用C#实现一个zip解压功能，无需引入dll（可直接放到Unity中使用）

一、前言

最近在搞C#的winform窗体应用实现一个微型下载器功能。过程中需要解压文件，又不想引入一个dll，从GitHub上找到了一个UnZip库源码，实测可用。

二、使用

解压

using (var unzip = new Unzip("./test.zip"))
{
    unzip.ExtractToDirectory("./test");
}

三、Unzip源码

// Unzip class for .NET 3.5 Client Profile or Mono 2.10
// Written by Alexey Yakovlev <yallie@yandex.ru>
// https://github.com/yallie/unzip

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.IO.Compression;
using System.Linq;
using System.Text;

namespace Internals
{
  /// <summary>
  /// Unzip helper class.
  /// </summary>
  internal class Unzip : IDisposable
  {
    /// <summary>
    /// Zip archive entry.
    /// </summary>
    public class Entry
    {
      /// <summary>
      /// Gets or sets the name of a file or a directory.
      /// </summary>
      public string Name { get; set; }

      /// <summary>
      /// Gets or sets the comment.
      /// </summary>
      public string Comment { get; set; }

      /// <summary>
      /// Gets or sets the CRC32.
      /// </summary>
      public uint Crc32 { get; set; }

      /// <summary>
      /// Gets or sets the compressed size of the file.
      /// </summary>
      public int CompressedSize { get; set; }

      /// <summary>
      /// Gets or sets the original size of the file.
      /// </summary>
      public int OriginalSize { get; set; }

      /// <summary>
      /// Gets or sets a value indicating whether this <see cref="Entry" /> is deflated.
      /// </summary>
      public bool Deflated { get; set; }

      /// <summary>
      /// Gets a value indicating whether this <see cref="Entry" /> is a directory.
      /// </summary>
      public bool IsDirectory { get { return Name.EndsWith("/"); } }

      /// <summary>
      /// Gets or sets the timestamp.
      /// </summary>
      public DateTime Timestamp { get; set; }

      /// <summary>
      /// Gets a value indicating whether this <see cref="Entry" /> is a file.
      /// </summary>
      public bool IsFile { get { return !IsDirectory; } }

      [EditorBrowsable(EditorBrowsableState.Never)]
      public int HeaderOffset { get; set; }

      [EditorBrowsable(EditorBrowsableState.Never)]
      public int DataOffset { get; set; }
    }

    /// <summary>
    /// CRC32 calculation helper.
    /// </summary>
    public class Crc32Calculator
    {
      private static readonly uint[] Crc32Table =
      {
        0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
        0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
        0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
        0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
        0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
        0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
        0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
        0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
        0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
        0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
        0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
        0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
        0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
        0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
        0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
        0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
        0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
        0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
        0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
        0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
        0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
        0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
        0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
        0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
        0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
        0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
        0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
        0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
        0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
        0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
        0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
        0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
      };

      private uint crcValue = 0xffffffff;

      public uint Crc32 { get { return crcValue ^ 0xffffffff; } }

      public void UpdateWithBlock(byte[] buffer, int numberOfBytes)
      {
        for (var i = 0; i < numberOfBytes; i++)
        {
          crcValue = (crcValue >> 8) ^ Crc32Table[buffer[i] ^ crcValue & 0xff];
        }
      }
    }

    /// <summary>
    /// Provides data for the ExtractProgress event.
    /// </summary>
    public class FileProgressEventArgs : ProgressChangedEventArgs
    {
      /// <summary>
      /// Initializes a new instance of the <see cref="FileProgressEventArgs"/> class.
      /// </summary>
      /// <param name="currentFile">The current file.</param>
      /// <param name="totalFiles">The total files.</param>
      /// <param name="fileName">Name of the file.</param>
      public FileProgressEventArgs(int currentFile, int totalFiles, string fileName)
        : base(totalFiles != 0 ? currentFile * 100 / totalFiles : 100, fileName)
      {
        CurrentFile = currentFile;
        TotalFiles = totalFiles;
        FileName = fileName;
      }

      /// <summary>
      /// Gets the current file.
      /// </summary>
      public int CurrentFile { get; private set; }

      /// <summary>
      /// Gets the total files.
      /// </summary>
      public int TotalFiles { get; private set; }

      /// <summary>
      /// Gets the name of the file.
      /// </summary>
      public string FileName { get; private set; }
    }

    private const int EntrySignature = 0x02014B50;
    private const int FileSignature = 0x04034b50;
    private const int DirectorySignature = 0x06054B50;
    private const int BufferSize = 16 * 1024;

