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Question

我正在尝试使用SevenZipSharp来压缩和解压缩内存流。压缩工作正常，但减压不正常。我认为SevenZipSharp无法从流中找出存档类型。

SevenZipCompressor compress = new SevenZip.SevenZipCompressor();
compress.CompressionLevel = CompressionLevel.Normal;
compress.CompressionMethod = CompressionMethod.Lzma
using (MemoryStream memStream = new MemoryStream())
{
    compress.CompressFiles(memStream, @"d:Temp1MyFile.bmp");
    using (FileStream file = new FileStream(@"d:arch.7z", FileMode.Create, System.IO.FileAccess.Write))
    {
        memStream.CopyTo(file);
    }
}
//works till here, file is created
Console.Read();
using (FileStream file = new FileStream(@"d:arch.7z", FileMode.Open, System.IO.FileAccess.Read))
{
    using (MemoryStream memStream = new MemoryStream())
    {
        file.CopyTo(memStream);
        //throws exception here on this line
        using (var extractor = new SevenZipExtractor(memStream))
        {
            extractor.ExtractFiles(@"d:x", 0);
        }
    }
}

Answer 1

尝试查看是否可以使用 7Zip 客户端加载输出文件。我猜它会失败。

问题在于写入内存流。假设，您将 100 个字节写入流，它将位于位置 100。使用 CopyTo 时，将从当前位置复制流，而不是从流的开头复制流。

因此，您必须在读取/写入后将位置重置为 0，以允许下一个读取器读取所有数据。例如，在创建 7Zip 文件时：

using (MemoryStream memStream = new MemoryStream())
{
    // Position starts at 0
    compress.CompressFiles(memStream, @"d:Temp1MyFile.bmp");
    // Position is now N
    memStream.Position = 0; // <-- Reset the position to 0.
    using (FileStream file = new FileStream(@"d:arch.7z", FileMode.Create, System.IO.FileAccess.Write))
    {
        // Will copy all data in the stream from current position till the end of the stream.
        memStream.CopyTo(file);
    }
}