refactor(downloader): 重构下载器分片与系统资源分配逻辑

PCL.Core/App/Config.cs

@@ -72,8 +72,11 @@ public static partial class Config
     /// </summary>
     [ConfigGroup("Download")] partial class DownloadConfigGroup
     {
+        // 保留原配置键，升级后仍沿用用户已设置的数值（值 + 1 为连接上限）。
         [ConfigItem<int>("ToolDownloadThread", 63)] public partial int ThreadLimit { get; set; }
+        [ConfigItem<int>("ToolDownloadFileConnection", 7)] public partial int FileConnectionLimit { get; set; }
         [ConfigItem<int>("ToolDownloadSpeed", 42)] public partial int SpeedLimit { get; set; }
+        [ConfigItem<DownloadHttpMode>("ToolDownloadHttpMode", DownloadHttpMode.Auto)] public partial DownloadHttpMode HttpMode { get; set; }
         [ConfigItem<int>("ToolDownloadSource", 1)] public partial int FileSource { get; set; }
         [ConfigItem<int>("ToolDownloadVersion", 1)] public partial int VersionListSource { get; set; }
         [ConfigItem<bool>("ToolDownloadAutoSelectVersion", true)] public partial bool AutoSelectInstance { get; set; }

PCL.Core/App/ConfigEnums.cs

@@ -9,6 +9,16 @@ public enum LinkProtocolPreference
     Udp
 }
 
+/// <summary>
+/// 文件下载使用的 HTTP 协议模式。
+/// </summary>
+public enum DownloadHttpMode
+{
+    Auto = 0,
+    Http11 = 1,
+    Http2 = 2
+}
+
 /// <summary>
 /// 主题模式（亮/暗/系统）
 /// </summary>

PCL.Core/App/Localization/Languages/en-US.xaml

@@ -2672,10 +2672,19 @@
     <sys:String x:Key="Setup.GameManage.Download.SpeedLimit.ToolTip">Set a download speed cap to prevent other programs that depend on the internet from freezing during downloads.</sys:String>
     <sys:String x:Key="Setup.GameManage.Download.TargetFolder">Target folder</sys:String>
     <sys:String x:Key="Setup.GameManage.Download.TargetFolder.Hint">Go to Launch → Selection → Folder list to change the download target folder.&#xA;Right-click a folder or game instance to open the corresponding folder.</sys:String>
-    <sys:String x:Key="Setup.GameManage.Download.Threads">Max threads</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.Threads">Max concurrent connections</sys:String>
     <sys:String x:Key="Setup.GameManage.Download.Threads.TooManyWarning.Confirm">I see</sys:String>
-    <sys:String x:Key="Setup.GameManage.Download.Threads.TooManyWarning.Message">Setting too many download threads may cause serious lag during downloads.&#xA;64 threads are generally enough for most download needs. Unless you know what you are doing, it is not recommended to set a higher value!</sys:String>
-    <sys:String x:Key="Setup.GameManage.Download.Threads.ToolTip">More threads can speed up rate-limited downloads, but too many may cause serious lag during downloads.&#xA;In general, 64 threads are enough for most download needs.</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.Threads.TooManyWarning.Message">A high connection limit can lead to severe lag or even stricter throttling strategies from the server.&#xA;64 connections are usually sufficient. Do not set it higher unless you know what you are doing!</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.Threads.ToolTip">Limits the total network connections used by all download tasks. 64 connections are usually sufficient.</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.FileConnections">Max connections per file</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.FileConnections.ToolTip">The most connections a large file may use at once. A higher value can help sources that cap each connection, but may also trigger source throttling.</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol">File download protocol</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Auto">Automatic (recommended)</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Auto.ToolTip">Prefer HTTP/2 for small files and batch downloads, and use HTTP/1.1 for large segmented downloads to balance concurrency and compatibility.</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Http11">HTTP/1.1</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Http11.ToolTip">Force HTTP/1.1 for all file downloads. This can help environments where independent connections improve large-file throughput.</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Http2">Prefer HTTP/2</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Http2.ToolTip">Prefer HTTP/2 for all file downloads, falling back to HTTP/1.1 when the source or proxy does not support it.</sys:String>
     <sys:String x:Key="Setup.GameManage.Download.Unlimited">Unlimited</sys:String>
 
