idea java代码想通过JDBCUtils实现一个连接数据库模拟登陆的功能

问题遇到的现象和发生背景

idea java代码想通过JDBCUtils实现一个连接数据库模拟登陆的功能结果输入正确的username和password也返回账号或密码错误

用代码块功能插入代码，请勿粘贴截图

package cn.itcast.jdbc;

import cn.itcast.domain.User;
import cn.itcast.utils.JDBCUtils;
import cn.itcast.utils.JDBCUtils_repeat;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Scanner;

public class jdbcDemo08_login {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入姓名：");
        String username = sc.next();
        System.out.println("请输入密码：");
        String password = sc.next();

        boolean flag = new jdbcDemo08_login().login(username, password);
        if (flag == true ){
            System.out.println("登陆成功！");
        }else {
            System.out.println("用户名或密码错误！");
        }
    }

    public boolean login(String username,String password){

        if (username == null || password ==null){
            return false;
        }

        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        //连接数据库
        try {
            conn = JDBCUtils_repeat.getConnection();
            /*String sql = "select * from user where username = ' "+username+"' and password = '"+password+"'";*/
            String sql = "select * from user where username = ? and password = ? ";
            ps = conn.prepareStatement(sql);
            ps.setString(1,"username");
            ps.setString(2,"password");
            rs = ps.executeQuery();
            return rs.next();  //如果有下一行，返回true
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            JDBCUtils_repeat.close(rs,ps,conn);
        }
        return false;
    }
}