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uniapp/Google Chrome/Form1.cs

@@ -1,5 +1,6 @@
 using System.Text.Json;
 using System.Text.Json.Nodes;
+using System.Text.RegularExpressions;
 using Microsoft.Web.WebView2.Core;
 
 namespace WinFormsApp3
@@ -29,6 +30,9 @@ namespace WinFormsApp3
         private CancellationTokenSource? downloadCts;
         private bool hooksAttached;
 
+        /// <summary>批量下载时用于识别“用户按了取消”，直接中止后续条目。</summary>
+        private bool downloadWasCanceled;
+
         public Form1()
         {
             InitializeComponent();
@@ -283,6 +287,34 @@ namespace WinFormsApp3
             }
         }
 
+        /// <summary>
+        /// 把 WebView2 调用封送回 UI 线程执行：CoreWebView2 是 COM 接口，
+        /// 从线程池线程（如截图预览的后台任务）直接调会永久卡死，必须先封送。
+        /// </summary>
+        private async Task<T> OnUiAsync<T>(Func<Task<T>> action)
+        {
+            var tcs = new TaskCompletionSource<T>(TaskCreationOptions.RunContinuationsAsynchronously);
+            PreviewLog.Write($"OnUiAsync 排队 {action.Method.Name}");
+            try
+            {
+                BeginInvoke(new Action(async () =>
+                {
+                    try
+                    {
+                        T r = await action();
+                        PreviewLog.Write($"OnUiAsync 完成 {action.Method.Name}");
+                        tcs.SetResult(r);
+                    }
+                    catch (Exception ex) { tcs.SetException(ex); }
+                }));
+            }
+            catch (Exception ex)
+            {
+                tcs.SetException(ex);
+            }
+            return await tcs.Task;
+        }
+
         /// <summary>
         /// 嗅探到的地址可能来自不同 iframe，列表要加锁并限制长度，
         /// 只留最近若干个，供“当前播放地址取不到时”兜底用。
@@ -434,6 +466,300 @@ namespace WinFormsApp3
             await DownloadCurrentVideoAsync();
         }
 
