JavaWeb连接数据库实现页面登录、注册和增删改查

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2024-04-23 帮助1人

<%--
Created by IntelliJ IDEA.
User: Lenovo
Date: 2023/2/15
Time: 11:13
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登录页面</title>
</head>
<body>
<h2>登录</h2>
<form action="login" method="post">
账户:<input type="text" name="username" value="" /><br/>
密码:<input type="password" name="password" value="" /><br/>
<input type="submit" value="登录" />
</form>
</body>
</html>

登陆成功页面

<%--
Created by IntelliJ IDEA.
User: Lenovo
Date: 2023/2/17
Time: 20:01
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>主页面</title>
</head>
<body>
<h2>登陆成功!</h2>
</body>
</html>

登陆失败页面

<%--
Created by IntelliJ IDEA.
User: Lenovo
Date: 2023/2/17
Time: 20:00
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>错误</title>
</head>
<body>
<h2>登录失败!</h2>
<a href="login.jsp">返回登录</a>
</body>
</html>

在User类中写入实体、属性、方法

package bean;
public class User {
private Integer uid;
private String username;
private String password;
private String phone;
private String address;
public User() {
}
public Integer getUid() {
return uid;
}
public void setUid(Integer uid) {
this.uid = uid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "User{"
"uid=" uid
", username='" username '\''
", password='" password '\''
", phone='" phone '\''
", address='" address '\''
'}';
}
}

UserDaoImpl中写登录和注册的代码

package dao;
import bean.User;
import util.JDBCUtil;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class UserDaoImpl{
private Connection con=null;//数据库连接对象
private PreparedStatement ps=null;//预处理对象
private ResultSet rs=null;//结果集对象
private int row=0;//增删改受影响的行数
User login=null;
public User login(String username, String password) {
try {
con= JDBCUtil.getCon();
//3.定义sql语句
String sql = "select * from t_user where username=? and password=?";
//4.获取预处理对象
ps = con.prepareStatement(sql);
//5.传参
ps.setObject(1, username);
ps.setObject(2, password);
//6.执行sql语句
rs = ps.executeQuery();
//7.结果集处理
if (rs.next()) {
login=new User();
//从结果集获取数据，封装到实体类对象中
int uid=rs.getInt("uid");
login.setUid(uid);
login.setUsername(rs.getString("username"));
login.setPassword(rs.getString("password"));
login.setPhone(rs.getString("phone"));
login.setAddress(rs.getString("address"));
}
}catch (Exception e){
e.printStackTrace();
}finally {
JDBCUtil.close(rs,ps,con);
}
return login;
}
public int register(User user) {
try {
//1.获取数据库连接
con= JDBCUtil.getCon();
//2.定义sql语句
String sql="insert into t_user(username,password,phone,address) values(?,?,?,?)";
//3.获取预处理对象
ps=con.prepareStatement(sql);
//4.传参
ps.setObject(1,user.getUsername());
ps.setObject(2,user.getPassword());
ps.setObject(3,user.getPhone());
ps.setObject(4,user.getAddress());
//5.执行sql
row=ps.executeUpdate();
}catch (Exception e){
e.printStackTrace();
}finally {
JDBCUtil.close(ps,con);
}
return row;
}
}

JDBCUtil关闭数据库的媒介

package util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class JDBCUtil {
private static String driver="com.mysql.cj.jdbc.Driver";
private static String url="jdbc:mysql://localhost:3306/mydb?useSSL=false&serverTimezone=UTC";
private static String user="root";
private static String password="root";
private static Connection con=null;
private static PreparedStatement ps=null;
private static ResultSet rs=null;
public static Connection getCon(){
try {
//1.加载数据库驱动
Class.forName(driver);
//2.获取数据库连接对象
con= DriverManager.getConnection(url,user,password);
}catch (Exception e){
e.printStackTrace();
}
return con;
}
public static void close(ResultSet rs,PreparedStatement ps,Connection con){
try {
if (rs!=null){
rs.close();
}
if (ps!=null){
ps.close();
}
if (con!=null){
con.close();
}
}catch (Exception e){
e.printStackTrace();
}
}
public static void close(PreparedStatement ps,Connection con){
try {
if (ps!=null){
ps.close();
}
if (con!=null){
con.close();
}
}catch (Exception e){
e.printStackTrace();
}
}
}

