python(39) : 浅蓝色主题AI问答服务(含界面)

流式响应

多轮对话

1.文件结构

├── app.py 
│
├── 📁 templates/                # 前端模板目录
│   ├── index.html              # 主页面HTML文件
│   ├── marked.min.js   

2.python依赖

Flask==2.3.3
Flask-CORS==4.0.0
openai==1.3.0
langchain==0.1.0
langchain-community==0.0.10
langchain-core==0.1.0
langchain-openai==0.0.5
python-dotenv==1.0.0

3.app.py

import json
import os
from typing import Generator

from dotenv import load_dotenv
from flask import Flask, request, jsonify, render_template, send_file
from flask_cors import CORS
from langchain.memory import ConversationBufferWindowMemory
from langchain_core.messages import HumanMessage, AIMessage
from langchain_openai import ChatOpenAI

# 加载环境变量
load_dotenv('config.env')

app = Flask(__name__)
CORS(app)

# 配置
DASHSCOPE_API_KEY = os.getenv('DASHSCOPE_API_KEY', 'your-dashscope-api-key')

# 初始化模型
llm = ChatOpenAI(
    model="qwen-plus",
    openai_api_key=DASHSCOPE_API_KEY,
    openai_api_base="https://dashscope.aliyuncs.com/compatible-mode/v1",
    temperature=0.7,
    streaming=True
)

# 内存管理 - 使用滑动窗口保持最近10轮对话
memory = ConversationBufferWindowMemory(k=10, return_messages=True)

# 存储用户会话
user_sessions = {}


def get_user_memory(user_id: str):
    """获取或创建用户的内存"""
    if user_id not in user_sessions:
        user_sessions[user_id] = ConversationBufferWindowMemory(k=10, return_messages=True)
    return user_sessions[user_id]


def generate_streaming_response(user_id: str, question: str) -> Generator[str, None, None]:
    """生成流式响应"""
    try:
        # 获取用户内存
        user_memory = get_user_memory(user_id)

        # 获取历史对话
        history = user_memory.chat_memory.messages

        # 构建消息列表
        messages = []
        for msg in history:
            if isinstance(msg, HumanMessage):
                messages.append({"role": "user", "content": msg.content})
            elif isinstance(msg, AIMessage):
                messages.append({"role": "assistant", "content": msg.content})

        # 添加当前问题
        messages.append({"role": "user", "content": question})

        # 调用通义千问Plus
        response = llm.stream(messages)

        full_response = ""
        for chunk in response:
            if hasattr(chunk, 'content') and chunk.content:
                content = chunk.content
                full_response += content
                yield f"data: {json.dumps({'content': content, 'done': False}, ensure_ascii=False)}\n\n"

        # 保存到内存
        user_memory.chat_memory.add_user_message(question)
        user_memory.chat_memory.add_ai_message(full_response)

        # 发送完成信号
        sources = [
            {"id": 1, "title": "通义千问Plus", "url": "https://dashscope.aliyuncs.com/"},
            {"id": 2, "title": "LangChain上下文管理", "url": "https://python.langchain.com/"}
        ]
        if '吃饭' not in question:
            sources = None
        yield f"data: {json.dumps({'content': '', 'done': True, 'sources': sources}, ensure_ascii=False)}\n\n"

    except Exception as e:
        error_msg = f"生成回答时出错: {str(e)}"
        yield f"data: {json.dumps({'content': error_msg, 'done': True, 'error': True}, ensure_ascii=False)}\n\n"

    print('问题回答完成')

@app.route('/')
def index():
    """主页面"""
    return render_template('index.html')

@app.route('/marked.min.js')
def markedjs():
    return render_template('marked.min.js')


@app.route('/api/chat', methods=['POST'])
def chat():
    """处理聊天请求"""
    try:
        data = request.get_json()
        question = data.get('question', '').strip()
        user_id = data.get('user_id', 'default_user')

        if not question:
            return jsonify({'error': '问题不能为空'}), 400

        # 生成流式响应
        def generate():
            for chunk in generate_streaming_response(user_id, question):
                yield chunk

        return app.response_class(
            generate(),
            mimetype='text/plain',
            headers={
                'Cache-Control': 'no-cache',
                'Connection': 'keep-alive',
                'Content-Type': 'text/event-stream',
            }
        )

    except Exception as e:
        return jsonify({'error': f'服务器错误: {str(e)}'}), 500


@app.route('/api/clear_history', methods=['POST'])
def clear_history():
    """清除对话历史"""
    try:
        data = request.get_json()
        user_id = data.get('user_id', 'default_user')

        if user_id in user_sessions:
            user_sessions[user_id].clear()

        return jsonify({'message': '历史记录已清除'})

    except Exception as e:
        return jsonify({'error': f'清除历史记录失败: {str(e)}'}), 500


@app.route('/api/history', methods=['GET'])
def get_history():
    """获取对话历史"""
    try:
        user_id = request.args.get('user_id', 'default_user')
        user_memory = get_user_memory(user_id)

        history = []
        for msg in user_memory.chat_memory.messages:
            if isinstance(msg, HumanMessage):
                history.append({'type': 'user', 'content': msg.content})
            elif isinsta