feat(download): 后端支持 Range 分块; 前端引入多线程分块下载加速音频加载

app.py

@@ -28,6 +28,7 @@ import tjaf
 
 from functools import wraps
 from flask import Flask, g, jsonify, render_template, request, abort, redirect, session, flash, make_response, send_from_directory
+import mimetypes
 from flask_caching import Cache
 from flask_session import Session
 from flask_wtf.csrf import CSRFProtect, generate_csrf, CSRFError
@@ -786,7 +787,33 @@ def send_assets(ref):
 
 @app.route(basedir + "songs/<path:ref>")
 def send_songs(ref):
-    return cache_wrap(flask.send_from_directory("public/songs", ref), 604800)
+    path = os.path.normpath(os.path.join("public/songs", ref))
+    if not os.path.isfile(path):
+        return abort(404)
+    rng = flask.request.headers.get("Range")
+    if rng and re.match(r"^bytes=\d+-\d*$", rng):
+        size = os.path.getsize(path)
+        m = re.match(r"bytes=(\d+)-(\d*)", rng)
+        start = int(m.group(1))
+        end = int(m.group(2) or size - 1)
+        start = max(0, start)
+        end = min(size - 1, end)
+        with open(path, "rb") as f:
+            f.seek(start)
+            data = f.read(end - start + 1)
+        mime = mimetypes.guess_type(path)[0] or "application/octet-stream"
+        resp = flask.Response(data, 206, mimetype=mime)
+        resp.headers["Content-Range"] = f"bytes {start}-{end}/{size}"
+        resp.headers["Accept-Ranges"] = "bytes"
+        resp.headers["Cache-Control"] = "public, max-age=604800, s-maxage=604800"
+        resp.headers["CDN-Cache-Control"] = "max-age=604800"
+        return resp
+    resp = flask.send_from_directory("public/songs", ref)
+    res = flask.make_response(resp)
+    res.headers["Accept-Ranges"] = "bytes"
+    res.headers["Cache-Control"] = "public, max-age=604800, s-maxage=604800"
+    res.headers["CDN-Cache-Control"] = "max-age=604800"
+    return res
 
 @app.route(basedir + "manifest.json")
 def send_manifest():