feat(jfile): 添加CORS响应头支持第三方前端下载图片

- 添加HTTP中间件为/files路径响应添加CORS响应头
- 支持Access-Control-Allow-Origin、Access-Control-Allow-Methods和Access-Control-Expose-Headers
- 添加Content-Disposition头让浏览器直接下载而不是打开图片
- 统一处理OPTIONS预检请求
- 优化性能：提前返回非目标请求

apps/jfile/app.py

@@ -1,9 +1,11 @@
 import uvicorn
-from fastapi import FastAPI
+from fastapi import FastAPI, Request
 from fastapi.staticfiles import StaticFiles
+from fastapi.responses import Response
 from file_cleaner import FileCleaner
 from settings import settings
 import asyncio
+import os
 
 app = FastAPI(
     title="www",
@@ -11,6 +13,39 @@ app = FastAPI(
     version="1.0.0"
 )
 
+# 添加中间件，为静态文件响应添加 CORS 响应头和下载头
+@app.middleware("http")
+async def add_cors_headers(request: Request, call_next):
+    # 只处理 /files 路径的请求，提前返回提高效率
+    if not request.url.path.startswith("/files"):
+        return await call_next(request)
+    
+    # 处理 OPTIONS 预检请求
+    if request.method == "OPTIONS":
+        return Response(
+            headers={
+                "Access-Control-Allow-Origin": "*",
+                "Access-Control-Allow-Methods": "GET, OPTIONS",
+                "Access-Control-Expose-Headers": "Content-Disposition"
+            }
+        )
+    
+    # 处理 GET 请求
+    response = await call_next(request)
+    
+    # 添加 CORS 响应头
+    response.headers["Access-Control-Allow-Origin"] = "*"
+    response.headers["Access-Control-Allow-Methods"] = "GET, OPTIONS"
+    response.headers["Access-Control-Expose-Headers"] = "Content-Disposition"
+    
+    # 添加 Content-Disposition 头，让浏览器下载而不是打开
+    if "Content-Disposition" not in response.headers:
+        filename = os.path.basename(request.url.path)
+        if filename:
+            response.headers["Content-Disposition"] = f'attachment; filename="{filename}"'
+    
+    return response
+
 # 挂载静态文件目录
 app.mount("/files", StaticFiles(directory="files"), name="files")