private void PackFile(ZipOutputStream zipfile, string filePath, string targetName)
{
FileInfo fileInfo = new FileInfo(filePath);
ZipEntry zipentry = zipEntryFactory.MakeFileEntry(targetName, true);
zipentry.DateTime = fileInfo.LastWriteTime;
zipentry.Size = fileInfo.Length;
zipfile.PutNextEntry(zipentry);
using (FileStream streamReader = File.OpenRead(filePath))
StreamUtils.Copy(streamReader, zipfile, new byte[4096]);
zipfile.CloseEntry();
}