使用DeflateStream压缩byte []时出现问题 [英] Problem compressing byte[] with DeflateStream

问题描述

大家好

我需要使用System.IO.Compression.DeflateStream
压缩byte []
这是我到目前为止的代码:

Hey guys

I need to compress a byte[] with the System.IO.Compression.DeflateStream

Here''s the code I have so far:

byte[] uncompressedCsvFile = File.ReadAllBytes(csvFileName);
byte[] compressedCsvFile;

using (MemoryStream outStream = new MemoryStream())
{
    using (DeflateStream compress = new DeflateStream(outStream, CompressionMode.Compress, true))
    {
        compress.Write(uncompressedCsvFile, 0, uncompressedCsvFile.Length);
        compress.Flush();
        compress.Close();
    }

    compressedCsvFile = new byte[outStream.Length];
    outStream.Read(compressedCsvFile, 0, (int)outStream.Length);
}

outStream.Lentgh比未压缩的byte []小得多，但是在我尝试读取MemoryStream之后，我的压缩的byte []仅包含0.
在调试器中，我注意到在outStream的非公共成员中，_buffer是预期的大小，并且包含0以外的字节.

我在读取内存流时做错什么了吗?

注意:我需要压缩此数组以通过电线发送它，并在另一端对其进行解压缩以使用.将其压缩为文件不会解决我的问题.

outStream.Lentgh is much smaller than the uncompressed byte[], but after i try to read the MemoryStream my compressed byte[] just contains 0''s.

In the debuger I noticed that in outStream''s non public members _buffer is the expected size and contains bytes other than 0.

Am I doing something wrong reading the memory stream?

NOTE: I need to compress this array to send it over the wire and decompress it on the other side to work with. Compressing it to a file won''t solve my problem.

推荐答案

您的流在阅读时已结束.试试这个:

Your stream is at the end when you read it. Try this:

compressedCsvFile = new byte[outStream.Length];
if (outStream.CanSeek)
    {
    outStream.Seek(0, SeekOrigin.Begin);
    }
outStream.Read(compressedCsvFile, 0, (int)outStream.Length);

由于内存流始终可以查找，因此您不需要进行CanSeek测试，但是值得进行此测试.

You shouldn''t need the CanSeek test since a memory stream can always seek, but it is worth including.

问题在于如何从内存流中获取数据. outStream.ToArray();返回压缩的字节.

工作压缩方式:

The problem was getting the data out of the memory stream. outStream.ToArray(); returnes the compressed bytes.

Working Compression Method:

public static byte[] CompressData(string fileName)
{
    byte[] uncompressedFileData = new byte[0];
    byte[] compressedFileData = new byte[0];

    try
    {
        var stopwatch = new Stopwatch();
        stopwatch.Reset();
        stopwatch.Start();

        if (!File.Exists(fileName))
        {
            throw new FileNotFoundException(fileName + " not found");
        }

        uncompressedFileData = File.ReadAllBytes(fileName);

        using (var outStream = new MemoryStream())
        {
            using (var compress = new DeflateStream(outStream, CompressionMode.Compress, true))
            {
                compress.Write(uncompressedFileData, 0, uncompressedFileData.Length);
                compress.Flush();
                compress.Close();
            }
            compressedFileData = outStream.ToArray();
        }

        stopwatch.Stop();
#if DEBUG
        Console.WriteLine("Compressed {0} bytes to {1} bytes in {2} seconds", uncompressedFileData.Length, compressedFileData.Length, stopwatch.Elapsed.TotalSeconds);
#endif
    }
    catch (Exception ex)
    {
        m_Log.Error(ex.Message, ex);
    }

    return compressedFileData;
}

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