使用PHP IMAP高效筛选带附件的邮件

public function mail_list(){
  $mbox = $this->input->get("boxname");
  $mbox = (isset($mbox))? $mbox : "INBOX";
  $mails = $this->connect_mailserver($mbox); // 连接IMAP服务器
  if($mails) {
    $mailno_arr = array();
    $mailno_arr_tmp = imap_sort($mails, SORTDATE, 1); // 假设已排序，获取邮件编号
    // 遍历前15封邮件进行处理
    for($i=0; $i<15; $i++) {
      $mail_uid = $mailno_arr_tmp[$i]; // 邮件UID
      // !!! 性能瓶颈：下载整个邮件体进行字符串搜索
      $body = imap_body($mails, $mail_uid);
      $has_attachments = (strpos($body, 'Content-Disposition: attachment') !== false) ? "1" : "0";
      $arr = array(
        "no" => $mail_uid,
        "attachments" => $has_attachments
      );
      array_push($mailno_arr, $arr);
    }
    $data['mailno_arr'] = $mailno_arr;
  }
  imap_close($mails);
  $this->load->view('mailbox/mail_list_v', $data);
}

public function connect_mailserver($mbox="") {
  $mailserver = $this->mailserver;
  $host = "{" . $mailserver . ":143/imap/novalidate-cert}$mbox";
  $user_id = $this->user_id;
  $user_pwd = $this->user_pwd;
  return @imap_open($host, $user_id, $user_pwd);
}

<?php

class Mailbox_Controller extends CI_Controller { // 假设这是CodeIgniter控制器

    private $mailserver = "your.mailserver.com"; // 邮件服务器地址
    private $user_id = "your_username"; // 用户名
    private $user_pwd = "your_password"; // 密码

    public function mail_list(){
        $mbox_name = $this->input->get("boxname");
        $mbox_name = (isset($mbox_name)) ? $mbox_name : "INBOX";
        $mails = $this->connect_mailserver($mbox_name);

        $mail_list_data = array();

        if($mails) {
            // 获取所有邮件的UID，通常imap_sort返回的是UIDs
            // 注意：imap_sort返回的是邮件序列号，如果需要UID，可以使用imap_uid
            $mail_sequence_numbers = imap_sort($mails, SORTDATE, 1); // 假设按日期降序排列

            // 限制处理前15封邮件，与原需求保持一致
            $limit = min(count($mail_sequence_numbers), 15);

            for($i = 0; $i < $limit; $i++) {
                $mail_seq_num = $mail_sequence_numbers[$i];
                $has_attachments = $this->check_for_attachments($mails, $mail_seq_num);

                $mail_list_data[] = array(
                    "no" => $mail_seq_num,
                    "attachments" => $has_attachments ? "1" : "0"
                );
            }
        }
        imap_close($mails);
        $data['mailno_arr'] = $mail_list_data;
        $this->load->view('mailbox/mail_list_v', $data);
    }

    /**
     * 连接IMAP服务器
     */
    public function connect_mailserver($mbox_name = "") {
        $host = "{" . $this->mailserver . ":143/imap/novalidate-cert}$mbox_name";
        return @imap_open($host, $this->user_id, $this->user_pwd);
    }

    /**
     * 递归检查邮件结构中是否存在附件
     * @param resource $imap_stream IMAP连接资源
     * @param int $mail_seq_num 邮件序列号
     * @return bool 如果存在附件则返回true，否则返回false
     */
    private function check_for_attachments($imap_stream, $mail_seq_num) {
        $structure = imap_fetchstructure($imap_stream, $mail_seq_num);

        if (!$structure) {
            return false; // 无法获取结构
        }

        // 辅助函数：递归遍历邮件部分
        $check_part = function($part) use (&$check_part) {
            // 检查 disposition 是否为 attachment
            if (isset($part->disposition) && strtolower($part->disposition) == 'attachment') {
                return true;
            }
            // 检查 parameters 中是否有 filename，这通常也指示附件
            if (isset($part->parameters)) {
                foreach ($part->parameters as $param) {
                    if (strtolower($param->attribute) == 'filename') {
                        return true;
                    }
                }
            }
            // 如果是多部分邮件，递归检查其子部分
            if (isset($part->parts) && is_array($part->parts)) {
                foreach ($part->parts as $sub_part) {
                    if ($check_part($sub_part)) {
                        return true;
                    }
                }
            }
            return false;
        };

        // 从主结构开始检查
        return $check_part($structure);
    }
}
?>