什么是MVC模式
MVC模式中M代表模型、V代表视图、C代表控制器。
Model（模型）表示应用程序核心（比如数据库记录列表）。
View（视图）显示数据（数据库记录）。
Controller（控制器）处理输入（写入数据库记录）。
数据库设计
表名：student、使用的为mysql数据库
M层
package cn.jdbc.domain;public class student {//学号private String sno;//姓名private String sname;//年龄private int sage;public String getSno() { return sno;}public void setSno(String sno) { this.sno = sno;}public String getSname() { return sname;}public void setSname(String sname) { this.sname = sname;}public int getSage() { return sage;}public void setSage(int sage) { this.sage = sage;}}V层
jsp页面
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>学生数据</title></head><body> <table border="1" border="1" cellpadding="0" cellspacing="0" width="100%"> <thead> <tr> <th>学号</th> <th>姓名</th> <th>年龄</th> </tr> </thead> <tbody> <c:forEach items="${list}" var="i"> <tr > <td>${i.sno}</td> <td>${i.sname}</td> <td>${i.sage}</td> </tr> </c:forEach> </tbody> </table> <form action="/sy3/display" method="post"> <label>查询的学号</label> <input type="text" name="search_no" value=""> <input type="submit" value="查询"> <a href="http://localhost:9999/sy3/display">返回</a><br> </form> <h5>添加数据</h5> <form action="/sy3/display" method="post"> <label>学号</label> <input type="text" name="add_sno" value=""> <label>姓名</label> <input type="text" name="add_sname" value=""> <label>年龄</label> <input type="text" name="add_sage" value=""> <input type="submit" value="添加"> </form> <h5>修改数据</h5> <form action="/sy3/display" method="post"> <label>学号</label> <input type="text" name="cg_sno" value=""> <label>姓名</label> <input type="text" name="cg_sname" value=""> <label>年龄</label> <input type="text" name="cg_sage" value=""> <input type="submit" value="修改"> </form> <h5>删除数据</h5> <form action="/sy3/display" method="post"> <label>删除数据学生的学号</label> <input type="text" name="del_sno" value=""> <input type="submit" value="删除"> </form></body></html>servlet负责jsp页面与数据库的数据交互
package cn.jdbc.servlet;import java.io.IOException;import java.util.ArrayList;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 cn.jdbc.dao.StudentDao;import cn.jdbc.domain.student;import cn.jdbc.test.search_id;/** * Servlet implementation class display */@WebServlet("/display")public class display extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public display() { 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 //获取数据库操作的对象 StudentDao dao = new StudentDao(); //获取数组对象 List<student> list = new ArrayList<student>(); //获取查询的学号 String search_sno = request.getParameter("search_no"); //获取添加的数据 String add_sno = request.getParameter("add_sno"); String add_sname = request.getParameter("add_sname"); String add_sage = request.getParameter("add_sage"); //获取修改的数据 String cg_sno = request.getParameter("cg_sno"); String cg_sname = request.getParameter("cg_sname"); String cg_sage = request.getParameter("cg_sage"); //获取删除的学号 String del_sno = request.getParameter("del_sno"); //查询数据 if(search_sno!=null){ student student= dao.find(search_sno); list.add(student); search_sno=""; }else{//显示所有的数据 list=dao.findAll(); } //添加数据 if(add_sage!=null){ student student = new student(); student.setSno(add_sno); student.setSname(add_sname); student.setSage(Integer.parseInt(add_sage)); dao.insert(student); list=dao.findAll(); add_sno=""; add_sname=""; add_sage=""; } //修改数据 if(cg_sage!=null){ student student = new student(); student.setSno(cg_sno); student.setSname(cg_sname); student.setSage(Integer.parseInt(cg_sage)); dao.update(student); list=dao.findAll(); cg_sno=""; cg_sname=""; cg_sage=""; } //删除数据 if(del_sno!=null){ dao.delete(del_sno); list=dao.findAll(); del_sno=""; } //传递数组到jsp页面 request.setAttribute("list", list); request.getRequestDispatcher("index.jsp").forward(request, response); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doGet(request, response); }}C层
工具类（负责连接数据库）