+        private async void listBut_Click(object sender, EventArgs e)
+        {
+            await ShowVideoListAsync();
+        }
+
+        /// <summary>
+        /// 打开“本页视频列表”：列出全部候选并生成截图预览（每个视频 3 张、间隔 5 秒），
+        /// 用户对比确认哪个是当前视频后勾选，选文件夹批量下载。
+        /// </summary>
+        private async Task ShowVideoListAsync()
+        {
+            if (webView21.CoreWebView2 == null)
+            {
+                SetStatus("页面还没加载好，请稍候");
+                return;
+            }
+
+            if (downloadCts != null)
+            {
+                SetStatus("已有下载在进行中，可先点“取消下载”");
+                return;
+            }
+
+            listBut.Enabled = false;
+            try
+            {
+                SetStatus("正在识别本页视频…");
+                string raw = await webView21.CoreWebView2.ExecuteScriptAsync(BuildGrabScript());
+                (List<VideoCandidate> items, HashSet<string> currentUrls) = CollectCandidates(raw);
+
+                if (items.Count == 0)
+                {
+                    SetStatus("没识别到视频地址");
+                    MessageBox.Show(this,
+                        "本页没有识别到可下载的视频地址。\n\n" +
+                        "常见原因：\r\n1. 视频还没真正开始播放，请先点播放再点本按钮；\r\n"
+                        + "2. 站点用了加密流（DRM），无法直接下载；\r\n"
+                        + "3. 视频在 iframe 里且尚未加载完，稍等一两秒重试。",
+                        "下载列表", MessageBoxButtons.OK, MessageBoxIcon.Information);
+                    return;
+                }
+
+                // 关键：列表窗口是模态对话框，实测对话框存在期间 WebView2 的异步回调
+                // （ExecuteScriptAsync / GetCookiesAsync）不会送达，要等窗口关闭才一次性返回。
+                // 所以所有依赖 WebView2 的数据必须在 ShowDialog 之前预取完毕，
+                // 后台预览任务只做 ffmpeg 抽帧，不再碰 WebView2。
+                SetStatus("正在取登录态与播放器画面…");
+                Dictionary<string, string?> cookies = new Dictionary<string, string?>();
+                foreach (VideoCandidate item in items)
+                {
+                    if (!cookies.ContainsKey(item.Url))
+                    {
+                        cookies[item.Url] = await GetCookieHeaderAsync(item.Url);
+                    }
+                }
+                List<byte[]> canvasFrames = await CaptureCurrentFramesAsync(CancellationToken.None);
+                Image? currentStrip = VideoListForm.ComposeFrames(canvasFrames);
+                PreviewLog.Write($"预取完成 cookies={cookies.Count} canvas帧={canvasFrames.Count} strip={(currentStrip != null ? "ok" : "null")}");
+
+                SetStatus($"识别到 {items.Count} 个视频，正在生成截图…");
+                Func<VideoCandidate, CancellationToken, Task<(Image? Image, string? Error)>> factory =
+                    (c, ct) => BuildPreviewAsync(c, currentUrls.Contains(c.Url), currentStrip, cookies, ct);
+                using VideoListForm form = new VideoListForm(items, currentUrls, factory);
+                if (form.ShowDialog(this) != DialogResult.OK || form.SelectedCandidates.Count == 0)
+                {
+                    SetStatus("已取消");
+                    return;
+                }
+
+                using FolderBrowserDialog folderDlg = new FolderBrowserDialog
+                {
+                    Description = $"选择保存文件夹（将下载 {form.SelectedCandidates.Count} 个视频）"
+                };
+                if (folderDlg.ShowDialog(this) != DialogResult.OK)
+                {
+                    SetStatus("已取消");
+                    return;
+                }
+
+                await DownloadCandidatesBatchAsync(form.SelectedCandidates, folderDlg.SelectedPath);
+            }
+            catch (OperationCanceledException)
+            {
+                SetStatus("已取消");
+            }
+            catch (Exception ex)
+            {
+                SetStatus($"识别失败：{ex.Message}");
+                MessageBox.Show(this, ex.Message, "下载列表", MessageBoxButtons.OK, MessageBoxIcon.Warning);
+            }
+            finally
+            {
+                listBut.Enabled = true;
+            }
+        }
+
+        /// <summary>
+        /// 给列表行生成截图预览。当前正在播的视频直接用开窗前从播放器画面预取好的截图条
+        /// （不受防盗链和地址过期影响）；其余候选用 ffmpeg 带预取的 Referer/Cookie 读远端地址抽帧。
+        /// 这个方法在后台线程上跑，绝不能调 WebView2 API（模态对话框期间回调不会送达）。
+        /// </summary>
+        private async Task<(Image? Image, string? Error)> BuildPreviewAsync(
+            VideoCandidate candidate, bool isCurrent, Image? currentStrip,
+            IReadOnlyDictionary<string, string?> cookies, CancellationToken ct)
+        {
+            string shortUrl = candidate.Url.Length > 70 ? candidate.Url[..70] : candidate.Url;
+            PreviewLog.Write($"预览开始 isCurrent={isCurrent} url={shortUrl}");
+
+            // 只在内存里的播放列表文本没有可 seek 的地址，不抽帧
+            if (candidate.PlaylistText != null)
+            {
+                return (null, "内存播放列表，无法抽帧预览");
+            }
+