在web.xml中获取请求

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<servlet>
<servlet-name>login</servlet-name>
<servlet-class>Zuoye.Login</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
</web-app>

在Login类中连接数据库

package Zuoye;
import bean.User;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class Login extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//设置请求和响应的编码
req.setCharacterEncoding("utf-8");//设置请求的编码
resp.setCharacterEncoding("utf-8");//设置响应的编码
resp.setContentType("text/html;charset=utf-8");//设置响应的文本格式和编码
//获取请求参数
String username = req.getParameter("username");
String password = req.getParameter("password");
//业务处理--JDBC操作
Connection con=null;//数据库连接对象
PreparedStatement pstm=null;//预处理对象
ResultSet rs=null;//结果集
User login=null;
try {
//加载驱动包
Class.forName("com.mysql.cj.jdbc.Driver");
//获取数据库连接对象
con= DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/mydb?useSSL=false&serverTimezone=UTC","root","root");
//定义sql语句
String sql="select * from t_user where username=? and password=?";
//获取预处理对象
pstm = con.prepareStatement(sql);
//传参
pstm.setObject(1,username);
pstm.setObject(2,password);
//执行SQL
rs=pstm.executeQuery();
//结果集处理
if (rs.next()){
login=new User();
//结果集中获取数据，封装到实体类对象中
int uid = rs.getInt("uid");
login.setUid(uid);
login.setUsername(rs.getString("username"));
login.setPassword(rs.getString("password"));
login.setPhone(rs.getString("phone"));
login.setAddress(rs.getString("address"));
}
}catch (Exception e){
e.printStackTrace();
}finally {
//关闭资源
try {
if (rs!=null){
rs.close();
}
if (pstm!=null){
pstm.close();
}
if (con!=null){
con.close();
}
}catch (Exception e){
e.printStackTrace();
}
}
//判断登录的用户信息是否为空
if (login!=null){
//登陆成功跳转到主页
resp.sendRedirect("zhuye.jsp");
}else{
//登陆失败跳转到错误页面
resp.sendRedirect("error.jsp");
}
}
}

注册

页面

<%--
Created by IntelliJ IDEA.
User: Lenovo
Date: 2023/2/18
Time: 16:55
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>注册页面</title>
</head>
<body>
<h1>进行注册</h1>
<form action="register" method="post">
账号:<input type="text" name="username" value="" /><br/>
密码:<input type="password" name="password" value="" /><br/>
电话:<input type="text" name="phone" value="" /><br/>
地址:<input type="text" name="address" value="" /><br/>
<input type="submit" value="注册">
<a href="login.jsp">已有账号,去登录</a>
</form>
</body>
</html>

运行的代码

package servlet;
import bean.User;
import dao.UserDaoImpl;
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;
@WebServlet("/register")
public class Register extends HttpServlet {
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//设置请求和响应的编码
req.setCharacterEncoding("utf-8"); //设置请求的编码
resp.setCharacterEncoding("utf-8"); //设置响应的编码
//获取请求参数
String username = req.getParameter("username");
String password = req.getParameter("password");
String phone = req.getParameter("phone");
String address = req.getParameter("address");
//封装到User对象中
User user = new User();
user.setUsername(username);
user.setPassword(password);
user.setPhone(phone);
user.setAddress(address);
System.out.println(user);
//JDBC操作
UserDaoImpl userDao = new UserDaoImpl();
int row = userDao.register(user);
//做出响应
if (row > 0) {
//注册成功
resp.sendRedirect("login.jsp");
} else {
//注册失败
resp.sendRedirect("register.jsp");
}
}
}

将数据库显示到页面

后台获取数据

HttpSession session=request.getSession();
session.setAttribute("goodsList",goodsList);

导入jstl核心类库

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

通过el表达式展示

<h2>欢迎来到${user.address}的${user.username}的页面!</h2>
<table>
<tr>
<th>商品编号</th>
<th>商品名称</th>
<th>商品价格</th>
<th>商品说明</th>
</tr>
<c:forEach items="${goodsList}" var="goods">
<tr>
<td>${goods.gid}</td>
<td>${goods.gname}</td>
<td>${goods.price}</td>
<td>${goods.mark}</td>
</tr>
</c:forEach>
</table>

