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
image.png
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" %>
学生数据
学号
姓名
年龄
${i.sno}
${i.sname}
${i.sage}
添加数据
修改数据
删除数据
image.png
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 list = new ArrayList();
//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;
}
}
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