+            if (isCurrent && currentStrip != null)
+            {
+                PreviewLog.Write("预览成功：播放器画面预取帧");
+                return (currentStrip, null);
+            }
+
+            try
+            {
+                string? referer = candidate.Referer ?? RefererFor(candidate.Url, null);
+                cookies.TryGetValue(candidate.Url, out string? cookie);
+                VideoDownloader downloader = new VideoDownloader(referer, cookie);
+                PreviewLog.Write("ffmpeg 抽帧开始");
+                VideoDownloader.FrameExtraction result = await downloader.ExtractFramesAsync(candidate.Url, ct);
+                Image? img = VideoListForm.ComposeFrames(result.Frames);
+                PreviewLog.Write($"ffmpeg 抽帧结束 frames={result.Frames.Count} error={result.Error ?? "-"}");
+                return img != null ? (img, null) : (null, result.Error ?? "没抽到帧");
+            }
+            catch (OperationCanceledException)
+            {
+                PreviewLog.Write("预览被取消");
+                throw;
+            }
+            catch (Exception ex)
+            {
+                PreviewLog.Write($"预览异常 {ex.GetType().Name}: {ex.Message}");
+                return (null, ex.Message);
+            }
+        }
+
+        /// <summary>
+        /// 从正在播放的 <video> 元素里截 3 帧（2/7/12 秒，对应“每 5 秒 3 张”）：
+        /// 临时暂停→逐帧 seek+canvas 绘制→恢复原进度与播放状态；单次 seek 限 3 秒，
+        /// 遇到 tainted canvas（跨域污染）等异常就放弃，退回 ffmpeg 远程抽帧。
+        /// </summary>
+        private async Task<List<byte[]>> CaptureCurrentFramesAsync(CancellationToken ct)
+        {
+            List<byte[]> frames = new List<byte[]>();
+            try
+            {
+                if (webView21.CoreWebView2 == null) return frames;
+
+                // 后台线程不能直接碰 ExecuteScriptAsync，封送回 UI 线程；
+                // 整条脚本再加 20 秒硬超时，页面播放器抽风时不能把预览任务永久挂住
+                using var overall = CancellationTokenSource.CreateLinkedTokenSource(ct);
+                overall.CancelAfter(TimeSpan.FromSeconds(20));
+                string raw;
+                try
+                {
+                    raw = await OnUiAsync(() => webView21.CoreWebView2!.ExecuteScriptAsync(CurrentFramesScript))
+                        .WaitAsync(overall.Token);
+                }
+                catch (Exception ex) when (ex is OperationCanceledException or TimeoutException)
+                {
+                    PreviewLog.Write($"播放器取帧脚本超时/取消：{ex.GetType().Name}");
+                    return frames;
+                }
+                ct.ThrowIfCancellationRequested();
+                PreviewLog.Write($"播放器取帧脚本返回 {raw.Length} 字符");
+                string? inner = JsonSerializer.Deserialize<string>(raw);
+                if (string.IsNullOrEmpty(inner)) return frames;
+
+                if (JsonNode.Parse(inner)?["frames"] is JsonArray arr)
+                {
+                    foreach (JsonNode? item in arr)
+                    {
+                        string? dataUrl = item?.GetValue<string>();
+                        int comma = dataUrl?.IndexOf(',') ?? -1;
+                        if (dataUrl == null || comma < 0) continue;
+                        try { frames.Add(Convert.FromBase64String(dataUrl[(comma + 1)..])); }
+                        catch { /* 坏帧跳过 */ }
+                    }
+                }
+            }
+            catch (OperationCanceledException)
+            {
+                throw;
+            }
+            catch
+            {
+                // 播放器截图失败就退回 ffmpeg 远程抽帧
+            }
+            return frames;
+        }
+
+        private const string CurrentFramesScript = @"
+(async function(){
+  function findVideo(){
+    var vids=Array.prototype.slice.call(document.querySelectorAll('video'));
+    for(var i=0;i<vids.length;i++){ if(!vids[i].paused && vids[i].currentTime>0) return vids[i]; }
+    for(var j=0;j<vids.length;j++){ if(vids[j].videoWidth>0) return vids[j]; }
+    return vids[0]||null;
+  }
+  var v=findVideo();
+  if(!v) return JSON.stringify({frames:[]});
+  var times=[2,7,12], frames=[], wasPaused=v.paused, t0=v.currentTime;
+  try{
+    v.pause();
+    for(var k=0;k<times.length;k++){
+      var t=times[k];
+      if(isFinite(v.duration) && t>v.duration-0.2) t=v.duration>1?v.duration-0.5:0;
+      var ok=true;
+      try{
+        await new Promise(function(res,rej){
+          var done=false;
+          var to=setTimeout(function(){ if(!done){done=true;rej('t');} },3000);
+          v.onseeked=function(){ if(!done){done=true;clearTimeout(to);res();} };
+          try{ v.currentTime=t; }catch(e){ if(!done){done=true;clearTimeout(to);rej('s');} }
+        });
+      }catch(e){ ok=false; }
+      if(!ok) break;
+      try{
+        var c=document.createElement('canvas');
+        var w=v.videoWidth||480, h=v.videoHeight||270;
