注册，登录

以下为具体代码：

public class JDBCUtils {private static String url;private static String user;private static String password;private static String driver;//读取文件，只需读取一次即可拿到这些值，使用静态代码块static {try {//创建Properties集合类Properties pro = new Properties();//获取src路径下文件→ClassLoader 类加载器ClassLoader classLoader = JDBCUtils.class.getClassLoader();URL res = classLoader.getResource("jdbc.properties");String path = res.getPath();System.out.println(path);//加载文件pro.load(new FileReader(path));//获得数据，赋值url = pro.getProperty("url");user = pro.getProperty("user");password = pro.getProperty("password");driver = pro.getProperty("driver");//注册驱动Class.forName(driver);}catch (IOException e){e.printStackTrace();}catch (ClassNotFoundException e1){e1.printStackTrace();}}//连接public static Connection getConnection() throws SQLException {return DriverManager.getConnection(url,user,password);}//释放资源public static void close(ResultSet rs, Statement stmt,Connection conn) throws SQLException {if (rs != null){rs.close();}if (stmt!=null){stmt.close();}if(conn!= null) {conn.close();}}public static void close(Statement stmt,Connection conn) throws SQLException {if (stmt!=null){stmt.close();}if(conn!= null) {conn.close();}}}public boolean register(String username, String password) throws SQLException {if (username == null || password == null){return false;}Connection conn = null;Statement stmt = null;ResultSet rs = null;try{conn = JDBCUtils.getConnection();//定义sqlString sql ="select * from user where name = '"+username+"' ";stmt = conn.createStatement();//执行查询rs = stmt.executeQuery(sql);if(rs.next()){System.out.println("改账号已存在!");return false;}String sql_2 = "INSERT into user (name,password) VALUES('"+username+"','"+password+"')";stmt = conn.createStatement();if (stmt.executeUpdate(sql_2)>=1)return true;return false;}catch (SQLException e) {e.printStackTrace();}finally {JDBCUtils.close(rs,stmt,conn);}return false;}public static void main(String[] args) throws ClassNotFoundException, SQLException {Scanner sc = new Scanner(System.in);System.out.println("请输入用户名:");String username = sc.nextLine();System.out.println("请输入密码:");String password = sc.nextLine();System.out.println("请再次输入密码:");String password_2 = sc.nextLine();if (password.equals(password_2)){boolean flag = new jdbc_test().register(username,password);if(flag){System.out.println("注册成功!");}else {System.out.println("注册失败");}}else {System.out.println("两次密码不同！");}}url = jdbc:mysql://localhost:3306/test01?useSSL = false
user = root
password = 123456
driver = com.mysql.jdbc.Driver

运行结果截图