JDBC login case implementation

Code:

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public class Login {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("请输入用户名：");
        String username = in.nextLine();
        System.out.println("请输入密码：");
        String password = in.nextLine();

        boolean flag = new Login().login(username, password);

        if (flag) {
            //登陆成功
            System.out.println("登陆成功！");
        } else {
            //登陆失败
            System.out.println("请检查用户名或密码！");
        }
    }

    /**
     * 登陆的方法
     * 将用户名和密码作为参数传入本方法，再利用jdbc连接数据库查询是否有对应的数据
     *
     * @param username 用户名
     * @param password 密码
     * @return true或false
     */
    public boolean login(String username, String password) {
        //判断参数是否为null
        if (username == null || password == null) {
            //为空返回false
            return false;
        }

        String sql = "select * from user where username='" + username + "' and password='" + password + "'";

        Connection conn = null;
        Statement stmt = null;
        ResultSet rs = null;
        try {
            //创建连接
            conn = JDBCUtils.getConnection();
            //获取执行sql的对象
            stmt = conn.createStatement();
            //执行sql语句
            rs = stmt.executeQuery(sql);
            //判断结果，如果有下一行就返回true，没有返回false
            return rs.next();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            //释放资源
            JDBCUtils.close(rs, stmt, conn);
        }
        return false;
    }
}