package cn.jdbc.utils;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class utils {// 加载驱动，并建立数据库连接 public static Connection getConnection() throws SQLException, ClassNotFoundException {// 加载驱动 Class.forName("com.mysql.jdbc.Driver");// 获取数据库连接 String url = "jdbc:mysql://localhost:3306/kinjaze";// 用户名 String username = "root";// 密码 String password = "********"; Connection conn = DriverManager.getConnection(url, username, password); return conn; } // 关闭数据库连接，释放资源 public static void release(ResultSet rs, Statement stmt, Connection conn) { if (rs != null) { try { rs.close(); } catch (SQLException e) { e.printStackTrace(); } rs = null; } if (stmt != null) { try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } stmt = null; } if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } conn = null; } }}实现数据库的增删改查的操作类
package cn.jdbc.dao;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.Statement;import java.text.SimpleDateFormat;import java.util.ArrayList;import java.util.List;import cn.jdbc.domain.student;import cn.jdbc.utils.utils;/* * 完成对数据库的增删改查操作 */public class StudentDao { //为学生表添加数据 public boolean insert(student student) { Connection conn = null; PreparedStatement stmt = null; ResultSet rs = null; try { // 获得数据的连接 conn = utils.getConnection(); // SQL语句 String sql="insert into student values(?,?,?)"; //得到预编译对象 stmt=conn.prepareStatement(sql); stmt.setString(1, student.getSno()); stmt.setString(2, student.getSname()); stmt.setInt(3, student.getSage()); int num = stmt.executeUpdate(); if (num > 0) { return true; } return false; } catch (Exception e) { e.printStackTrace(); } finally { utils.release(rs, stmt, conn); } return false; } //查询所有数据 public List < student > findAll() { Connection conn = null; PreparedStatement stmt = null; ResultSet rs = null; List < student > list = new ArrayList < student > (); try { // 获得数据的连接 conn = utils.getConnection(); // SQL语句 String sql="select * from student"; //得到预编译对象 stmt=conn.prepareStatement(sql); rs = stmt.executeQuery(); // 处理结果集,遍历rs结果集 while (rs.next()) { student student = new student(); student.setSno(rs.getString("sno")); student.setSname(rs.getString("sname")); student.setSage(rs.getInt("sage")); list.add(student); } return list; } catch (Exception e) { e.printStackTrace(); } finally { utils.release(rs, stmt, conn); } return null; } // 根据id查找指定的student public student find(String id) { Connection conn = null; PreparedStatement stmt = null; ResultSet rs = null; student student = new student(); try { // 获得数据的连接 conn = utils.getConnection(); //SQL语句 String sql = "select * from student where sno=?"; //得到预编译对象 stmt=conn.prepareStatement(sql); stmt.setString(1, id); rs = stmt.executeQuery(); // 处理结果集 while (rs.next()) { student.setSno(rs.getString("sno")); student.setSname(rs.getString("sname")); student.setSage(rs.getInt("sage")); return student; } return null; } catch (Exception e) { e.printStackTrace(); } finally { utils.release(rs, stmt, conn); } return null; } //删除学生数据 public boolean delete(String id){ Connection conn = null; PreparedStatement stmt = null; ResultSet rs = null; try { // 获得数据的连接 conn = utils.getConnection(); //sql语句 String sql = "delete from student where sno=?"; //获取预处理对象 stmt= conn.prepareStatement(sql); stmt.setString(1, id); int num = stmt.executeUpdate(); if (num > 0) { return true; } return false; } catch (Exception e) { e.printStackTrace(); } finally { utils.release(rs, stmt, conn); } return false; } // 修改用户 public boolean update(student student) { Connection con = null; PreparedStatement stmt = null; ResultSet rs = null; try { //获得数据的连接 con = utils.getConnection(); //sql语句 String sql="update student set sname=?,sage=? where sno =?"; //得到预编译对象 stmt=con.prepareStatement(sql); stmt.setString(1, student.getSname()); stmt.setInt(2, student.getSage()); stmt.setString(3, student.getSno()); int num = stmt.executeUpdate(); if (num > 0) { return true; } return false; } catch (Exception e) { e.printStackTrace(); } finally { utils.release(rs, stmt, con); } return false; }}有其他问题可以私聊作者交流