Codeigniter使用我自己的上传库复制图像文件名

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class MY_Upload extends CI_Upload {

    public function __construct()
    {
        parent::__construct();
    }

    public function copy_image_file_name($field = 'userfile', $upload_path = './uploads/')
    {
        if (isset($_FILES[$field]['name'])) {
            $file_name = $_FILES[$field]['name'];
            $file_ext = pathinfo($file_name, PATHINFO_EXTENSION);
            $new_file_name = uniqid().'.'.$file_ext;

            $config['upload_path'] = $upload_path;
            $config['file_name'] = $new_file_name;

            $this->initialize($config);

            if ($this->do_upload($field)) {
                return $new_file_name;
            } else {
                return $this->display_errors();
            }
        }
    }
}

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Your_controller extends CI_Controller {

    public function __construct()
    {
        parent::__construct();
        $this->load->library('upload');
    }

    public function upload_image()
    {
        $file_name = $this->upload->copy_image_file_name('image_field', './uploads/');
        if ($file_name) {
            // 文件上传成功，可以进行其他操作
            echo '上传成功，新文件名为：'.$file_name;
        } else {
            // 文件上传失败，处理错误信息
            echo '上传失败，错误信息：'.$this->upload->display_errors();
        }
    }
}