareStatement(sql);              rs=ps.executeQuery();              while(rs.next()){                 Student student=new Student();                 student.setId(rs.getInt(1));                 student.setSno(rs.getString(2));                 student.setSname(rs.getString(3));                 student.setSex(rs.getString(4));                 student.setPhoto(rs.getString(5));                 studentList.add(student);              }       }finally {JdbcUtil.free(rs, ps, conn);}       return studentList;   }}

Servlet：

package servlet;import java.io.File;import java.io.IOException;import java.io.PrintWriter;import java.util.List;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 com.oreilly.servlet.MultipartRequest;import com.oreilly.servlet.multipart.DefaultFileRenamePolicy;import com.oreilly.servlet.multipart.FileRenamePolicy;import dao.StudentDao;import entity.Student;/** * Servlet implementation class StudentServlet */@WebServlet("/admin/studentServlet")public class StudentServlet extends HttpServlet {    private static final long serialVersionUID = 1L;    StudentDao studentDao = new StudentDao();    /**     * @see HttpServlet#HttpServlet()     */    public StudentServlet() {        super();        // TODO Auto-generated constructor stub    }    /**     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse     *      response)     */    protected void doGet(HttpServletRequest request,            HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        this.doPost(request, response);    }    /**     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse     *      response)     */    protected void doPost(HttpServletRequest request,            HttpServletResponse response) throws ServletException, IOException {        // TODO Auto-generated method stub        request.setCharacterEncoding("UTF-8");        String op = request.getParameter("op");        if ("add".equals(op)) {            this.add(request, response);        } else if ("update".equals(op)) {            this.update(request, response);        } else if ("delete".equals(op)) {            this.delete(request, response);        } else if ("query".equals(op)) {            this.query(request, response);        }    }    private void add(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // TODO Auto-generated method stub        String saveDirectory =this.getServletContext().getRealPath("/photo");          int maxPostSize =3  * 1024 * 1024 ;         String info="";        FileRenamePolicy policy =(FileRenamePolicy)new DefaultFileRenamePolicy();        MultipartRequest multi = new MultipartRequest(request, saveDirectory, maxPostSize,"utf-8",policy);        String photo=multi.getFilesystemName("photo");        if(photo==null){            photo="";        }        StudentDao studentDao = new StudentDao();        try {                           Student student = new Student();                student.setSno(multi.getParameter("sno"));                student.setSname(multi.getParameter("sname"));                student.setSex(multi.getParameter("sex"));                student.setPhoto(photo);                studentDao.add(student);                info="添加成功";                   } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();            info="添加失败";                   }        request.setAttribute("info",info);        request.getRequestDispatcher("/admin/student/add.jsp").forward(request, response);           }    private void update(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // TODO Auto-generated method stub        String saveDirectory =this.getServletContext().getRealPath("/photo");                 int maxPostSize =3  * 1024 * 1024 ;  //���ϴ���С���ƣ�3M        FileRenamePolicy policy =(FileRenamePolicy)new DefaultFileRenamePolicy();        MultipartRequest multi = new MultipartRequest(request, saveDirectory, maxPostSize,"utf-8",policy);        String photo=multi.getFilesystemName("photo");        String oldphoto=multi.getParameter("oldphoto");        if(photo==null){            photo=oldphoto;        }        else{            if(!"".equals(oldphoto))                new File(saveDirectory+"/"+oldphoto).delete();        }            StudentDao studentDao = new StudentDao();            try {                   Student student = new Student();                    student.setId(Integer.parseInt(multi.getParameter("id")));                   student.setSno(multi.getParameter("sno"));                   student.setSname(multi.getParameter("sname"));                   student.setSex(multi.getParameter("sex"));                   student.setPhoto(photo);                   studentDao.update(student);                   response.sendRedirect("/zdwxz/admin/studentServlet?op=query");            } catch (Exception e) {                // TODO Auto-generated catch block                e.printStackTrace();                response.setContentType("text/html;charset=UTF-8");                PrintWriter out = response.getWriter();                out.print("alert('更新失败')");            }    }    private void delete(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // TODO Auto-generated method stub               try {            studentDao.delete(Integer.parseInt(request.getParameter("id")));            String photo=request.getParameter("photo");            String appPath=this.getServletContext().getRealPath("/photo");            if(!"".equals(photo))              new File(appPath+"/"+photo).delete();            response.sendRedirect("/zdwxz/admin/studentServlet?op=query");        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }    private void query(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        // TODO Auto-generated method stub        try {            List studentList=studentDao.query();            request.setAttribute("studentList",studentList );           request.getRequestDispatcher("/admin/student/query.jsp").forward(request, response);        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();        }    }}