解压缩 MemoryStream（包含 zip 文件）并获取文件

Question

我有一个内存流，其中包含byte[] 格式的 zip 文件。有什么方法可以解压缩这个内存流，而不需要将文件写入磁盘？

一般来说，我使用ICSharpCode.SharpZipLib.Zip.FastZip 来解压缩文件，但有什么方法可以解压缩内存流，可能是根据存在的文件/文件夹将文件存储为另一个MemoryStream 或byte[] 格式在压缩包里？

在这种情况下，我可以通过什么方式使用 Memorymapped 文件功能？

Answer 1

是的，.Net 4.5 now supports more Zip functionality。

这是基于您的描述的代码示例。

在您的项目中，右键单击 References 文件夹并添加对 System.IO.Compression

的引用

using System.IO.Compression;

Stream data = new MemoryStream(); // The original data
Stream unzippedEntryStream; // Unzipped data from a file in the archive

ZipArchive archive = new ZipArchive(data);
foreach (ZipArchiveEntry entry in archive.Entries)
{
    if(entry.FullName.EndsWith(".txt", StringComparison.OrdinalIgnoreCase))
    {
         unzippedEntryStream = entry.Open(); // .Open will return a stream
         // Process entry data here
    }
}

希望这会有所帮助。

Answer 2

我们使用DotNetZip，我可以将压缩文件的内容从Stream 解压缩到内存中。下面是从流 (LocalCatalogZip) 中提取特定命名文件并返回流以读取该文件的示例代码，但很容易对其进行扩展。

private static MemoryStream UnZipCatalog()
{
    MemoryStream data = new MemoryStream();
    using (ZipFile zip = ZipFile.Read(LocalCatalogZip))
    {
        zip["ListingExport.txt"].Extract(data);
    }
    data.Seek(0, SeekOrigin.Begin);
    return data;
}

这不是您现在使用的库，但如果您可以更改，您可以获得该功能。

---

这是一个变体，它将为 zip 文件的每个文件的内容返回 Dictionary<string,MemoryStream>。

private static Dictionary<string,MemoryStream> UnZipToMemory()
{
    var result = new Dictionary<string,MemoryStream>();
    using (ZipFile zip = ZipFile.Read(LocalCatalogZip))
    {
        foreach (ZipEntry e in zip)
        {
            MemoryStream data = new MemoryStream();
            e.Extract(data);
            result.Add(e.FileName, data);
        }
    }

    return result;
}

Answer 3

我刚刚遇到了类似的问题，我发现我认为似乎相当优雅的答案是使用 #ZipLib（可使用 nuget）并执行以下操作：

private byte[] GetUncompressedPayload(byte[] data)
{
    using (var outputStream = new MemoryStream())
    using (var inputStream = new MemoryStream(data))
    {
        using (var zipInputStream = new ZipInputStream(inputStream))
        {
            zipInputStream.GetNextEntry();
            zipInputStream.CopyTo(outputStream);
        }
        return outputStream.ToArray();
    }
}

这似乎是一种享受。希望这会有所帮助。

Answer 4

是的，从使用 FastZip 更改为 new ZipFile(stream)，但这仅在您的流可以搜索时才有效。 （只需在new ZipFile(fs); 中使用您的 MemoryStream，而不是像示例中那样读取文件流。）

C#
using ICSharpCode.SharpZipLib.Core;
using ICSharpCode.SharpZipLib.Zip;

public void ExtractZipFile(string archiveFilenameIn, string password, string outFolder) {
    ZipFile zf = null;
    try {
        FileStream fs = File.OpenRead(archiveFilenameIn);
        zf = new ZipFile(fs);
        if (!String.IsNullOrEmpty(password)) {
            zf.Password = password;     // AES encrypted entries are handled automatically
        }
        foreach (ZipEntry zipEntry in zf) {
            if (!zipEntry.IsFile) {
                continue;           // Ignore directories
            }
            String entryFileName = zipEntry.Name;
            // to remove the folder from the entry:- entryFileName = Path.GetFileName(entryFileName);
            // Optionally match entrynames against a selection list here to skip as desired.
            // The unpacked length is available in the zipEntry.Size property.

            byte[] buffer = new byte[4096];     // 4K is optimum
            Stream zipStream = zf.GetInputStream(zipEntry);

            // Manipulate the output filename here as desired.
            String fullZipToPath = Path.Combine(outFolder, entryFileName);
            string directoryName = Path.GetDirectoryName(fullZipToPath);
            if (directoryName.Length > 0)
                Directory.CreateDirectory(directoryName);

            // Unzip file in buffered chunks. This is just as fast as unpacking to a buffer the full size
            // of the file, but does not waste memory.
            // The "using" will close the stream even if an exception occurs.
            using (FileStream streamWriter = File.Create(fullZipToPath)) {
                StreamUtils.Copy(zipStream, streamWriter, buffer);
            }
        }
    } finally {
        if (zf != null) {
            zf.IsStreamOwner = true; // Makes close also shut the underlying stream
            zf.Close(); // Ensure we release resources
        }
    }
}

---

如果您使用的是不可搜索的流，请使用 ZipInputStream。

// Calling example:
    WebClient webClient = new WebClient();
    Stream data = webClient.OpenRead("http://www.example.com/test.zip");
    // This stream cannot be opened with the ZipFile class because CanSeek is false.
    UnzipFromStream(data, @"c:\temp");

public void UnzipFromStream(Stream zipStream, string outFolder) {

    ZipInputStream zipInputStream = new ZipInputStream(zipStream);
    ZipEntry zipEntry = zipInputStream.GetNextEntry();
    while (zipEntry != null) {
        String entryFileName = zipEntry.Name;
        // to remove the folder from the entry:- entryFileName = Path.GetFileName(entryFileName);
        // Optionally match entrynames against a selection list here to skip as desired.
        // The unpacked length is available in the zipEntry.Size property.

        byte[] buffer = new byte[4096];     // 4K is optimum

        // Manipulate the output filename here as desired.
        String fullZipToPath = Path.Combine(outFolder, entryFileName);
        string directoryName = Path.GetDirectoryName(fullZipToPath);
        if (directoryName.Length > 0)
            Directory.CreateDirectory(directoryName);

        // Unzip file in buffered chunks. This is just as fast as unpacking to a buffer the full size
        // of the file, but does not waste memory.
        // The "using" will close the stream even if an exception occurs.
        using (FileStream streamWriter = File.Create(fullZipToPath)) {
            StreamUtils.Copy(zipInputStream, streamWriter, buffer);
        }
        zipEntry = zipInputStream.GetNextEntry();
    }
}

来自ICSharpCode Wiki的示例