77 lines
1.9 KiB
PHP
77 lines
1.9 KiB
PHP
<?php
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namespace app\common;
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use think\Env;
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/**
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* Unpaywall OA PDF 定位
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* @see https://unpaywall.org/products/api
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*/
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class UnpaywallService
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{
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private $email;
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private $timeout = 20;
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public function __construct()
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{
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$this->email = trim((string)Env::get('unpaywall_email', Env::get('pubmed_email', '')));
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}
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/**
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* @return string PDF 直链，找不到返回空
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*/
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public function findOaPdfUrl($doi)
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{
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$doi = trim((string)$doi);
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if ($doi === '' || $this->email === '') {
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return '';
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}
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$url = 'https://api.unpaywall.org/v2/' . rawurlencode($doi) . '?' . http_build_query([
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'email' => $this->email,
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]);
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$ch = curl_init();
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curl_setopt_array($ch, [
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CURLOPT_URL => $url,
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CURLOPT_RETURNTRANSFER => true,
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CURLOPT_TIMEOUT => $this->timeout,
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CURLOPT_SSL_VERIFYPEER => false,
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CURLOPT_HTTPHEADER => ['User-Agent: TMRjournals-Unpaywall/1.0'],
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]);
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$raw = curl_exec($ch);
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curl_close($ch);
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if (!is_string($raw) || $raw === '') {
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return '';
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}
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$json = json_decode($raw, true);
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if (!is_array($json)) {
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return '';
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}
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$best = $json['best_oa_location'] ?? [];
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if (!is_array($best)) {
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return '';
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}
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foreach (['url_for_pdf', 'url'] as $key) {
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$candidate = trim((string)($best[$key] ?? ''));
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if ($candidate !== '' && $this->looksLikePdfUrl($candidate)) {
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return $candidate;
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}
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}
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return '';
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}
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private function looksLikePdfUrl($url)
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{
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if (stripos($url, '.pdf') !== false) {
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return true;
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}
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return (bool)preg_match('#/(pdf|download|content/pdf)#i', $url);
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}
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}
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