     <!-- Setup.Java -->
@@ -3226,7 +3235,7 @@
     <sys:String x:Key="Speed.Error.Copied">Error details copied!</sys:String>
     <sys:String x:Key="Speed.Error.OperationFailed">A task manager operation failed. See the details below.</sys:String>
     <sys:String x:Key="Speed.Progress.RemainingFiles">Remaining files</sys:String>
-    <sys:String x:Key="Speed.Progress.RemainingThreads">Remaining threads</sys:String>
+    <sys:String x:Key="Speed.Progress.RemainingThreads">Active connections</sys:String>
     <sys:String x:Key="Speed.Progress.Speed">Download speed</sys:String>
     <sys:String x:Key="Speed.Progress.Total">Total progress</sys:String>
 
@@ -3570,4 +3579,4 @@
     <sys:String x:Key="Watcher.WindowLoaded">Minecraft window loaded: {0} ({1})</sys:String>
     <sys:String x:Key="Watcher.WindowMaximized">Minecraft window maximized: {0}</sys:String>
 
-</ResourceDictionary>
+</ResourceDictionary>

PCL.Core/App/Localization/Languages/zh-CN.xaml

@@ -2672,10 +2672,19 @@
     <sys:String x:Key="Setup.GameManage.Download.SpeedLimit.ToolTip">设置下载的速度上限，以避免在下载时导致其他需要联网的程序卡死</sys:String>
     <sys:String x:Key="Setup.GameManage.Download.TargetFolder">目标文件夹</sys:String>
     <sys:String x:Key="Setup.GameManage.Download.TargetFolder.Hint">请在 启动 → 实例选择 → 文件夹列表 中更改下载目标文件夹。&#xA;在某个文件夹或游戏实例上右键，即可选择打开对应文件夹。</sys:String>
-    <sys:String x:Key="Setup.GameManage.Download.Threads">最大线程数</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.Threads">最大并发连接数</sys:String>
     <sys:String x:Key="Setup.GameManage.Download.Threads.TooManyWarning.Confirm">我知道了</sys:String>
-    <sys:String x:Key="Setup.GameManage.Download.Threads.TooManyWarning.Message">如果设置过多的下载线程，可能会导致下载时出现非常严重的卡顿。&#xA;一般设置 64 线程即可满足大多数下载需求，除非你知道你在干什么，否则不建议设置更多的线程数！</sys:String>
-    <sys:String x:Key="Setup.GameManage.Download.Threads.ToolTip">线程数越多，限速的文件下载越快，但过高的线程数可能会造成下载时非常严重的卡顿。&#xA;一般而言，64 线程已可以保证足够的下载速度。</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.Threads.TooManyWarning.Message">过高的并发连接数可能导致下载时出现非常严重的卡顿，甚至导致服务器使用更严格的限速策略。&#xA;64 个连接通常已经可以满足需求。除非你知道自己在做什么，否则不建议设置更高的并发连接数！</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.Threads.ToolTip">限制所有下载任务合计使用的网络连接数。64 个连接通常已经足够。</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.FileConnections">单文件最大连接数</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.FileConnections.ToolTip">大文件最多同时使用的连接数。提高该值可能加快被单连接限速的下载，但也有可能更容易被下载源限速。</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol">文件下载协议</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Auto">自动选择（推荐）</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Auto.ToolTip">小文件和批量下载优先使用 HTTP/2；大文件分段下载使用 HTTP/1.1，以兼顾并发和兼容性。</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Http11">HTTP/1.1</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Http11.ToolTip">所有文件下载强制使用 HTTP/1.1。适合需要多条独立连接提升大文件速度的网络环境。</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Http2">优先使用 HTTP/2</sys:String>
+    <sys:String x:Key="Setup.GameManage.Download.HttpProtocol.Http2.ToolTip">所有文件下载优先使用 HTTP/2；如果下载源或代理不支持，会自动回退到 HTTP/1.1。</sys:String>
     <sys:String x:Key="Setup.GameManage.Download.Unlimited">无限制</sys:String>
 