新增数据

添加页面

<%--
Created by IntelliJ IDEA.
User: Lenovo
Date: 2023/2/15
Time: 11:13
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>商品信息添加</title>
</head>
<body>
<h2>商品信息录入</h2>
<form action="addGoods" method="post">
商品名称: <input type="text" name="gname" value="" /><br/>
商品价格: <input type="number" step="0.01" name="price" value="" /><br/>
商品说明: <input type="text" name="mark" value="" />   <br/>
<input type="submit" value="提交">
</form>
</body>
</html>

在GoodsDao中写入add方法

public int add(Goods goods) {
try {
//1.获取数据库连接
con= JDBCUtil.getCon();
//2.定义sql语句
String sql="insert into t_goods(gname,price,mark) values(?,?,?)";
//3.获取预处理对象
ps=con.prepareStatement(sql);
//4.传参
ps.setObject(1,goods.getGname());
ps.setObject(2,goods.getPrice());
ps.setObject(3,goods.getMark());
//5.执行sql
row=ps.executeUpdate();
}catch (Exception e){
e.printStackTrace();
}finally {
JDBCUtil.close(rs,ps,con);
}
return row;
}

添加的运行代码

package servlet;
import bean.Goods;
import dao.GoodsDao;
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;
@WebServlet("/addGoods")
public class AddGoods extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
super.doGet(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
resp.setCharacterEncoding("utf-8");
Goods goods=new Goods();
goods.setGname(req .getParameter("gname"));
goods.setPrice(Double.parseDouble(req.getParameter("price"))); //获欧字符中数字转换double数据
goods.setMark(req.getParameter("mark"));
GoodsDao goodsDao=new GoodsDao();
int row = goodsDao.add(goods);
// System.out.println(row);
if(row>0) {
req.getRequestDispatcher("SelectAllGodds").forward(req, resp);
}else{
// req.setAttribute("error_msg","添加商品信息失败!");
req.getRequestDispatcher("error.jsp").forward(req,resp);
}
}
}

删除数据

在主页面添加删除标签

学新通

在GoodsDao中写入deleteById方法

public int deleteById(int gid) {
try {
//1.获取数据库连接
con= JDBCUtil.getCon();
//2.定义sql语句
String sql="delete from t_goods where gid=?";
//3.获取预处理对象
ps=con.prepareStatement(sql);
//4.传参
ps.setObject(1,gid);
//5.执行sql
row=ps.executeUpdate();
}catch (Exception e){
e.printStackTrace();
}finally {
JDBCUtil.close(rs,ps,con);
}
return row;
}
}

删除的运行代码

package servlet;
import dao.GoodsDao;
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;
@WebServlet("/del")
public class DelGoods extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
int gid=Integer.parseInt(req.getParameter("gid"));
//根id执行数据库的删除
GoodsDao goodsDao=new GoodsDao() ;
int row = goodsDao.deleteById(gid);
if(row>0) {
//请求转发,查询所有商品信息(刷新)
req.getRequestDispatcher("SelectAllGodds").forward(req,resp);
} else{
req.setAttribute("error_msg","删除出现了问题!");
req.getRequestDispatcher("error.jsp").forward(req,resp);
}
}
}

修改数据

在主页面添加修改标签属性

学新通

修改页面

<%--
Created by IntelliJ IDEA.
User: Lenovo
Date: 2023/2/15
Time: 11:13
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>商品信息修改</title>
</head>
<body>
<h2>商品信息修改</h2>
<form action="UpdateGoods" method="post">
商品编号: <input type="text" name="gid" value="${goods.gid}" readonly="readonly" placeholder="商品编号"/><br/>
商品名称: <input type="text" name="gname" value="${goods.gname}" placeholder="商品名称" /><br/>
商品价格: <input type="number" step="0.01" name="price" value="${goods.price}" placeholder="商品价格"/><br/>
商品说明: <input type="text" name="mark" value="${goods.mark}" placeholder="商品说明"/>   <br/>
<input type="submit" value="修改">
</form>
</body>
</html>

