更新
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<?php
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namespace app\service;
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/**
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* 从常见文档格式提取纯文本，供 Dify 等不支持 file 附件的接口使用。
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*/
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class DocumentTextService
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{
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private const MAX_CHARS = 12000;
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/** @var string|null 最近一次 extract 失败原因（供上层展示） */
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private static ?string $lastFailure = null;
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public static function extract(string $path, string $mime = '', string $filename = ''): ?string
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{
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self::$lastFailure = null;
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if (!is_file($path) || !is_readable($path)) {
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self::$lastFailure = 'file_unreadable';
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return null;
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}
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$ext = strtolower(pathinfo($filename ?: $path, PATHINFO_EXTENSION));
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$mime = strtolower($mime);
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$text = match (true) {
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in_array($ext, ['txt', 'md'], true) || str_starts_with($mime, 'text/') => self::readPlainText($path),
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$ext === 'docx' || str_contains($mime, 'wordprocessingml') => self::extractDocx($path),
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$ext === 'pdf' || str_contains($mime, 'pdf') => self::extractPdf($path),
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default => null,
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};
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if ($text === null) {
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return null;
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}
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$text = self::normalize($text);
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if ($text === '') {
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if (self::$lastFailure === null) {
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self::$lastFailure = 'empty_content';
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}
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return null;
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}
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return mb_substr($text, 0, self::MAX_CHARS);
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}
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public static function unsupportedReason(string $filename, string $mime = ''): string
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{
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$ext = strtolower(pathinfo($filename, PATHINFO_EXTENSION));
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if (self::$lastFailure === 'exec_disabled') {
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return 'PHP 禁用了 exec 函数，无法调用 pdftotext。请在 php.ini 的 disable_functions 中移除 exec';
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}
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if (self::$lastFailure === 'pdftotext_missing') {
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return '未找到 pdftotext 命令。请在**运行 PHP 的服务器**（不是 Dify 容器）执行：apt install poppler-utils';
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}
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if (self::$lastFailure === 'pdftotext_failed') {
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return 'pdftotext 执行失败，请检查 PDF 是否损坏或 uploads 目录是否可读';
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}
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if (self::$lastFailure === 'empty_content' && ($ext === 'pdf' || str_contains($mime, 'pdf'))) {
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return 'PDF 未提取到文字，可能是扫描版图片 PDF，请改用可复制文字的 PDF 或粘贴文字';
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}
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if ($ext === 'doc' || str_contains($mime, 'msword')) {
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return '旧版 .doc 暂不支持自动解析，请另存为 .docx 或复制文字发送';
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}
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if ($ext === 'pdf' || str_contains($mime, 'pdf')) {
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return 'PDF 文字提取失败，请在运行 PHP 的服务器安装 poppler-utils（pdftotext）';
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}
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if (!class_exists(\ZipArchive::class) && ($ext === 'docx' || str_contains($mime, 'wordprocessingml'))) {
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return 'PHP 未启用 zip 扩展，无法解析 .docx，请安装 php-zip';
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}
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return '未能提取文档文字，请改用 .txt / .docx 或粘贴文字内容';
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}
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private static function readPlainText(string $path): ?string
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{
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$content = @file_get_contents($path);
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if ($content === false) {
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return null;
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}
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if (!mb_check_encoding($content, 'UTF-8')) {
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$content = mb_convert_encoding($content, 'UTF-8', 'GB18030,UTF-8,ASCII');
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}
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return $content;
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}
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private static function extractDocx(string $path): ?string
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{
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if (!class_exists(\ZipArchive::class)) {
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return null;
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}
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$zip = new \ZipArchive();
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if ($zip->open($path) !== true) {
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return null;
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}
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$xml = $zip->getFromName('word/document.xml');
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$zip->close();
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if (!$xml) {
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return null;
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}
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$xml = preg_replace('/<w:tab[^>]*\/>/', "\t", $xml);
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$xml = preg_replace('/<\/w:p>/', "\n", $xml);
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$xml = preg_replace('/<\/w:tr>/', "\n", $xml);
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$text = strip_tags($xml);
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return html_entity_decode($text, ENT_QUOTES | ENT_XML1, 'UTF-8');
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}
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private static function extractPdf(string $path): ?string
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{
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if (!function_exists('exec')) {
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self::$lastFailure = 'exec_disabled';
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return null;
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}
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$binary = self::resolvePdftotextBinary();
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if ($binary === null) {
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self::$lastFailure = 'pdftotext_missing';
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return null;
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}
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$out = tempnam(sys_get_temp_dir(), 'pdftxt_');
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if (!$out) {
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self::$lastFailure = 'pdftotext_failed';
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return null;
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}
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$cmd = escapeshellarg($binary) . ' -enc UTF-8 -layout '
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. escapeshellarg($path) . ' ' . escapeshellarg($out) . ' 2>&1';
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exec($cmd, $_, $code);
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$text = ($code === 0 && is_file($out)) ? @file_get_contents($out) : false;
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@unlink($out);
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if ($text === false) {
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self::$lastFailure = 'pdftotext_failed';
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return null;
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}
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return $text;
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}
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/**
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* PHP-FPM 进程的 PATH 常不含 /usr/bin，需显式探测可执行文件路径。
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*/
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private static function resolvePdftotextBinary(): ?string
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{
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$candidates = [
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'/usr/bin/pdftotext',
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'/usr/local/bin/pdftotext',
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'pdftotext',
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];
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foreach ($candidates as $bin) {
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if (str_starts_with($bin, '/')) {
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if (is_executable($bin)) {
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return $bin;
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}
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continue;
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}
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if (self::commandExists($bin)) {
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return $bin;
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}
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}
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return null;
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}
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private static function commandExists(string $command): bool
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{
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if (!function_exists('exec')) {
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return false;
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}
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$check = stripos(PHP_OS, 'WIN') === 0 ? 'where' : 'command -v';
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exec($check . ' ' . escapeshellarg($command) . ' 2>/dev/null', $output, $code);
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return $code === 0 && !empty($output);
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}
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private static function normalize(string $text): string
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{
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$text = str_replace(["\r\n", "\r"], "\n", $text);
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$text = preg_replace("/[ \t]+\n/", "\n", $text);
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$text = preg_replace("/\n{3,}/", "\n\n", $text);
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return trim($text);
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}
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}
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