Compression stream appears empty
-
04-06-2021 - |
Question
I need to compress a file using GZip by batch of specified size (not in a whole). I can successfuly fill the byte[] buffer, but after copying it into the compression stream, it just leaves the output stream empty.
public void Compress(string source, string output)
{
FileInfo fi = new FileInfo(source);
byte[] buffer = new byte[BufferSize];
int total, current = 0;
using (FileStream inFile = fi.OpenRead())
{
using (FileStream outFile = File.Create(output + ".gz"))
{
while ((total = inFile.Read(buffer, 0, buffer.Length)) != 0)
{
using (MemoryStream compressedStream = new MemoryStream())
{
using (MemoryStream bufferStream = new MemoryStream())
{
CopyToStream(buffer, bufferStream);
using (GZipStream Compress = new GZipStream(compressedStream, CompressionMode.Compress, true))
{
bufferStream.Position = 0;
bufferStream.CopyTo(Compress);
current += total;
}
compressedStream.Position = 0;
compressedStream.CopyTo(outFile);
}
}
}
}
}
}
static void CopyToStream(byte[] buffer, Stream output)
{
output.Write(buffer, 0, buffer.Length);
}
Solution
You need to rewind compressedStream by setting Position=0 before compressedStream.CopyTo(outFile);
.
OTHER TIPS
You are trying to over complicate things... You do not require additional MemoryStreams or buffers...
Taken from the MSDN... http://msdn.microsoft.com/en-us/library/system.io.compression.gzipstream.aspx
public static void Compress(FileInfo fi)
{
// Get the stream of the source file.
using (FileStream inFile = fi.OpenRead())
{
// Prevent compressing hidden and
// already compressed files.
if ((File.GetAttributes(fi.FullName)
& FileAttributes.Hidden)
!= FileAttributes.Hidden & fi.Extension != ".gz")
{
// Create the compressed file.
using (FileStream outFile =
File.Create(fi.FullName + ".gz"))
{
using (GZipStream Compress =
new GZipStream(outFile,
CompressionMode.Compress))
{
// Copy the source file into
// the compression stream.
inFile.CopyTo(Compress);
Console.WriteLine("Compressed {0} from {1} to {2} bytes.",
fi.Name, fi.Length.ToString(), outFile.Length.ToString());
}
}
}
}
}
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