.Net C# DeflateStream问题

Question

我想知道是否有人能对一个让我发疯的问题有所了解：

我正在编写压缩解压缩测试类。为了测试它，我将数据集序列化到一个内存流中，对其进行压缩，然后解压缩并比较结果。

压缩是很好的，但解压缩是它碰到污垢的地方。这是解压缩功能：

    public static Stream GetUncompressedStreamCopy(Stream inStream)
    {
      Stream outStream = new MemoryStream();

      inStream.Position = 0;

      DeflateStream uncompressStream = new DeflateStream(inStream, 
        CompressionMode.Decompress, true);

      byte[] buffer = new byte[65536];

      int totalread = 0;
      int bytesread = 0;


      do {
        bytesread = uncompressStream.Read(buffer, 0, buffer.Length);
        totalread += bytesread;
        outStream.Write(buffer, 0, bytesread);
        Console.WriteLine("bytesRead: [{0}]\t outStream.Length [{1}]",
        bytesread, outStream.Length);
      } while (bytesread > 0);


      Console.WriteLine("total bytes read [{0}]", totalread);
      outStream.Flush();
      return outStream;
}

对于大小为65536的缓冲区，解压缩流返回的字节总是比未压缩的要少一个字节。

现在，我要谈谈我正在努力解决的第二个问题。对于某些缓冲区大小，uncompressStream.Read返回0，尽管仍有需要提取的压缩数据。

对于这些情况，deflateStream.Read(s)在do{}循环中只返回一次，然后返回等于缓冲区大小的未压缩流，如果将缓冲区大小增加一个字节，则一切正常(丢失字节除外)。

缓冲区大小为65536的输出：(原始未压缩数据为207833)

bytesRead: [65536]       outStream.Length [65536]
bytesRead: [65536]       outStream.Length [131072]
bytesRead: [58472]       outStream.Length [189544]
bytesRead: [18288]       outStream.Length [207832]
bytesRead: [0]           outStream.Length [207832]
total bytes read [207832]

缓冲区大小为189544 (一些神奇的数字，其中的代码坦克)

bytesRead: [189544]      outStream.Length [189544]
bytesRead: [0]           outStream.Length [189544]
total bytes read [189544]
Unompressed stream size 189544

还请注意缓冲区大小65536 ex: bytesRead: 58472的第三次读取，这显然也应该是65536，因为缓冲区上还保留着数据？

任何想法都将受到极大的赞赏。

提亚

• 雅科

Answer 1

您应该始终在压缩流上调用Close()。请注意()是不够的。我怀疑正是由于这个原因，排水流丢失了数据。

Answer 2

我的心灵力量告诉我，你确实有一个工作的解压缩实现，但忘了冲洗压缩流之前。

Answer 3

好吧，我找不到您的问题，但是请遵循我不久前为ICSharpCode.SharpZipLib编写的一些代码；

byte[] compressedData;
using(MemoryStream ms = new MemoryStream())
{
    Deflater deflater = new Deflater(Deflater.BEST_COMPRESSION, true);
    Stream s = new DeflaterOutputStream(ms, deflater);
    s.Write(sendData, 0, sendData.Length);
    s.Close();
    compressedData = (byte[])ms.ToArray();
}

// ...

MemoryStream inflated = new MemoryStream();
using (Stream inflater = new InflaterInputStream(
    inputStream, new Inflater(true)))
{
    int count = 0;
    byte[] deflated = new byte[4096];
    while ((count = inflater.Read(deflated, 0, deflated.Length)) != 0)
    {
        inflated.Write(deflated, 0, count);
    }
    inflated.Seek(0, SeekOrigin.Begin);
}
byte[] content = new byte[inflated.Length];
inflated.Read(content, 0, content.Length);