大家好这里是皇鱼
本文将接着上一篇文章的内容继续下载版本资源文件
本文以C#为例，那么开始。
特别感谢：bmclapi源让我的下载速度提升

解析资源文件

将资源索引文件中的objects这个json对象的每个value都访问一遍，里面会有

     {
          "hash": "b62ca8ec10d07e6bf5ac8dae0c8c1d2e6a1e3356", "size": 9101
     }

你需要提取其中的hash，这不仅是用于校验，还用于获取下载链接以及存储路径。
下载链接是

      https://resources.download.minecraft.net/hash的前两位/hash

以上述例子为例，下载链接就是

      https://resources.download.minecraft.net/b6/b62ca8ec10d07e6bf5ac8dae0c8c1d2e6a1e3356

存储路径就是

      .minecraft/assets/objects/hash的前两位/hash

这里就不写例子了
由于objects中有很多小文件，且都是在mojang服务器上存储，强烈建议搭配镜像源与多线程进行下载

http://resources.download.minecraft.net -> https://bmclapi2.bangbang93.com/assets

C#代码示例：

    async public static void downloadAssets()
    {
        Directory.CreateDirectory("./.minecraft/assets/indexes");
        Console.WriteLine("Downloading assetIndex...");
        string indexJson = File.ReadAllText(@".\.minecraft\versions\1.21\1.21.json");
        string assetIndextUrl = GetValueFromJson(indexJson, "assetIndex.url");
        string aiid = GetValueFromJson(indexJson, "assetIndex.id");
        using (WebClient client = new WebClient())
        {
            client.DownloadFile(assetIndextUrl.Replace("piston-meta.mojang.com", "bmclapi2.bangbang93.com"), $"./.minecraft/assets/indexes/{aiid}.json");
        }
        Console.WriteLine("Parsing assets...");
        string objects = GetValueFromJson(File.ReadAllText($"./.minecraft/assets/indexes/{aiid}.json"), "objects");
        Dictionary<string, string> assets = new Dictionary<string, string>();
        using (JsonDocument doc = JsonDocument.Parse(objects))
        {
            JsonElement root = doc.RootElement;
            if (root.ValueKind == JsonValueKind.Object)
            {
                foreach (JsonProperty property in root.EnumerateObject())
                {
                    string hash = GetValueFromJson(property.Value.ToString(), "hash");
                    string url = $"https://bmclapi2.bangbang93.com/assets/{hash.Substring(0, 2)}/{hash}";
                    string path = $"./.minecraft/assets/objects/{hash.Substring(0, 2)}/{hash}";
                    assets.TryAdd(url, path);
                }
            }
        }
        Console.WriteLine("Downloading assets");
        await DownloadFilesAsync(assets);



    }
    static async Task DownloadFilesAsync(Dictionary<string, string> files)
    {
        using (HttpClient client = new HttpClient())
        {
            List<Task> downloadTasks = new List<Task>();

            foreach (var file in files)
            {
                string url = file.Key;
                string filePath = file.Value;
                Directory.CreateDirectory(Path.GetDirectoryName(filePath));
                downloadTasks.Add(DownloadFileAsync(client, url, filePath));
            }

            await Task.WhenAll(downloadTasks);
        }
    }

    static async Task DownloadFileAsync(HttpClient client, string url, string filePath)
    {
        int i = 0;
        while (true)
        {
            if(i >= 50){
                Console.WriteLine($"download failed:{url}");
                break;
            }
            try
            {
                HttpResponseMessage response = await client.GetAsync(url);
                response.EnsureSuccessStatusCode();

                byte[] fileBytes = await response.Content.ReadAsByteArrayAsync();
                await File.WriteAllBytesAsync(filePath, fileBytes);

                Console.WriteLine($"Downloaded {url} to {filePath}");
                break;
            }
            catch
            {
                i++
                continue;
            }
        }
    }

运行截图：


查看路径

资源文件下载完成
下次讲启动游戏

参考资料

Minecraft Wiki - https://zh.minecraft.wiki
BMCLAPI - https://bmclapidoc.bangbang93.com
HMCL源代码 - https://github.com/HMCL-dev/HMCL/
PCL2源代码 - https://github.com/Hex-Dragon/PCL2