     <!-- Setup.Java -->
@@ -3226,7 +3235,7 @@
     <sys:String x:Key="Speed.Error.Copied">已复制错误详情！</sys:String>
     <sys:String x:Key="Speed.Error.OperationFailed">任务管理操作失败。请查看错误详情。</sys:String>
     <sys:String x:Key="Speed.Progress.RemainingFiles">剩余文件</sys:String>
-    <sys:String x:Key="Speed.Progress.RemainingThreads">剩余线程</sys:String>
+    <sys:String x:Key="Speed.Progress.RemainingThreads">活动连接</sys:String>
     <sys:String x:Key="Speed.Progress.Speed">下载速度</sys:String>
     <sys:String x:Key="Speed.Progress.Total">总进度</sys:String>
 
@@ -3570,4 +3579,4 @@
     <sys:String x:Key="Watcher.WindowLoaded">Minecraft 窗口已加载：{0}（{1}）</sys:String>
     <sys:String x:Key="Watcher.WindowMaximized">已最大化 Minecraft 窗口：{0}</sys:String>
 
-</ResourceDictionary>
+</ResourceDictionary>

PCL.Core/IO/Net/NetworkService.cs

@@ -143,6 +143,7 @@ private static void _Stop()
         AllowAutoRedirect = true,
         MaxAutomaticRedirections = 20,
         UseCookies = false,
+        EnableMultipleHttp2Connections = true,
         ConnectCallback = Config.Network.EnableDoH ? HostConnectionHandler.Instance.GetConnectionAsync : null
     };
 

Plain Craft Launcher 2/Modules/Base/ModSetup.cs

@@ -31,6 +31,8 @@ public ModSetup()
         // === Tool ===
         Config.Download.ThreadLimitConfig.Observe(new ConfigObserver(ConfigEvent.Changed,
             e => ToolDownloadThread((int)e.Value!)));
+        Config.Download.FileConnectionLimitConfig.Observe(new ConfigObserver(ConfigEvent.Changed,
+            e => ToolDownloadFileConnection((int)e.Value!)));
         Config.Download.SpeedLimitConfig.Observe(new ConfigObserver(ConfigEvent.Changed,
             e => ToolDownloadSpeed((int)e.Value!)));
 
@@ -113,6 +115,7 @@ public static void ApplyAll()
 
         // Tool
         ToolDownloadThread(Config.Download.ThreadLimit);
+        ToolDownloadFileConnection(Config.Download.FileConnectionLimit);
         ToolDownloadSpeed(Config.Download.SpeedLimit);
 
         // UI - Launcher
@@ -195,7 +198,13 @@ public static void LaunchRamType(int type)
 
     public static void ToolDownloadThread(int value)
     {
-        ModNet.NetTaskThreadLimit = value + 1;
+        ModNet.NetTaskConnectionLimit = Math.Clamp(value + 1, 1, ModNet.NetTaskConnectionLimitMax);
+    }
+
+    public static void ToolDownloadFileConnection(int value)
+    {
+        ModNet.NetTaskSingleFileConnectionLimit = Math.Clamp(value + 1, 1,
+            ModNet.NetTaskSingleFileConnectionLimitMax);
     }
 
     public static void ToolDownloadSpeed(int value)

Plain Craft Launcher 2/Modules/Minecraft/ModDownload.cs

@@ -64,8 +64,10 @@ public static DownloadFile DlClientAssetIndexGet(McInstance version)
         var indexUrl = (string)(indexInfo["url"] ?? "");
         if (string.IsNullOrEmpty(indexUrl)) return null;
 
+        // 避免下载器先发一次 Range 探测请求，再回退到顺序下载
+        var indexSize = indexInfo["size"] is null ? -1L : (long)indexInfo["size"];
         return new DownloadFile(DlSourceLauncherOrMetaGet(indexUrl), indexAddress,
-            new ModBase.FileChecker(canUseExistsFile: false));
+            new ModBase.FileChecker(actualSize: indexSize, canUseExistsFile: false));
     }
 
     /// <summary>

Plain Craft Launcher 2/Modules/Minecraft/ModSkin.cs

@@ -153,9 +153,7 @@ public static string McSkinDownload(string address)
         {
             if (!File.Exists(fileAddress))
             {
-                FileDownloader.DownloadAsync(address, fileAddress + ModNet.netDownloadEnd).GetAwaiter().GetResult();
-                File.Delete(fileAddress);
-                FileSystem.Rename(fileAddress + ModNet.netDownloadEnd, fileAddress);
+                FileDownloader.DownloadAsync(address, fileAddress).GetAwaiter().GetResult();
                 ModBase.Log("[Minecraft] 皮肤下载成功：" + fileAddress);
             }