+        var sc=Math.min(1,480/w);
+        c.width=Math.round(w*sc); c.height=Math.round(h*sc);
+        c.getContext('2d').drawImage(v,0,0,c.width,c.height);
+        frames.push(c.toDataURL('image/jpeg',0.85));
+      }catch(e){ frames=[]; break; }
+    }
+  } finally {
+    // 注意：这里绝不能 await v.play()——抖音播放器会干预 play 的 Promise，
+    // 一旦 pending 不结束整段脚本永不返回，截图任务会永久挂死
+    try{
+      v.currentTime=t0;
+      if(!wasPaused){ try{ v.play().catch(function(){}); }catch(e){} }
+    }catch(e){}
+  }
+  return JSON.stringify({frames:frames});
+})()";
+
+        /// <summary>
+        /// 批量下载：逐个存进所选文件夹，音视频分离的轨对仍走精确合并；
+        /// 某条失败时询问是否继续，用户点取消则中止剩余条目。
+        /// </summary>
+        private async Task DownloadCandidatesBatchAsync(List<VideoCandidate> items, string folder)
+        {
+            int succeeded = 0;
+            List<string> failures = new List<string>();
+            VideoDownloader namer = new VideoDownloader(RefererFor(items[0].Url, webView21.CoreWebView2?.Source));
+
+            for (int i = 0; i < items.Count; i++)
+            {
+                VideoCandidate item = items[i];
+                string fileName = namer.SuggestedFileName(item.Url, PageTitle);
+                string filePath = UniqueFilePath(folder, fileName);
+
+                SetStatus($"批量下载 {i + 1}/{items.Count}：{fileName}");
+                downloadWasCanceled = false;
+                string? failure = await TryDownloadAsync(item, filePath, promptOpenFolder: false);
+
+                if (downloadWasCanceled) break; // 用户取消整个批次
+
+                if (failure == null)
+                {
+                    succeeded++;
+                }
+                else
+                {
+                    failures.Add($"{fileName}：{failure}");
+                    if (i < items.Count - 1 && MessageBox.Show(this,
+                            $"第 {i + 1} 个下载失败：\n{failure}\n\n跳过它继续下载剩下的吗？",
+                            "批量下载", MessageBoxButtons.YesNo, MessageBoxIcon.Question) != DialogResult.Yes)
+                    {
+                        break;
+                    }
+                }
+            }
+
+            string summary = $"成功 {succeeded} 个，失败 {failures.Count} 个（共 {items.Count}）。";
+            SetStatus($"批量下载完成：{summary}");
+            if (failures.Count > 0)
+            {
+                summary += "\n\n" + string.Join("\n", failures.Take(8)) + (failures.Count > 8 ? "\n…" : string.Empty);
+            }
+            MessageBox.Show(this, summary, "批量下载", MessageBoxButtons.OK,
+                failures.Count == 0 ? MessageBoxIcon.Information : MessageBoxIcon.Warning);
+
+            if (succeeded > 0) OpenFolder(folder);
+        }
+
         /// <summary>
         /// 只下载当前正在播放的那一个视频地址，不再列出一堆候选让用户挑。
         /// </summary>
@@ -512,40 +838,13 @@ namespace WinFormsApp3
         /// </summary>
         private VideoCandidate? CollectCurrentCandidate(string grabResultJson)
         {
-            string current = string.Empty;
-            string pageUrl = string.Empty;
-            string dashVideo = string.Empty;
-            string dashAudio = string.Empty;
-            string videoId = string.Empty;
-            List<string> sniffed = new List<string>();
-
-            try
-            {
-                // ExecuteScriptAsync 返回的是 JSON 编码后的字符串，需要先脱一层引号
-                string? inner = JsonSerializer.Deserialize<string>(grabResultJson);
-                if (!string.IsNullOrEmpty(inner))
-                {
-                    JsonNode? node = JsonNode.Parse(inner);
-                    current = node?["current"]?.GetValue<string>() ?? string.Empty;
-                    pageUrl = node?["pageUrl"]?.GetValue<string>() ?? string.Empty;
-                    dashVideo = node?["dashVideo"]?.GetValue<string>() ?? string.Empty;
-                    dashAudio = node?["dashAudio"]?.GetValue<string>() ?? string.Empty;
-                    videoId = node?["videoId"]?.GetValue<string>() ?? string.Empty;
-
-                    if (node?["sniffed"] is JsonArray arr)
-                    {
-                        foreach (JsonNode? item in arr)
-                        {
-                            string? u = item?.GetValue<string>();
-                            if (!string.IsNullOrEmpty(u)) sniffed.Add(u);
-                        }
-                    }
-                }
-            }
-            catch
-            {
-                // 页面没有返回可解析结果时，只用宿主侧嗅探到的地址
-            }
+            GrabInfo g = ParseGrab(grabResultJson);
+            string pageUrl = g.PageUrl;
+            List<string> sniffed = g.Sniffed;
+            string dashVideo = g.DashVideo;
+            string dashAudio = g.DashAudio;
+            string videoId = g.VideoId;
+            string current = g.Current;
 