获取数据库操作

public Goods selectById(int gid) {
Goods goods=new Goods();
List<Goods> goodslist=new ArrayList<>();
try {
con = JDBCUtil.getCon();
String sql = "select * from t_goods where gid=?";
ps = con.prepareStatement(sql);
ps.setObject(1,gid);
rs = ps.executeQuery();
while (rs.next()) {
//把当前数据行中的数据取出来，存储到Goods对象中
goods.setGid(rs.getInt("gid"));
goods.setGname(rs.getString("gname"));
goods.setPrice(rs.getDouble("price"));
goods.setMark(rs.getString("mark"));
//把Goods对象存储到集合中
goodslist.add(goods);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try{
if(rs!=null) {
rs.close();
}
if(ps!=null) {
ps.close();
}
if(con!=null){
con.close();
}
} catch (Exception e){
e.printStackTrace();
}
}
return goods;
}

存入request域中

package servlet;
import bean.Goods;
import dao.GoodsDao;
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;
@WebServlet("/FindByid")
public class FindByid extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
int gid=Integer.parseInt(req.getParameter("gid"));
//根据gid查询商品信息
GoodsDao goodsDao=new GoodsDao();
Goods goods=goodsDao.selectById(gid);
System.out.println(goods);
if(goods!=null){
//查询商品信息成功，在入request城中，然后请求转发到页面展示数据
req.setAttribute("goods",goods);
req.getRequestDispatcher("showGoods.jsp").forward(req,resp);
}else {
req.setAttribute("error_msg","修改出了异常!");
req.getRequestDispatcher("error.jsp").forward(req,resp);
}
}
}

修改数据的数据库操作

public int upda(Goods goods){
try {
con= JDBCUtil.getCon();
//编写sql语句
String sql="update t_goods set gname=?,price=?,mark=? where gid=?";
//获取预处理对象
ps = con.prepareStatement(sql);
//传参
ps.setObject(1,goods.getGname());
ps.setObject(2,goods.getPrice());
ps.setObject(3,goods.getMark());
ps.setObject(4,goods.getGid());
//执行sql语句
row= ps.executeUpdate();
}catch (Exception e){
e.printStackTrace();
}finally {
JDBCUtil.close(ps,con);
}
return row;
}

点击修改后跳转到后台请求

package servlet;
import bean.Goods;
import dao.GoodsDao;
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;
@WebServlet("/UpdateGoods")
public class UpdateGoods extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
resp.setCharacterEncoding("utf-8");
//获取表单提交的数据，封装到qods对象中
Goods goods=new Goods();
goods.setGid(Integer.parseInt(req.getParameter("gid")));
goods.setGname(req.getParameter("gname"));
goods.setPrice(Double.parseDouble(req.getParameter( "price")));
goods.setMark(req.getParameter("mark"));
System.out.println(goods);
//执行数据库JDBC的修改操作
GoodsDao goodsDao=new GoodsDao();
int row=goodsDao.upda(goods);
if(row>0){
req.getRequestDispatcher("SelectAllGodds").forward(req,resp);
}else {
req.setAttribute("error_msg","修改出了异常");
req.getRequestDispatcher("error.jsp").forward(req,resp);
}
}
}

这篇好文章是转载于：学新通技术网

JavaWeb连接数据库实现页面登录、注册和增删改查

登录

在Navicat创建数据库

登录页面

登陆成功页面

登陆失败页面

在User类中写入实体、属性、方法

UserDaoImpl中写登录和注册的代码

JDBCUtil关闭数据库的媒介

在web.xml中获取请求

在Login类中连接数据库

注册

页面

运行的代码

将数据库显示到页面

后台获取数据

导入jstl核心类库

通过el表达式展示

新增数据

添加页面

在GoodsDao中写入add方法

添加的运行代码

删除数据

在主页面添加删除标签

在GoodsDao中写入deleteById方法

删除的运行代码

修改数据

在主页面添加修改标签属性

修改页面

获取数据库操作

存入request域中

修改数据的数据库操作

点击修改后跳转到后台请求

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