Javaweb小练习---在JSP中使用Javabean访问数据库完成用户信息的简单添加
目录
Javaweb小练习---在JSP中使用Javabean访问数据库完成用户信息的简单添加
0.创建数据库
1.
在resources目录下创建db.properties文件
2.
/**
* 获取链接与释放资源的工具类--JdbcUtil类
*/
3.
/*** 实体类---建立该类实现记录信息对象化*/
4.在User类基础上，建立UserDao类，封装基本的数据库操作
5.创建数据提交页面----a.jsp
6.计算加工页面-----b.jsp
7.显示信息页面-----c.jsp
8.项目结构：
0.创建数据库
-- 创建数据库test
-- 创建数据库test
CREATE DATABASE IF NOT EXISTS test DEFAULT CHARSET utf8mb4 COLLATE utf8mb4_unicode_ci;
-- 切换到test数据库
USE test;
-- 创建数据表user
CREATE TABLE IF NOT EXISTS user (
userid VARCHAR(10) PRIMARY KEY,
username VARCHAR(20) NOT NULL,
sex VARCHAR(10) NOT NULL
) ENGINE=INNODB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
SELECT *
FROM user 
1.
在resources目录下创建db.properties文件
driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/test
username=root
password=1234562.
/**
* 获取链接与释放资源的工具类--JdbcUtil类
*/
package jdbc;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;
/**
* 获取链接与释放资源的工具类--JdbcUtil类
*/
public class JdbcUtil{
private static String driver;
private static String url;
private static String username;
private static String password;
private static Properties properties = new Properties();
public JdbcUtil() {
}
static {
try {
//设计该工具类的静态初始化器中的代码，该代码在装入类时执行，且执行一次
//加载属性文件，并在JdbcUtil雷中可读取其中的属性值
properties.load(JdbcUtil.class.getClassLoader().getResourceAsStream("db.properties"));
driver = properties.getProperty("driver");
url = properties.getProperty("url");
username = properties.getProperty("username");
password = properties.getProperty("password");
Class.forName(driver);
}catch (Exception e){
//throw new ExceptionInInitializerError(e);
System.out.println(e);
}
}
//设计获得连接对象的方法getConnection（）
public static Connection getConnection() throws Exception{
Connection connection=null;
try{
//1-读取db.properties文件
Properties properties = new Properties();
InputStream in = JdbcUtil.class.getResourceAsStream("/db.properties");
properties.load(in);
//2-读取属性
String driver=properties.getProperty("driver");
String url=properties.getProperty("url");
String username=properties.getProperty("username");
String password=properties.getProperty("password");
//3-注册驱动
Class.forName(driver);
//4-获取连接
connection= DriverManager.getConnection(url,username,password);
//5-日志打印连接信息
System.out.println("连接信息: " + url + " " + username + " " + password);
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException("数据库连接失败，请检查连接参数是否正确！");
}
return connection;
}
//设计释放结果集、语句和连接方法free()
public static void free(ResultSet resultSet, Statement statement,Connection connection)throws Exception{
if (resultSet!=null){resultSet.close();}
if (statement!=null){statement.close();}
if (connection!=null){connection.close();}
}
}
3.
