Dropbox 文件夹下载问题 (c#)

Question

我正在通过网络链接自动从我的 Dropbox - storage(?) 下载整个文件夹，例如：https://www.dropbox.com/sh/bunchOfLetters/somthnsomthn?dl=1，只有一个基本的网络客户端：

using (WebClient wc = new WebClient())
{
     wc.DownloadFile(new Uri(uri), _basePath + localPath);
}

文件夹自然以 .rar 文件形式出现（由于 Dropbox 的下载系统），如果我尝试手动打开文件（通过 Winrar），则完全没有问题。现在问题来了....如果我尝试使用任何类型的自动库（如 unrar 或 SharpCompress），它总是给我一个 'Corupted Header' 就好像下载不会得到所有东西或文件刚刚坏了..但是仍然用 Winrar 打开它工作得很好。

如果有人知道如何以及为什么；我很高兴听到你的想法。

编辑：

这是我用于 SharpCompress 的函数：

public static bool ExtractToFolder(string extractionPackage, string outputPath)
        {
            if (extractionPackage == null) throw new ArgumentNullException(nameof(extractionPackage));
            if (outputPath == null) throw new ArgumentNullException(nameof(outputPath));
            if (string.IsNullOrEmpty(extractionPackage))
                throw new ArgumentException("Argument is null or empty", nameof(extractionPackage));
            if (string.IsNullOrEmpty(outputPath))
                throw new ArgumentException("Argument is null or empty", nameof(outputPath));
            if (!extractionPackage.EndsWith(".rar")) throw new InvalidDataException("not a .rar File");
            Directory.CreateDirectory(outputPath);

            try
            {
                using (Stream stream = File.OpenRead(extractionPackage))
                using (RarReader reader = RarReader.Open(stream))
                {
                    while (reader.MoveToNextEntry())
                    {
                        reader.WriteEntryToDirectory(outputPath, ExtractOptions.ExtractFullPath | ExtractOptions.Overwrite);
                    }
                }

                return true;
            }
            catch
            {
                return false;
            }
        }

如果有人对 unrar 感兴趣： ..我知道它做得不好，但它仍然适用于普通文件...只是不适用于 Dropbox 文件

namespace Cryptus.Rar
{
/// <summary>
/// just for compatibility purposes, use <see cref="SharpCompress"/>
/// </summary>
public class Unrar
{
    public enum RarOperations
    {
        OP_EXTRACT = 0,
        OP_TEST = 1,
        OP_LIST = 2
    }

    public const int ERAR_END_ARCHIVE = 10;
    public const int ERAR_NO_MEMORY = 11;
    public const int ERAR_BAD_DATA = 12;
    public const int ERAR_BAD_ARCHIVE = 13;
    public const int ERAR_UNKNOWN_FORMAT = 14;
    public const int ERAR_EOPEN = 15;
    public const int ERAR_ECREATE = 16;
    public const int ERAR_ECLOSE = 17;
    public const int ERAR_EREAD = 18;
    public const int ERAR_EWRITE = 19;
    public const int ERAR_SMALL_BUF = 20;

    public const int RAR_OM_LIST = 0;
    public const int RAR_OM_EXTRACT = 1;

    public const int RAR_SKIP = 0;
    public const int RAR_TEST = 1;
    public const int RAR_EXTRACT = 2;

    public const int RAR_VOL_ASK = 0;
    public const int RAR_VOL_NOTIFY = 1;

    [DllImport("unrar.dll")]
    public static extern IntPtr RAROpenArchive(ref RAROpenArchiveData ArchiveData);

    [DllImport("unrar.dll")]
    public static extern int RARCloseArchive(IntPtr hArcData);

    [DllImport("unrar.dll")]
    public static extern int RARReadHeader(IntPtr hArcData, ref RARHeaderData HeaderData);

    [DllImport("unrar.dll")]
    public static extern IntPtr RAROpenArchiveEx(ref RAROpenArchiveDataEx ArchiveData);

    [DllImport("unrar.dll")]
    public static extern int RARReadHeaderEx(IntPtr hArcData, ref RARHeaderDataEx HeaderData);

    [DllImport("unrar.dll")]
    public static extern int RARProcessFile(IntPtr hArcData, int Operation, string DestPath, string DestName);

    [DllImport("unrar.dll")]
    public static extern int RARGetDllVersion();

    [DllImport("user32.dll")]
    private static extern bool CharToOem(string lpszSrc, [Out] StringBuilder lpszDst);

    /// <summary>
    ///     opens an arcive and unloads its content to destDolder
    /// </summary>
    /// <param name="strFileName">input .rar File</param>
    /// <param name="destFolder">destination Folder</param>
    public void UnloadArchieve(string strFileName, string destFolder)
    {
        IntPtr lHandle;
        int iStatus;
        RAROpenArchiveData uRAR = new RAROpenArchiveData();
        RARHeaderData uHeader = new RARHeaderData();

        uRAR.ArcName = strFileName + char.MinValue;
        uRAR.OpenMode = RAR_OM_EXTRACT;
        uRAR.CmtBuf = null;

        string ExtractDir = Path.GetDirectoryName(strFileName);
        StringBuilder sbDir = new StringBuilder();
        CharToOem(destFolder, sbDir);

        lHandle = RAROpenArchive(ref uRAR);
        if (uRAR.OpenResult != 0)
            Console.Write("Unable to open the Archieve!!!");
        while (RARReadHeader(lHandle, ref uHeader) == 0)
        {
            int result = RARProcessFile(lHandle, 2, sbDir.ToString(), null);
            if (0 != result)
                Console.Write("Unable to open the Archieve!!!");
        }


        iStatus = RARCloseArchive(lHandle);
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct RARHeaderData
    {
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
        public string ArcName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
        public string FileName;
        public uint Flags;
        public uint PackSize;
        public uint UnpSize;
        public uint HostOS;
        public uint FileCRC;
        public uint FileTime;
        public uint UnpVer;
        public uint Method;
        public uint FileAttr;
        public string CmtBuf;
        public uint CmtBufSize;
        public uint CmtSize;
        public uint CmtState;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct RAROpenArchiveData
    {
        public string ArcName;
        public uint OpenMode;
        public uint OpenResult;
        public string CmtBuf;
        public uint CmtBufSize;
        public uint CmtSize;
        public uint CmtState;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct RAROpenArchiveDataEx
    {
        public string ArcName;
        public string ArcNameW;
        public uint OpenMode;
        public uint OpenResult;
        public string CmtBuf;
        public uint CmtBufSize;
        public uint CmtSize;
        public uint CmtState;
        public uint Flags;
        public uint Reserved;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct RARHeaderDataEx
    {
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
        public string ArcName;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
        public string FileName;
        public string FileNameW;
        public uint Flags;
        public uint PackSize;
        public uint PackSizeHigh;
        public uint UnpSize;
        public uint UnpSizeHigh;
        public uint HostOS;
        public uint FileCRC;
        public uint FileTime;
        public uint UnpVer;
        public uint Method;
        public uint FileAttr;
        public string CmtBuf;
        public uint CmtBufSize;
        public uint CmtSize;
        public uint CmtState;
        public uint Reserved;
    }
}

Answer 1

好的，看来@smarx 的评论是对的！有点奇怪，但 Dropbox 生成的 .rar 文件不包含 rar，而是包含 zip header。这对于 header 格式的任何形式的自动检测都没有问题，但是如果你使用 rar 提取方法（应该用于 .rar 文件..）它不会工作。

Dropbox 文件夹下载问题 (c#)

Dropbox folder download issue (c#)

c#

webclient

dropbox

unrar

sharpcompress