string strInfileName = @"D:\test.txt";
string strOutfileName = @"D:\test.zip";
FileStream fsInfile = new FileStream(strInfileName, FileMode.Open);
byte[] buff = new byte[(int)fsInfile.Length];
fsInfile.Read(buff, 0, buff.Length);
fsInfile.Close();
FileStream fsOutfile = new FileStream(strOutfileName, FileMode.Create);
GZipStream gzStream = new GZipStream(fsOutfile, CompressionMode.Compress, true);
gzStream.Write(buff, 0, buff.Length);
gzStream.Close();
fsOutfile.Close();
我在网上查到的关于GZipStream压缩的例子大多是这样的.首先把要压缩的文件内容全部输入到byte[]中,然后再将解压后的内容输入到文件流中.但这样的话有多大文件就要占用多大内存.我想把文件一部分一部分的读入再一部分一部分的将压缩内容输出到文件.但不知道怎么操作.
using (FileStream inStream = new FileStream("", FileMode.Open))
using (FileStream outStream = new FileStream("", FileMode.OpenOrCreate))
using (GZipStream gzipStream = new GZipStream(outStream, CompressionMode.Compress))
{
inStream.CopyTo(gzipStream);
//.net4 以前就读一部份,写一部分,直到完成。
}
Private Shared Sub exeCompress(ByVal orgStream As System.IO.Stream, ByVal cmpStream As System.IO.Stream)
Dim zipStream As System.IO.Compression.GZipStream = New System.IO.Compression.GZipStream(cmpStream, System.IO.Compression.CompressionMode.Compress)
Dim buffer As Byte() = New Byte(1024) {}
While True
Dim bytesRead As Integer = orgStream.Read(buffer, 0, 1024)
If bytesRead = 0 Then
Exit While
End If
zipStream.Write(buffer, 0, bytesRead)
End While
zipStream.Flush()
zipStream.Close()
End Sub
GZipStream在输出结果的时候,好像首先会写入GZIP文件头部信息.在最后调用close方法的时候,还会写入GZIP文件尾部信息,尾部包含原文件的大小和校验和.那么1.如果一部分一部分的压缩的话,而不是一次性进行的话,那么它是按什么来算校验和大小的呢?
2.另外,我每一部分设置成多大才会达到最好的压缩效果呢?