/**
* 实体类---建立该类实现记录信息对象化
*/
package vo;
/**
* 实体类---建立该类实现记录信息对象化
*/
public class User {
private String userid;
private String username;
private String sex;
public User() {
}
public User(String userid, String username, String sex) {
this.userid = userid;
this.username = username;
this.sex = sex;
}
public String getUserid() {
return userid;
}
public void setUserid(String userid) {
this.userid = userid;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
}
4.在User类基础上，建立UserDao类，封装基本的数据库操作
package dao;
import jdbc.JdbcUtil;
import vo.User;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;
/**
* 在User类基础上，建立UserDao类，封装基本的数据库操作
*/
public class UserDao {
//1-向数据库中添加用户的方法add（User user），将对象user插入数据表中
public void add(User user)throws Exception{
Connection connection= JdbcUtil.getConnection();
String sql="insert into user(userid,username,sex) values(?,?,?)";
PreparedStatement preparedStatement=connection.prepareStatement(sql, ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
preparedStatement.setString(1,user.getUserid());
preparedStatement.setString(2,user.getUsername());
preparedStatement.setString(3,user.getSex());
preparedStatement.executeUpdate();
JdbcUtil.free(null,preparedStatement,connection);
}
//2-修改数据库用户记录方法update(User user),将对象user进行修改
public void update(User user)throws Exception{
Connection connection= JdbcUtil.getConnection();
String sql="update user set username=?,sex=? where userid=?";
PreparedStatement preparedStatement=connection.prepareStatement(sql);
preparedStatement.setString(1,user.getUsername());
preparedStatement.setString(2,user.getSex());
preparedStatement.setString(3,user.getUserid());
preparedStatement.executeUpdate();
JdbcUtil.free(null,preparedStatement,connection);
}
//3-删除数据库用户记录方法delete(String userId),根据userId值进行删除记录
public void delete(String userId)throws Exception{
Connection connection=JdbcUtil.getConnection();
String sql="delete from user where userid=?";
PreparedStatement preparedStatement=connection.prepareStatement(sql);
preparedStatement.setString(1,userId);
preparedStatement.executeUpdate();
JdbcUtil.free(null,preparedStatement,connection);
}
//4-根据id查询用户方法findUserById（）
public User findUserById(String userId)throws Exception{
Connection connection=JdbcUtil.getConnection();
User user=null;
String sql="select * from user where userid=?";
PreparedStatement preparedStatement=connection.prepareStatement(sql);
preparedStatement.setString(1,userId);
ResultSet resultSet=preparedStatement.executeQuery();
if (resultSet.next()){
user=new User();
user.setUserid(resultSet.getString("userid"));
user.setUsername(resultSet.getString("username"));
user.setSex(resultSet.getString("sex"));
}
JdbcUtil.free(resultSet,preparedStatement,connection);
return user;
}
//5-查询全部用户的方法QueryAll()
public List<User>QueryAll()throws Exception{
Connection connection=JdbcUtil.getConnection();
List<User> userList=new ArrayList<>();
String sql="select * from user";
PreparedStatement preparedStatement=connection.prepareStatement(sql);
ResultSet resultSet=preparedStatement.executeQuery();
while (resultSet.next()){
User user=new User();
user.setUserid(resultSet.getString("userid"));
user.setUsername(resultSet.getString("username"));
user.setSex(resultSet.getString("sex"));
userList.add(user);
}
JdbcUtil.free(resultSet,preparedStatement,connection);
return userList;
}
}
5.创建数据提交页面----a.jsp
<%--
Created by IntelliJ IDEA.
User: CaptainDong
Date: 2023/4/9
Time: 11:59
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@page pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<title>数据提交页面</title>
</head>
<body>
<form action="b.jsp" method="post">
<table>
<tr>
<td>
编号：
</td>
<td>
<input type="text" name="userid" required>
</td>
</tr>
<tr>
<td>
姓名：
</td>
<td>
<input type="text" name="username" required>
</td>
</tr>
<tr>
<td>
性别：
</td>
<td>
<input type="text" name="sex" required>
</td>
</tr>
<tr>
<td colspan="2">
<button type="submit">提交</button>
<button type="reset">重置</button>
</td>
</tr>
</table>
</form>
</body>
</html>
6.计算加工页面-----b.jsp
<%@ page import="vo.User" %>
<%@ page import="dao.UserDao" %>
<%@ page import="java.util.List" %>
<%@ page import="java.sql.SQLException" %><%--
Created by IntelliJ IDEA.
User: CaptainDong
Date: 2023/4/9
Time: 11:59
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>计算加工页面</title>
</head>
<body>
<%
request.setCharacterEncoding("UTF-8");
String user_id=request.getParameter("userid");
String user_name=request.getParameter("username");
String user_sex=request.getParameter("sex");
User user=new User(user_id,user_name,user_sex);
UserDao userDao=new UserDao();
//userDao.add(user);
// 实现插入
try {
userDao.add(user);
} catch (SQLException e) {
e.printStackTrace();
}
List<User>users=userDao.QueryAll();
request.setAttribute("users_list",users);
%>
//转到c.jsp网页
<jsp:forward page="c.jsp"></jsp:forward>
</body>
</html>
7.显示信息页面-----c.jsp
<%@ page import="java.util.List" %>
<%@ page import="vo.User" %><%--
Created by IntelliJ IDEA.
User: CaptainDong
Date: 2023/4/9
Time: 11:59
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>显示信息页面</title>
</head>
<body>
<%
List<User>users=(List<User>) (request.getAttribute("users_list"));
for (int i=0;i<users.size();i++){
User user=users.get(i);
String abc="编号："+user.getUserid()+"_姓名："+user.getUsername()+"_性别："+user.getSex();
out.println(abc);
}
%>
</body>
</html>
8.项目结构：