    /// <summary>
    /// Occurs when a file or a directory is extracted from an archive.
    /// </summary>
    public event EventHandler<FileProgressEventArgs> ExtractProgress;

    /// <summary>
    /// Initializes a new instance of the <see cref="Unzip" /> class.
    /// </summary>
    /// <param name="fileName">Name of the file.</param>
    public Unzip(string fileName)
      : this(File.OpenRead(fileName))
    {
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="Unzip" /> class.
    /// </summary>
    /// <param name="stream">The stream.</param>
    public Unzip(Stream stream)
    {
      Stream = stream;
      Reader = new BinaryReader(Stream);
    }

    private Stream Stream { get; set; }

    private BinaryReader Reader { get; set; }

    /// <summary>
    /// Performs application-defined tasks associated with
    /// freeing, releasing, or resetting unmanaged resources.
    /// </summary>
    public void Dispose()
    {
      if (Stream != null)
      {
        Stream.Dispose();
        Stream = null;
      }

      if (Reader != null)
      {
        Reader.Close();
        Reader = null;
      }
    }

    /// <summary>
    /// Extracts the contents of the zip file to the given directory.
    /// </summary>
    /// <param name="directoryName">Name of the directory.</param>
    public void ExtractToDirectory(string directoryName)
    {
      for (int index = 0; index < Entries.Length; index++)
      {
        var entry = Entries[index];

        // create target directory for the file
        var fileName = Path.Combine(directoryName, entry.Name);
        var dirName = Path.GetDirectoryName(fileName);
        Directory.CreateDirectory(dirName);

        // save file if it is not only a directory
        if (!entry.IsDirectory)
        {
          Extract(entry.Name, fileName);
        }

        var extractProgress = ExtractProgress;
        if (extractProgress != null)
        {
          extractProgress(this, new FileProgressEventArgs(index + 1, Entries.Length, entry.Name));
        }
      }
    }

    /// <summary>
    /// Extracts the specified file to the specified name.
    /// </summary>
    /// <param name="fileName">Name of the file in zip archive.</param>
    /// <param name="outputFileName">Name of the output file.</param>
    public void Extract(string fileName, string outputFileName)
    {
      var entry = GetEntry(fileName);

      using (var outStream = File.Create(outputFileName))
      {
        Extract(entry, outStream);
      }

      var fileInfo = new FileInfo(outputFileName);
      if (fileInfo.Length != entry.OriginalSize)
      {
        throw new InvalidDataException(string.Format(
          "Corrupted archive: {0} has an uncompressed size {1} which does not match its expected size {2}",
          outputFileName, fileInfo.Length, entry.OriginalSize));
      }

      File.SetLastWriteTime(outputFileName, entry.Timestamp);
    }

    private Entry GetEntry(string fileName)
    {
      fileName = fileName.Replace("\\", "/").Trim().TrimStart('/');
      var entry = Entries.FirstOrDefault(e => e.Name == fileName);

      if (entry == null)
      {
        throw new FileNotFoundException("File not found in the archive: " + fileName);
      }

      return entry;
    }

    /// <summary>
    /// Extracts the specified file to the output <see cref="Stream"/>.
    /// </summary>
    /// <param name="fileName">Name of the file in zip archive.</param>
    /// <param name="outputStream">The output stream.</param>
    public void Extract(string fileName, Stream outputStream)
    {
      Extract(GetEntry(fileName), outputStream);
    }

    /// <summary>
    /// Extracts the specified entry.
    /// </summary>
    /// <param name="entry">Zip file entry to extract.</param>
    /// <param name="outputStream">The stream to write the data to.</param>
    /// <exception cref="System.InvalidOperationException"> is thrown when the file header signature doesn't match.</exception>
    public void Extract(Entry entry, Stream outputStream)
    {
      // check file signature
      Stream.Seek(entry.HeaderOffset, SeekOrigin.Begin);
      if (Reader.ReadInt32() != FileSignature)
      {
        throw new InvalidDataException("File signature doesn't match.");
      }

      // move to file data
      Stream.Seek(entry.DataOffset, SeekOrigin.Begin);
      var inputStream = Stream;
      if (entry.Deflated)
      {
        inputStream = new DeflateStream(Stream, CompressionMode.Decompress, true);
      }

      // allocate buffer, prepare for CRC32 calculation
      var count = entry.OriginalSize;
      var bufferSize = Math.Min(BufferSize, entry.OriginalSize);
      var buffer = new byte[bufferSize];
      var crc32Calculator = new Crc32Calculator();

      while (count > 0)
      {
        // decompress data
        var read = inputStream.Read(buffer, 0, bufferSize);
        if (read == 0)
        {
          break;
        }

        crc32Calculator.UpdateWithBlock(buffer, read);

