c# – 原始流有数据,Deflate返回零字节

我正在阅读数据(adCenter报告,因为它发生),它应该是压缩的.用普通的流读取内容,我得到几千字节的乱码,所以这似乎是合理的.所以我将流提供给DeflateStream.

首先,它报告“块长度与其补码不匹配”.简短的搜索表明存在一个双字节前缀,实际上如果我在打开DeflateStream之前调用两次ReadByte(),则异常就会消失.

但是,DeflateStream现在根本不返回任何内容.我已经花了大半个时间在这上面追逐线索,没有运气.帮助我,StackOverflow,你是我唯一的希望！谁能告诉我我错过了什么？

这是代码.当然,我在测试时只启用了两个注释块中的一个.

_results = new List<string[]>();
using (Stream compressed = response.GetResponseStream())
  {
  // Skip the zlib prefix,which conflicts with the deflate specification
  compressed.ReadByte();  compressed.ReadByte();

  // Reports reading 3,000-odd bytes,followed by random characters
  /*byte[]  buffer    = new byte[4096];
  int     bytesRead = compressed.Read(buffer,4096);
  Console.WriteLine("Read {0} bytes.",bytesRead.ToString("#,##0"));
  string  content   = Encoding.ASCII.GetString(buffer,bytesRead);
  Console.WriteLine(content);*/

  using (DeflateStream decompressed = new DeflateStream(compressed,CompressionMode.Decompress))
    {
    // Reports reading 0 bytes,and no output
    /*byte[]  buffer    = new byte[4096];
    int     bytesRead = decompressed.Read(buffer,4096);
    Console.WriteLine("Read {0} bytes.",##0"));
    string  content   = Encoding.ASCII.GetString(buffer,bytesRead);
    Console.WriteLine(content);*/

    using (StreamReader reader = new StreamReader(decompressed))
      while (reader.EndOfStream == false)
        _results.Add(reader.ReadLine().Split('\t'));
    }
  }

正如您可能从最后一行猜测的那样,解压缩的内容应该是TDT.

只是为了好玩,我尝试用GZipStream解压缩,但它报告了幻数不正确. MS’文档只是说“下载的报告是使用zip压缩压缩的.您必须先解压缩报告才能使用其内容.”

这是最终有效的代码.我不得不将内容保存到文件中并将其重新读入.这似乎不合理,但对于我正在使用的少量数据,这是可以接受的,我会接受它！

WebRequest   request  = HttpWebRequest.Create(reportURL);
WebResponse  response = request.GetResponse();

_results = new List<string[]>();
using (Stream compressed = response.GetResponseStream())
  {
  // Save the content to a temporary location
  string  zipFilePath = @"\\Server\Folder\adCenter\Temp.zip";
  using (StreamWriter file = new StreamWriter(zipFilePath))
    {
    compressed.copyTo(file.BaseStream);
    file.Flush();
    }

  // Get the first file from the temporary zip
  ZipFile  zipFile = ZipFile.Read(zipFilePath);
  if (zipFile.Entries.Count > 1)  throw new ApplicationException("Found " + zipFile.Entries.Count.ToString("#,##0") + " entries in the report; expected 1.");
  ZipEntry  report = zipFile[0];

  // Extract the data
  using (MemoryStream decompressed = new MemoryStream())
    {
    report.Extract(decompressed);
    decompressed.Position = 0;  // Note that the stream does NOT start at the beginning
    using (StreamReader reader = new StreamReader(decompressed))
      while (reader.EndOfStream == false)
        _results.Add(reader.ReadLine().Split('\t'));
    }
  }

解决方法

您会发现DeflateStream在解压缩的数据方面受到很大限制.事实上,如果您期望整个文件,它将毫无用处.
ZIP文件存在大量(大多数是小的)变体,而DeflateStream只会与其中的两个或三个相处.

最好的方法是使用专用库来读取Zip文件/流,如DotNetZip或SharpZipLib(有点不受维护).

c# – 原始流有数据,Deflate返回零字节

解决方法

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