初始提交: PDF翻译网站
功能: - 上传PDF自动翻译成中文 - 不登录可用(次数限制) - 登录后获得更多次数 - 会员等级制度(不同权益) - 智能缓存(相同文件秒出结果) - 原文译文对比查看 - 支持重新翻译(自定义要求) - 翻译历史记录 技术栈: Flask + SQLAlchemy + Bootstrap5
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services.py
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316
services.py
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"""
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PDF翻译服务模块
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"""
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import os
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import json
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import time
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import hashlib
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import threading
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from datetime import datetime, timedelta
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from pypdf import PdfReader
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from openai import OpenAI
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from flask import current_app
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# ==================== LLM客户端 ====================
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class TranslationService:
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"""翻译服务"""
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def __init__(self, config):
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self.config = config
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self.llm_config = config['LLM_CONFIG']
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self.client = OpenAI(
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api_key=self.llm_config['api_key'],
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base_url=self.llm_config['api_base'],
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)
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def translate_text(self, text, instruction=None):
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"""
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翻译文本
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Args:
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text: 待翻译文本
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instruction: 用户自定义翻译要求
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Returns:
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翻译后的文本
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"""
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system_prompt = """你是一个专业的英译中翻译专家。请遵循以下规则：
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1. 保持原文的格式和段落结构
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2. 专业术语保持准确性，必要时保留英文原文
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3. 语言流畅自然，符合中文表达习惯
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4. 不要添加任何解释或注释，只输出翻译结果"""
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user_prompt = f"""请将以下英文翻译成中文。直接输出中文翻译，不要解释。
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英文内容：
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{text}"""
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if instruction:
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user_prompt = f"""请将以下英文翻译成中文。
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用户翻译要求：{instruction}
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英文内容：
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{text}"""
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try:
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response = self.client.chat.completions.create(
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model=self.llm_config['model'],
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messages=[
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{"role": "system", "content": system_prompt},
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{"role": "user", "content": user_prompt}
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],
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max_tokens=self.llm_config['max_tokens'],
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temperature=0.3,
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timeout=self.llm_config['timeout'],
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)
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content = response.choices[0].message.content
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if content and content.strip():
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return content.strip()
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return text
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except Exception as e:
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print(f"翻译错误: {e}")
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return text
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def extract_pdf_text(self, pdf_path):
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"""提取PDF文本"""
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reader = PdfReader(pdf_path)
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pages = []
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for i, page in enumerate(reader.pages):
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text = page.extract_text()
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if text.strip():
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# 清理文本
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text = self._clean_text(text)
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pages.append({
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'page': i + 1,
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'text': text
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})
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return pages
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def _clean_text(self, text):
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"""清理文本"""
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import re
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text = re.sub(r'\n{3,}', '\n\n', text)
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text = re.sub(r' {2,}', ' ', text)
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text = re.sub(r'[\x00-\x08\x0b\x0c\x0e-\x1f]', '', text)
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return text.strip()
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def chunk_text(self, text, max_size=2000):
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"""分块"""
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paragraphs = text.split('\n\n')
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chunks = []
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current = ""
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for para in paragraphs:
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if len(current) + len(para) < max_size:
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current += para + '\n\n'
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else:
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if current:
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chunks.append(current.strip())
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current = para + '\n\n'
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if current:
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chunks.append(current.strip())
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return chunks
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def translate_pdf(self, pdf_path, output_path, instruction=None, progress_callback=None):
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"""
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翻译PDF
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Args:
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pdf_path: 输入PDF路径
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output_path: 输出路径
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instruction: 用户翻译要求
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progress_callback: 进度回调函数
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Returns:
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翻译统计信息
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"""
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pages = self.extract_pdf_text(pdf_path)
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total_pages = len(pages)
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if progress_callback:
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progress_callback(0, total_pages, "开始翻译...")