        // copy to the output stream
        outputStream.Write(buffer, 0, read);
        count -= read;
      }

      if (crc32Calculator.Crc32 != entry.Crc32)
      {
        throw new InvalidDataException(string.Format(
          "Corrupted archive: CRC32 doesn't match on file {0}: expected {1:x8}, got {2:x8}.",
          entry.Name, entry.Crc32, crc32Calculator.Crc32));
      }
    }

    /// <summary>
    /// Gets the file names.
    /// </summary>
    public IEnumerable<string> FileNames
    {
      get
      {
        return Entries.Select(e => e.Name).Where(f => !f.EndsWith("/")).OrderBy(f => f);
      }
    }

    private Entry[] entries;

    /// <summary>
    /// Gets zip file entries.
    /// </summary>
    public Entry[] Entries
    {
      get
      {
        if (entries == null)
        {
          entries = ReadZipEntries().ToArray();
        }

        return entries;
      }
    }

    private IEnumerable<Entry> ReadZipEntries()
    {
      if (Stream.Length < 22)
      {
        yield break;
      }

      Stream.Seek(-22, SeekOrigin.End);

      // find directory signature
      while (Reader.ReadInt32() != DirectorySignature)
      {
        if (Stream.Position <= 5)
        {
          yield break;
        }

        // move 1 byte back
        Stream.Seek(-5, SeekOrigin.Current);
      }

      // read directory properties
      Stream.Seek(6, SeekOrigin.Current);
      var entries = Reader.ReadUInt16();
      var difSize = Reader.ReadInt32();
      var dirOffset = Reader.ReadUInt32();
      Stream.Seek(dirOffset, SeekOrigin.Begin);

      // read directory entries
      for (int i = 0; i < entries; i++)
      {
        if (Reader.ReadInt32() != EntrySignature)
        {
          continue;
        }

        // read file properties
        // TODO: Replace with a proper class to make this method a lot shorter.
        Reader.ReadInt32();
        bool utf8 = (Reader.ReadInt16() & 0x0800) != 0;
        short method = Reader.ReadInt16();
        int timestamp = Reader.ReadInt32();
        uint crc32 = Reader.ReadUInt32();
        int compressedSize = Reader.ReadInt32();
        int fileSize = Reader.ReadInt32();
        short fileNameSize = Reader.ReadInt16();
        short extraSize = Reader.ReadInt16();
        short commentSize = Reader.ReadInt16();
        int headerOffset = Reader.ReadInt32();
        Reader.ReadInt32();
        int fileHeaderOffset = Reader.ReadInt32();
        var fileNameBytes = Reader.ReadBytes(fileNameSize);
        Stream.Seek(extraSize, SeekOrigin.Current);
        var fileCommentBytes = Reader.ReadBytes(commentSize);
        var fileDataOffset = CalculateFileDataOffset(fileHeaderOffset);

        // decode zip file entry
        var encoder = utf8 ? Encoding.UTF8 : Encoding.Default;
        yield return new Entry
        {
          Name = encoder.GetString(fileNameBytes),
          Comment = encoder.GetString(fileCommentBytes),
          Crc32 = crc32,
          CompressedSize = compressedSize,
          OriginalSize = fileSize,
          HeaderOffset = fileHeaderOffset,
          DataOffset = fileDataOffset,
          Deflated = method == 8,
          Timestamp = ConvertToDateTime(timestamp)
        };
      }
    }

    private int CalculateFileDataOffset(int fileHeaderOffset)
    {
      var position = Stream.Position;
      Stream.Seek(fileHeaderOffset + 26, SeekOrigin.Begin);
      var fileNameSize = Reader.ReadInt16();
      var extraSize = Reader.ReadInt16();

      var fileOffset = (int)Stream.Position + fileNameSize + extraSize;
      Stream.Seek(position, SeekOrigin.Begin);
      return fileOffset;
    }

    /// <summary>
    /// Converts DOS timestamp to a <see cref="DateTime"/> instance.
    /// </summary>
    /// <param name="dosTimestamp">The dos timestamp.</param>
    /// <returns>The <see cref="DateTime"/> instance.</returns>
    public static DateTime ConvertToDateTime(int dosTimestamp)
    {
      return new DateTime((dosTimestamp >> 25) + 1980, (dosTimestamp >> 21) & 15, (dosTimestamp >> 16) & 31,
        (dosTimestamp >> 11) & 31, (dosTimestamp >> 5) & 63, (dosTimestamp & 31) * 2);
    }
  }
}