Ubuntu
213 lines
7.8 KiB
Python
213 lines
7.8 KiB
Python
"""
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站点提取策略化重构（v2）
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========================
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将散落在 crawl.py / universal_crawl.py 中的站点特判逻辑收敛为「策略注册表」，
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接口设计借鉴 crawl4ai 的 ContentScrapingStrategy(ABC) 思想。
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双轨调度：
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- 轨A（Legacy）：调用方现有的 if-else 站点特判，逐行保留，不删除
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- 轨B（Strategy）：本文件中的策略链，每个策略类内部逻辑 = 现有代码「原样搬迁」
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- 优先级由 STRATEGY_FIRST_DOMAINS 配置决定：
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- 默认空集：全部走旧逻辑（轨A），策略链仅作未来兜底
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- 白名单命中：策略链优先（轨B），质量不达标自动回退旧逻辑（轨A）
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"""
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from abc import ABC, abstractmethod
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from typing import Optional
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import re
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from bs4 import BeautifulSoup
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from .crawl import (
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extract_title_from_html,
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html_to_markdown,
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is_spa_site,
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convert_spa_html_to_markdown,
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)
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# 试点白名单：命中这些域名的站点「新策略优先」，质量不达标回退旧逻辑
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STRATEGY_FIRST_DOMAINS = {"juejin.cn", "csdn.net"} # 试点：命中域名策略链优先，质量不达标自动回退旧逻辑；测试后改回 set()
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# 质量门控：Markdown 最短长度（复用现有「内容过短」经验值 300）
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MIN_CONTENT_CHARS = 300
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FALLBACK_TITLE = "未获取到标题"
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class SiteExtractor(ABC):
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"""站点提取策略基类。每个策略类内部逻辑 = 现有代码原样搬迁，行为零改动。"""
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name: str = "generic"
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@abstractmethod
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def match(self, url: str) -> bool:
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"""URL 是否命中该站点"""
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def needs_browser(self, url: str) -> bool:
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"""是否需要浏览器渲染（Playwright）"""
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return False
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def extract_title(self, html: str, url: str) -> Optional[str]:
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"""站点专用标题提取；返回 None 时由 run_extractor 回退通用提取"""
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return None
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def extract_content_html(self, html: str, url: str) -> str:
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"""提取正文容器 HTML；未命中选择器时返回原 HTML"""
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return html
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def filter_images(self, images: list, url: str) -> list:
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"""过滤站点 UI 图标等噪音图片"""
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return images
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def to_markdown(self, content_html: str, url: str, images: list) -> str:
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"""将正文容器 HTML 转为 Markdown"""
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return html_to_markdown(content_html, url)
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class JuejinExtractor(SiteExtractor):
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"""掘金：requests 返回混淆代码必须浏览器渲染；正文 article.article"""
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name = "juejin"
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def match(self, url: str) -> bool:
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return 'juejin.cn' in url
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def needs_browser(self, url: str) -> bool:
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return True
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def extract_title(self, html: str, url: str) -> Optional[str]:
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# 原样搬迁 universal_crawl._extract_juejin_title
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match = re.search(r'<title[^>]*>(.*?)</title>', html, re.IGNORECASE | re.DOTALL)
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if match:
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title = match.group(1).strip()
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# 去掉 " - 掘金" 后缀
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title = re.sub(r'\s*[-–—]\s*掘金\s*$', '', title, flags=re.IGNORECASE).strip()
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if len(title) > 5:
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return title
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return None
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def extract_content_html(self, html: str, url: str) -> str:
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# 原样搬迁 universal_crawl._extract_juejin_content
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soup = BeautifulSoup(html, 'lxml')
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# 优先使用 article.article
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container = soup.select_one('article.article')
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if not container:
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# fallback 到 .article-viewer
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container = soup.select_one('.article-viewer')
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if not container:
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# 再 fallback 到 #article-root
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container = soup.select_one('#article-root')
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if container:
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return str(container)
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return html
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class CsdnExtractor(SiteExtractor):
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"""CSDN：正文 #content_views / .article_content；过滤 csdnimg UI 图标"""
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name = "csdn"
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def match(self, url: str) -> bool:
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return 'csdn.net' in url or 'csdn.com' in url
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def extract_title(self, html: str, url: str) -> Optional[str]:
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# 原样搬迁 universal_crawl._extract_csdn_title
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match = re.search(r'<title[^>]*>(.*?)</title>', html, re.IGNORECASE | re.DOTALL)
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if match:
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title = match.group(1).strip()
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# 去掉 " - CSDN博客" / "-CSDN博客" 后缀
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title = re.sub(r'\s*[-–—]?\s*CSDN博客\s*$', '', title, flags=re.IGNORECASE).strip()
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if len(title) > 5:
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return title
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return None
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def extract_content_html(self, html: str, url: str) -> str:
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# 原样搬迁 universal_crawl._extract_csdn_content
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soup = BeautifulSoup(html, 'lxml')
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# 优先使用 #content_views（CSDN 正文主容器）
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container = soup.select_one('#content_views')
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if not container:
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# fallback 到 .article_content
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container = soup.select_one('.article_content')
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if container:
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return str(container)
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return html
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def filter_images(self, images: list, url: str) -> list:
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# 原样搬迁 universal_crawl._filter_csdn_images
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filtered = []
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skip_patterns = [
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'newHeart2023',
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'tobarCollect',
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'tobarCollection',
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'copyright',
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'avatar',
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'blogv2/dist/pc/img',
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]
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for img in images:
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img_url = img.original_url.lower()
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if any(p in img_url for p in skip_patterns):
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continue
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filtered.append(img)
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return filtered
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class GenericExtractor(SiteExtractor):
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"""通用兜底：不做站点特判，复刻旧逻辑的通用分支（含 SPA 判断）"""
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name = "generic"
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def match(self, url: str) -> bool:
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return True
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def to_markdown(self, content_html: str, url: str, images: list) -> str:
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if is_spa_site(content_html):
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return convert_spa_html_to_markdown(content_html, images, url)
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return html_to_markdown(content_html, url)
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# 策略注册表：有序列表，先匹配先命中；GenericExtractor 永远兜底
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SITE_EXTRACTORS = [
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JuejinExtractor(),
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CsdnExtractor(),
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GenericExtractor(),
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]
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def get_extractor_for_url(url: str) -> Optional[SiteExtractor]:
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"""返回第一个匹配的策略；GenericExtractor 恒匹配（兜底）"""
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for extractor in SITE_EXTRACTORS:
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if extractor.match(url):
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return extractor
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return None
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def is_strategy_first(url: str) -> bool:
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"""url 是否命中试点白名单（新策略优先，失败回退旧逻辑）"""
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return any(domain in url for domain in STRATEGY_FIRST_DOMAINS)
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class ExtractorResult:
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"""策略链输出，与旧逻辑 _legacy_extract 返回 (title, markdown, images) 同构"""
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__slots__ = ("title", "markdown", "images")
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def __init__(self, title: str, markdown: str, images: list):
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self.title = title
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self.markdown = markdown
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self.images = images
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def run_extractor(extractor: SiteExtractor, url: str, html: str, images: list) -> ExtractorResult:
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"""执行策略链：专用标题 → 通用标题降级 → 图片过滤 → 正文容器 → Markdown"""
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title = extractor.extract_title(html, url) or extract_title_from_html(html) or FALLBACK_TITLE
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filtered_images = extractor.filter_images(images, url)
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content_html = extractor.extract_content_html(html, url)
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markdown = extractor.to_markdown(content_html, url, filtered_images)
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return ExtractorResult(title=title, markdown=markdown, images=filtered_images)
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def is_strategy_success(result: ExtractorResult, min_chars: int = MIN_CONTENT_CHARS) -> bool:
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"""质量门控：标题有效 + Markdown 长度达标（复用现有「内容过短」经验值）"""
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if not result.title or result.title == FALLBACK_TITLE:
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return False
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if len((result.markdown or "").strip()) < min_chars:
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return False
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return True
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