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translated_pages = []
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total_chunks = 0
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for page_data in pages:
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chunks = self.chunk_text(page_data['text'], self.llm_config['chunk_size'])
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total_chunks += len(chunks)
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translated_chunks = []
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for i, chunk in enumerate(chunks):
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translated = self.translate_text(chunk, instruction)
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translated_chunks.append(translated)
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if progress_callback:
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progress = int((i + 1) / len(chunks) * 100 / total_pages)
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progress_callback(progress, total_pages, f"翻译第{page_data['page']}页")
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translated_pages.append({
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'page': page_data['page'],
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'original': page_data['text'],
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'translated': '\n\n'.join(translated_chunks)
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})
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# 保存结果
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self._save_output(translated_pages, output_path)
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if progress_callback:
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progress_callback(100, total_pages, "翻译完成")
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return {
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'total_pages': total_pages,
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'total_chunks': total_chunks,
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'output_path': output_path
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}
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def _save_output(self, pages, output_path):
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"""保存翻译结果"""
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content = "# 英文PDF中文翻译\n\n> 自动翻译生成\n\n---\n\n"
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for page in pages:
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content += f"## 第 {page['page']} 页\n\n"
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content += page['translated'] + "\n\n---\n\n"
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with open(output_path, 'w', encoding='utf-8') as f:
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f.write(content)
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def save_comparison(self, pages, output_path):
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"""保存对比文件（原文+译文）"""
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content = "# 英文PDF翻译对比\n\n---\n\n"
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for page in pages:
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content += f"## 第 {page['page']} 页\n\n"
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content += "### 原文\n\n```\n" + page['original'] + "\n```\n\n"
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content += "### 译文\n\n" + page['translated'] + "\n\n---\n\n"
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with open(output_path, 'w', encoding='utf-8') as f:
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f.write(content)
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# ==================== 缓存服务 ====================
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class CacheService:
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"""翻译缓存服务"""
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def __init__(self, cache_dir, expire_days=30):
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self.cache_dir = cache_dir
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self.expire_days = expire_days
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if not os.path.exists(cache_dir):
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os.makedirs(cache_dir)
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def compute_hash(self, file_content):
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"""计算文件哈希"""
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return hashlib.md5(file_content).hexdigest()
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def get_cache(self, file_hash, db_model=None):
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"""
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获取缓存
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Returns:
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缓存路径或None
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"""
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cache_file = os.path.join(self.cache_dir, f"{file_hash}.md")
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if os.path.exists(cache_file):
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# 检查过期
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file_time = datetime.fromtimestamp(os.path.getmtime(cache_file))
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if datetime.now() - file_time > timedelta(days=self.expire_days):
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os.remove(cache_file)
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return None
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# 更新命中计数
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if db_model:
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cache_record = db_model.query.filter_by(file_hash=file_hash).first()
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if cache_record:
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cache_record.increment_hit()
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return cache_file
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return None
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def save_cache(self, file_hash, content):
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"""保存缓存"""
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cache_file = os.path.join(self.cache_dir, f"{file_hash}.md")
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with open(cache_file, 'w', encoding='utf-8') as f:
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f.write(content)
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return cache_file
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def check_cache_exists(self, file_hash):
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"""检查缓存是否存在"""
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cache_file = os.path.join(self.cache_dir, f"{file_hash}.md")
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return os.path.exists(cache_file)
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# ==================== 异步翻译任务 ====================
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class TranslationTask:
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"""异步翻译任务"""
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tasks = {} # 任务存储
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lock = threading.Lock()
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@classmethod
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def create_task(cls, task_id, pdf_path, output_path, config, instruction=None):
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"""创建翻译任务"""
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task = {
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'id': task_id,
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'status': 'pending',
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'progress': 0,
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'message': '等待开始',
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'output_path': output_path,
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'error': None,
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'started_at': None,
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'completed_at': None,
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}
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with cls.lock:
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cls.tasks[task_id] = task
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# 启动翻译线程
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def run_translation():
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service = TranslationService(config)
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task['status'] = 'processing'
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task['started_at'] = datetime.now().isoformat()
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def progress_callback(progress, total, message):
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with cls.lock:
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task['progress'] = progress
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task['message'] = message
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try:
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result = service.translate_pdf(
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pdf_path, output_path, instruction, progress_callback
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)
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task['status'] = 'completed'
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task['progress'] = 100
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task['message'] = '翻译完成'
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task['completed_at'] = datetime.now().isoformat()
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task['result'] = result
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except Exception as e:
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task['status'] = 'failed'
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task['error'] = str(e)
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task['message'] = f'翻译失败: {e}'
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thread = threading.Thread(target=run_translation)
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thread.start()
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return task_id
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@classmethod
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def get_task(cls, task_id):
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"""获取任务状态"""
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with cls.lock:
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return cls.tasks.get(task_id)
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@classmethod
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def update_task(cls, task_id, **kwargs):
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"""更新任务"""
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with cls.lock:
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if task_id in cls.tasks:
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cls.tasks[task_id].update(kwargs)
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