             // 第一层：video 标签自己的播放源
             if (VideoDownloader.LooksLikeMedia(current) && !VideoDownloader.IsSegmentUrl(current))
@@ -594,6 +893,125 @@ namespace WinFormsApp3
             return text == null ? null : new VideoCandidate(pageUrl, text, pageUrl);
         }
 
+        /// <summary>
+        /// 抓取脚本回包的解析结果，当前下载与列表两条路径共用。
+        /// </summary>
+        private sealed class GrabInfo
+        {
+            public string Current = string.Empty;
+            public string PageUrl = string.Empty;
+            public string DashVideo = string.Empty;
+            public string DashAudio = string.Empty;
+            public string VideoId = string.Empty;
+            public List<string> Sniffed = new();
+        }
+
+        private static GrabInfo ParseGrab(string grabResultJson)
+        {
+            GrabInfo g = new GrabInfo();
+            try
+            {
+                // ExecuteScriptAsync 返回的是 JSON 编码后的字符串，需要先脱一层引号
+                string? inner = JsonSerializer.Deserialize<string>(grabResultJson);
+                if (!string.IsNullOrEmpty(inner))
+                {
+                    JsonNode? node = JsonNode.Parse(inner);
+                    g.Current = node?["current"]?.GetValue<string>() ?? string.Empty;
+                    g.PageUrl = node?["pageUrl"]?.GetValue<string>() ?? string.Empty;
+                    g.DashVideo = node?["dashVideo"]?.GetValue<string>() ?? string.Empty;
+                    g.DashAudio = node?["dashAudio"]?.GetValue<string>() ?? string.Empty;
+                    g.VideoId = node?["videoId"]?.GetValue<string>() ?? string.Empty;
+
+                    if (node?["sniffed"] is JsonArray arr)
+                    {
+                        foreach (JsonNode? item in arr)
+                        {
+                            string? u = item?.GetValue<string>();
+                            if (!string.IsNullOrEmpty(u)) g.Sniffed.Add(u!);
+                        }
+                    }
+                }
+            }
+            catch
+            {
+                // 页面没有返回可解析结果时，只用宿主侧嗅探到的地址
+            }
+            return g;
+        }
+
+        /// <summary>
+        /// 给“列表”按钮收集本页全部候选：当前播放源、DASH 视频轨排最前并标记为当前，
+        /// 其余嗅探到的整片地址按新旧倒序追加；每条都尝试配对同组音频轨，下载时精确合并。
+        /// </summary>
+        private (List<VideoCandidate> Items, HashSet<string> CurrentUrls) CollectCandidates(string grabResultJson)
+        {
+            GrabInfo g = ParseGrab(grabResultJson);
+            List<VideoCandidate> items = new List<VideoCandidate>();
+            HashSet<string> currentUrls = new HashSet<string>();
+
+            void Add(string? url, string? audio, bool isCurrent)
+            {
+                if (string.IsNullOrEmpty(url)
+                    || !VideoDownloader.LooksLikeMedia(url)
+                    || VideoDownloader.IsSegmentUrl(url)
+                    || VideoDownloader.IsDashAudioOnly(url))
+                {
+                    return;
+                }
+                if (items.Any(i => i.Url == url))
+                {
+                    if (isCurrent) currentUrls.Add(url!);
+                    return;
+                }
+
+                // 只有 DASH 纯视频轨才需要配音频轨；普通整片直链自带音轨，乱配反而会把别人的声音合进去
+                string? pairedAudio = audio ?? (VideoDownloader.IsDashVideoOnly(url)
+                    ? FindPairedAudio(url!, isCurrent ? g.VideoId : IdFromUrl(url!))
+                    : null);
+                items.Add(new VideoCandidate(url, null, RefererFor(url, g.PageUrl), pairedAudio));
+                if (isCurrent) currentUrls.Add(url!);
+            }
+
+            // 当前播放的两条源排最前，方便和下面的嗅探条目肉眼对比
+            Add(g.Current, null, true);
+            Add(g.DashVideo, string.IsNullOrEmpty(g.DashAudio) ? null : g.DashAudio, true);
+
+            List<string> pool = g.Sniffed.Concat(SnapshotSniffedUrls())
+                .Distinct()
+                .ToList();
+
+            // 有视频 ID 时先把同 ID 的地址排前面，它们多半就是当前视频
+            if (!string.IsNullOrEmpty(g.VideoId))
+            {
+                pool = pool.OrderByDescending(u => u.Contains(g.VideoId)).ToList();
+            }
+
+            // 嗅探列表里越新的越接近当前视频，倒序追加
+            for (int i = pool.Count - 1; i >= 0; i--)
+            {
+                string url = pool[i];
+                Add(url, null, !string.IsNullOrEmpty(g.VideoId) && url.Contains(g.VideoId));
+            }
+
+            return (items, currentUrls);
+        }
+
+        /// <summary>
+        /// 从地址里提视频 ID（抖音这类地址路径里带 10 位以上纯数字），用于音频轨配对。
+        /// </summary>
+        private static string IdFromUrl(string url)
+        {
+            try
+            {
+                Match m = Regex.Match(new Uri(url).AbsolutePath, @"\d{10,}");
+                return m.Success ? m.Value : string.Empty;
+            }
+            catch
+            {
+                return string.Empty;
+            }
+        }
+
         /// <summary>
         /// 从已嗅探地址里找和视频轨同组的 DASH 音频轨。
         /// 有 videoId 时优先选 URL 里包含该 ID 的音频轨，否则取最后一条 media-audio。
@@ -676,8 +1094,9 @@ namespace WinFormsApp3
 
