servlet+jdbc实现用户注册功能

发布时间：2023年12月29日

一、需求

在Servlet中可以使用JDBC技术访问数据库，常见功能如下：

查询DB数据，然后生成显示页面，例如：列表显示功能。
接收请求参数，然后对DB操作，例如：注册、登录、修改密码等功能。

二、代码演示

1、编写注册界面

创建空工程，在工程中创建javaEE模块
配置中设置tomcat的部署

编写register界面

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>简单注册界面</title>
</head>
<body>

<form action="register" method="post">
  用户名：<input type="text" name="userName"/><br>
  密码：<input type="text" name="password"><br>
  <input type="submit" value="注册">

</form>

</body>
</html>

2、编写Servlet 获取注册信息

编写servlet

RegisterServlet

 ```java
 package com.example.register_demo01;
 
 import javax.servlet.*;
 import javax.servlet.http.*;
 import java.io.IOException;
 
 public class RegisterServlet extends HttpServlet {
     @Override
     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         this.doPost(request, response);
     }
 
     @Override
     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
         //1、获取请求的用户名和密码
         String userName = request.getParameter("userName");
         System.out.println("获取到的用户名为：" + userName);
         String password = request.getParameter("password");
         System.out.println("获取到的密码为：" + password);
     }
 }
 ```

web.xml

<?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>RegisterServlet</servlet-name>
        <servlet-class>com.example.register_demo01.RegisterServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>RegisterServlet</servlet-name>
        <url-pattern>/register</url-pattern>
    </servlet-mapping>
</web-app>

部署测试：
- 运行tomcat
- 访问注册界面，发送注册请求，tomcat获取注册信息

3、创建原始User类

package com.example.register_demo01.pojo;

public class User {
    private int id;
    private String userName;
    private String password;
    
    public User(){}

    public User(String userName, String password) {
        this.userName = userName;
        this.password = password;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    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;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", userName='" + userName + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

4、创建数据库

在这里插入图片描述

5、创建DbUtil，使用jdbc控制数据库

代码：

package com.example.register_demo01.utils;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DbUtil {
    private static String jdbcName;
    private static String dbUrl;
    private static String dbUserName;
    private static String dbPassword;

    //静态初始化操作
    static {
        jdbcName = "com.mysql.jdbc.Driver";
        dbUrl = "jdbc:mysql://localhost:3306/db_web";
        dbUserName = "root";
        dbPassword = "root";
        try {
            Class.forName(jdbcName);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() throws SQLException {
        Connection connection = DriverManager.getConnection(dbUrl, dbUserName, dbPassword);
        return connection;
    }

    public static void closeConnection(Connection con) throws SQLException {
        if (null != con){
            con.close();
        }
    }

}

6、编写UserDao，将User对象存储到数据库

代码：

package com.example.register_demo01.dao;

import com.example.register_demo01.pojo.User;
import com.example.register_demo01.utils.DbUtil;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class UserDao {

    public int createUser(User user) {
        Connection connection = null;
        PreparedStatement preparedStatement = null;

        try {
            //1、获取连接
            Connection connection1 = DbUtil.getConnection();
            //2、准备sql
            String sql = "insert into t_user values(null, ?, ?)";
            //3、获取PreparedStatement
            preparedStatement = connection.prepareStatement(sql);
            //4、向问号位置设置数据
            preparedStatement.setString(1, user.getUserName());
            preparedStatement.setString(2, user.getPassword());
            //5、执行sql
            int row = preparedStatement.executeUpdate();
            return row;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            //6、关闭资源
            try {
                DbUtil.closeConnection(connection);
                if(preparedStatement != null){
                    preparedStatement.close();
                }
            } catch (SQLException throwables) {
                throwables.printStackTrace();
            }
        }
        return -1;//执行失败

    }
}

7、修改Servlet，添加保存进数据库的操作

代码：

package com.example.register_demo01;

import com.example.register_demo01.dao.UserDao;
import com.example.register_demo01.pojo.User;

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;
import java.io.PrintWriter;

public class RegisterServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1、获取请求的用户名和密码
        String userName = request.getParameter("userName");
        System.out.println("获取到的用户名为：" + userName);
        String password = request.getParameter("password");
        System.out.println("获取到的密码为：" + password);
        //2、封装user信息，将信息保存到数据库
        User user = new User(userName, password);
        UserDao userDao = new UserDao();
        int res = userDao.createUser(user);
        //3、将处理结果响应到浏览器
        response.setContentType("text/html;charset=utf-8");
        PrintWriter writer = response.getWriter();
        if (1 == res){
            System.out.println("注册成功");
            writer.write("<h1>注册成功！</h1>");
        }else {
            System.out.println("注册失败");
            writer.write("<h1>注册失败！</h1>");

        }
        writer.close();


    }
}

测试结果：

文章来源:https://blog.csdn.net/CAUC_lin/article/details/135295162
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