第六次作业

科技2024-03-16 98

在这里插入代码片<head> <title>Title</title> </head> <body> <% Class.forName("com.mysql.jdbc.Driver"); String url = "jdbc:mysql://localhost:3306/book"; Connection connection = DriverManager.getConnection(url,"root","root"); /* Statement stmt = connection.createStatement(); String sql ="select * from user"; ResultSet rs =stmt.executeQuery(sql); while (rs.next()){ out.print(rs.getString("username")+"-"+rs.getString(3)+"<br>"); } */ String sql = "select * from user where username = ? and password = ?"; PreparedStatement ps = connection.prepareStatement(sql); ps.setString(1,request.getParameter("username")); ps.setString(2,request.getParameter("password")); // String sql = "insert into user(username,password,gender) values (?,?,?)"; ResultSet rs = ps.executeQuery(); while (rs.next()){ out.print(rs.getString("username")+"-"+rs.getString(3)+"<br>"); } %> </body> </html> 在这里插入代码片<%@ page import="java.sql.DriverManager" %> <%@ page import="java.sql.Connection" %> <%@ page import="java.sql.Statement" %> <%@ page import="com.media.bean.UserBean" %><%-- Created by IntelliJ IDEA. User: 和 Date: 2020/10/7 Time: 8:38 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <% //user对象实例化 UserBean user = new UserBean(); //给对象赋值 user.setUsername(request.getParameter("username")); user.setPassword(request.getParameter("password")); //数据库操作 //1 加载驱动程序 Class.forName("com.mysql.jdbc.Driver"); //如果执行到此位置报错标识驱动的jar包没有加载成功 //2 建立数据库连接 10.3.22.1 String url = "jdbc:mysql://127.0.0.1:3306/book?user=root&password=root";//book 为数据库名 Connection connection = DriverManager.getConnection(url);//获得连接对象 //alt + 回车自动导入类如果报此行有问题说明数据库的连接地址或用户名和密码有问题 //3 创建Statement对象执行sql语句 alt+enter 自动引入缺失的类 Statement stmt = connection.createStatement(); // sql 插入语句值是字符串必须使用单引号 String sql = "insert into user (username,password,gender,age) values('"+user.getUsername()+"','"+user.getPassword()+"',1,23)"; //String sql = "update user set status = 3 where id = 11"; //String sql = "delete from user where id = 11"; 执行sql语句时id 保证数据库中存在该数据 //使用Statement 对象执行sql语句增删改的数据库操作使用executeUpdate int count = stmt.executeUpdate(sql); //如果报此行有错误数码上一行的sql语句是有问题的请检查数据库 if(count == 0 ){ out.print("注册失败"); //如果能执行到此位置表示数据库操作是成功数据库的数据是没有发生变化否则的肯定有异常 }else{ out.print("注册成功"); } %> 在这里插入代码片<%-- Created by IntelliJ IDEA. User: 和 Date: 2020/10/7 Time: 8:14 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>$Title$</title> </head> <body> <form method="post" action="home.jsp"> 用户名:<input type="text" name="username"><br> 密码: <input type="text" name="password"><br> 性别: <input type="text" name="gender"><br> 年龄: <input type="text" name="age"><br> <button type="submit">注册</button> </form> </body> </html>

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