         /// <summary>
         /// 执行一次下载。返回 null 表示成功或用户主动取消，否则返回错误信息给上层提示。
+        /// 批量下载时 promptOpenFolder 传 false，避免每条都弹“打开文件夹”。
         /// </summary>
-        private async Task<string?> TryDownloadAsync(VideoCandidate candidate, string filePath)
+        private async Task<string?> TryDownloadAsync(VideoCandidate candidate, string filePath, bool promptOpenFolder = true)
         {
             VideoDownloader downloader = await CreateDownloaderAsync(candidate);
 
@@ -706,7 +1125,7 @@ namespace WinFormsApp3
 
                 SetStatus($"已下载 {Path.GetFileName(result.FilePath)}（{VideoDownloader.FormatSize(result.Bytes)}）");
 
-                if (MessageBox.Show(this, $"视频已保存到：\n{result.FilePath}\n\n要打开所在文件夹吗？",
+                if (promptOpenFolder && MessageBox.Show(this, $"视频已保存到：\n{result.FilePath}\n\n要打开所在文件夹吗？",
                         "下载完成", MessageBoxButtons.YesNo, MessageBoxIcon.Information) == DialogResult.Yes)
                 {
                     OpenFolder(result.FilePath);
@@ -716,7 +1135,8 @@ namespace WinFormsApp3
             }
             catch (OperationCanceledException)
             {
-                // 用户主动取消就别再换地址重试了
+                // 用户主动取消就别再换地址重试了；批量路径靠这个标志中止剩余条目
+                downloadWasCanceled = true;
                 SetStatus("已取消下载");
                 return null;
             }
@@ -745,7 +1165,11 @@ namespace WinFormsApp3
             return new VideoDownloader(referer, cookie);
         }
 
-        private async Task<string?> GetCookieHeaderAsync(string url)
+        /// <summary>
+        /// 取 Cookie 也是 CoreWebView2 COM 调用，同样封送回 UI 线程，
+        /// 否则截图预览的后台任务会在这里永久卡死。
+        /// </summary>
+        private Task<string?> GetCookieHeaderAsync(string url) => OnUiAsync(async () =>
         {
             CoreWebView2? core = webView21.CoreWebView2;
             if (core == null || !Uri.TryCreate(url, UriKind.Absolute, out Uri? uri)) return null;
@@ -763,7 +1187,7 @@ namespace WinFormsApp3
                 // 拿不到 Cookie 就按匿名请求下载
                 return null;
             }
-        }
+        });
 
         private void ReportProgress(DownloadProgress value)
         {
@@ -801,6 +1225,23 @@ namespace WinFormsApp3
             }
         }
 
+        /// <summary>
+        /// 批量下载时同页多个候选可能推断出同名文件，重名时加序号避免互相覆盖。
+        /// </summary>
+        private static string UniqueFilePath(string folder, string fileName)
+        {
+            string path = Path.Combine(folder, fileName);
+            if (!File.Exists(path)) return path;
+
+            string name = Path.GetFileNameWithoutExtension(fileName);
+            string ext = Path.GetExtension(fileName);
+            for (int i = 2; ; i++)
+            {
+                path = Path.Combine(folder, $"{name} ({i}){ext}");
+                if (!File.Exists(path)) return path;
+            }
+        }
+
         private static void OpenFolder(string filePath)
         {
             try