1

app/index.tsx

@@ -432,7 +432,9 @@ export default function HomeScreen() {
             <Ionicons name="search" size={14} color="#999" />
             <Text style={styles.searchPlaceholder}>搜索视频、UP主...</Text>
           </TouchableOpacity>
-          <DownloadProgressBtn onPress={() => router.push('/downloads' as any)} />
+          <DownloadProgressBtn
+            onPress={() => router.push("/downloads" as any)}
+          />
         </Animated.View>
 
         <View style={styles.tabRow}>

hooks/useDownload.ts

@@ -4,34 +4,28 @@ import { AppState } from 'react-native';
 import { useDownloadStore } from '../store/downloadStore';
 import { getPlayUrlForDownload } from '../services/bilibili';
 
-// 模块级进度节流
 const lastReportedProgress: Record<string, number> = {};
 
 const QUALITY_LABELS: Record<number, string> = {
-  16: '360P',
-  32: '480P',
-  64: '720P',
-  80: '1080P',
-  112: '1080P+',
-  116: '1080P60',
+  16: '360P', 32: '480P', 64: '720P',
+  80: '1080P', 112: '1080P+', 116: '1080P60',
 };
 
 /** 等待 App 回到前台 */
 function waitForActive(): Promise<void> {
   return new Promise((resolve) => {
-    if (AppState.currentState === 'active') {
-      resolve();
-      return;
-    }
-    const sub = AppState.addEventListener('change', (nextState) => {
-      if (nextState === 'active') {
-        sub.remove();
-        resolve();
-      }
+    if (AppState.currentState === 'active') { resolve(); return; }
+    const sub = AppState.addEventListener('change', (s) => {
+      if (s === 'active') { sub.remove(); resolve(); }
     });
   });
 }
 
+/** 当前是否在后台 */
+function isBackground() {
+  return AppState.currentState !== 'active';
+}
+
 /** 读取本地文件实际大小 */
 async function readFileSize(uri: string): Promise<number | undefined> {
   try {
@@ -44,21 +38,14 @@ async function readFileSize(uri: string): Promise<number | undefined> {
 export function useDownload() {
   const { tasks, addTask, updateTask, removeTask } = useDownloadStore();
 
-  function taskKey(bvid: string, qn: number) {
-    return `${bvid}_${qn}`;
-  }
-
+  function taskKey(bvid: string, qn: number) { return `${bvid}_${qn}`; }
   function localPath(bvid: string, qn: number) {
     return `${FileSystem.documentDirectory}${bvid}_${qn}.mp4`;
   }
 
   async function startDownload(
-    bvid: string,
-    cid: number,
-    qn: number,
-    qdesc: string,
-    title: string,
-    cover: string,
+    bvid: string, cid: number, qn: number,
+    qdesc: string, title: string, cover: string,
   ) {
     const key = taskKey(bvid, qn);
     if (tasks[key]?.status === 'downloading') return;
@@ -66,11 +53,25 @@ export function useDownload() {
     addTask(key, {
       bvid, title, cover, qn,
       qdesc: qdesc || QUALITY_LABELS[qn] || String(qn),
-      status: 'downloading',
-      progress: 0,
-      createdAt: Date.now(),
+      status: 'downloading', progress: 0, createdAt: Date.now(),
     });
 
+    // 最多重新拉取 URL 并重试一次（应对后台时 URL 过期的情况）
+    for (let attempt = 0; attempt < 2; attempt++) {
+      const success = await attemptDownload(key, bvid, cid, qn);
+      if (success !== 'retry') return;
+      // 需要重试：重新拉取 URL
+      updateTask(key, { status: 'downloading', progress: 0 });
+      lastReportedProgress[key] = -1;
+    }
+
+    updateTask(key, { status: 'error', error: '下载失败，请重试' });
+  }
+
+  /** 执行一次下载尝试。返回 'done' | 'error' | 'retry' */
+  async function attemptDownload(
+    key: string, bvid: string, cid: number, qn: number,
+  ): Promise<'done' | 'error' | 'retry'> {
     try {
       const [url, buvid3, sessdata] = await Promise.all([
         getPlayUrlForDownload(bvid, cid, qn),
@@ -86,8 +87,7 @@ export function useDownload() {
       const headers = {
         Referer: 'https://www.bilibili.com',
         Origin: 'https://www.bilibili.com',
-        'User-Agent':
-          'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36',
+        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36',
         ...(cookies.length > 0 && { Cookie: cookies.join('; ') }),
       };
 
