AI 生成: 基于 Flask 的 AI 免费对话应用，后端集成豆包（Doubao）和 DeepSeek，通过 SSE 实时推送消息，前端提供简洁的聊天界面。

app.py

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+# -*- coding: utf-8 -*-
+"""
+AI Free Chat - Flask 主应用
+提供聊天页面和 SSE 流式接口
+"""
+import os
+import json
+from flask import Flask, render_template, request, Response, stream_with_context
+from dotenv import load_dotenv
+
+from services.doubao import DoubaoService
+from services.deepseek import DeepSeekService
+
+# 加载环境变量
+load_dotenv()
+
+app = Flask(__name__)
+
+# 初始化服务
+services = {
+    "doubao": DoubaoService(),
+    "deepseek": DeepSeekService(),
+}
+
+
+@app.route("/")
+def index():
+    """渲染聊天页面"""
+    return render_template("index.html")
+
+
+@app.route("/api/chat", methods=["POST"])
+def chat():
+    """
+    SSE 流式聊天接口
+    请求体: { provider: 'doubao'|'deepseek', messages: [{role, content}] }
+    响应: text/event-stream
+    """
+    data = request.get_json(silent=True) or {}
+    provider = data.get("provider", "deepseek")
+    messages = data.get("messages", [])
+
+    if provider not in services:
+        return Response(
+            f"data: {json.dumps({'error': '未知的 provider'})}\n\n",
+            mimetype="text/event-stream",
+        )
+
+    if not messages:
+        return Response(
+            f"data: {json.dumps({'error': 'messages 不能为空'})}\n\n",
+            mimetype="text/event-stream",
+        )
+
+    service = services[provider]
+
+    def generate():
+        """生成 SSE 事件流"""
+        try:
+            for chunk in service.stream_chat(messages):
+                payload = json.dumps({"content": chunk}, ensure_ascii=False)
+                yield f"data: {payload}\n\n"
+            yield "data: [DONE]\n\n"
+        except Exception as e:  # noqa: BLE001
+            err = json.dumps({"error": str(e)}, ensure_ascii=False)
+            yield f"data: {err}\n\n"
+
+    headers = {
+        "Cache-Control": "no-cache",
+        "X-Accel-Buffering": "no",
+        "Connection": "keep-alive",
+    }
+    return Response(
+        stream_with_context(generate()),
+        mimetype="text/event-stream",
+        headers=headers,
+    )
+
+
+if __name__ == "__main__":
+    port = int(os.getenv("PORT", "5000"))
+    app.run(host="0.0.0.0", port=port, debug=True, threaded=True)