@@ -104,52 +104,69 @@ export function useDownload() {
 
       const resumable = FileSystem.createDownloadResumable(url, dest, { headers }, progressCallback);
 
-      // ── 后台暂停 / 前台续传 ──
-      let pausedByBackground = false;
-      const appStateSub = AppState.addEventListener('change', async (nextState) => {
-        if ((nextState === 'background' || nextState === 'inactive') && !pausedByBackground) {
-          pausedByBackground = true;
+      // 进入后台时主动暂停，抢在 OS 断连之前
+      let bgPaused = false;
+      const appStateSub = AppState.addEventListener('change', async (state) => {
+        if ((state === 'background' || state === 'inactive') && !bgPaused) {
+          bgPaused = true;
           try { await resumable.pauseAsync(); } catch {}
         }
       });
 
-      let result = await resumable.downloadAsync();
+      let result: FileSystem.DownloadResult | null = null;
 
-      // 如果是因为进入后台被暂停（result 为 null 或抛出连接中断），等回前台续传
-      if (!result?.uri && pausedByBackground) {
-        await waitForActive();
-        pausedByBackground = false;
+      try {
+        result = await resumable.downloadAsync();
+      } catch (e: any) {
+        // downloadAsync 抛出：多为后台断连（connection abort）或被 pauseAsync 中断
+        if (!isBackground() && !bgPaused) {
+          // 真实网络错误，非后台原因
+          appStateSub.remove();
+          delete lastReportedProgress[key];
+          const msg = e?.message ?? '下载失败';
+          updateTask(key, { status: 'error', error: msg.length > 40 ? msg.slice(0, 40) + '...' : msg });
+          return 'error';
+        }
+        // 后台引发的中断，走下面的续传逻辑
+        result = null;
+      } finally {
+        appStateSub.remove();
+      }
+
+      // ── 续传逻辑：result 为 null 说明被暂停或中断 ──
+      if (!result?.uri) {
+        // 等 App 回到前台
+        if (isBackground()) await waitForActive();
+
+        // 尝试从断点续传
         try {
           result = await resumable.resumeAsync();
         } catch {
           result = null;
         }
+
+        // 续传仍失败（URL 可能过期），通知上层重试
+        if (!result?.uri) {
+          delete lastReportedProgress[key];
+          return 'retry';
+        }
       }
 
-      appStateSub.remove();
+      // ── 下载完成 ──
       delete lastReportedProgress[key];
-
-      if (result?.uri) {
-        const fileSize = await readFileSize(result.uri);
-        updateTask(key, {
-          status: 'done', progress: 1, localUri: result.uri,
-          ...(fileSize ? { fileSize } : {}),
-        });
-      } else {
-        updateTask(key, { status: 'error', error: '下载失败' });
-      }
+      const fileSize = await readFileSize(result.uri);
+      updateTask(key, {
+        status: 'done', progress: 1, localUri: result.uri,
+        ...(fileSize ? { fileSize } : {}),
+      });
+      return 'done';
 
     } catch (e: any) {
       delete lastReportedProgress[key];
       console.error('[Download] failed:', e);
-
-      // 连接中断 + 已被后台暂停 → 不报错，等回前台后让用户手动重试即可
-      const isConnectionAbort = (e?.message ?? '').includes('connection a');
-      const msg = isConnectionAbort ? '已暂停，返回应用后可重试' : (e?.message ?? '下载失败');
-      updateTask(key, {
-        status: 'error',
-        error: msg.length > 40 ? msg.slice(0, 40) + '...' : msg,
-      });
+      const msg = e?.message ?? '下载失败';
+      updateTask(key, { status: 'error', error: msg.length > 40 ? msg.slice(0, 40) + '...' : msg });
+      return 'error';
     }
   }