根据这个链接,wopr告诉我们如何使用7zsdk(How do I create 7-Zip archives with .NET?)使用lmza(7z压缩算法)压缩文件。
using SevenZip.Compression.LZMA;
private static void CompressFileLZMA(string inFile, string outFile)
{
SevenZip.Compression.LZMA.Encoder coder = new SevenZip.Compression.LZMA.Encoder();
using (FileStream input = new FileStream(inFile, FileMode.Open))
{
using (FileStream output = new FileStream(outFile, FileMode.Create))
{
coder.Code(input, output, -1, -1, null);
output.Flush();
}
}
}
但是如何减压呢?
我尝试:
private static void DecompressFileLZMA(string inFile, string outFile)
{
SevenZip.Compression.LZMA.Decoder coder = new SevenZip.Compression.LZMA.Decoder();
using (FileStream input = new FileStream(inFile, FileMode.Open))
{
using (FileStream output = new FileStream(outFile, FileMode.Create))
{
coder.Code(input, output, input.Length, -1, null);
output.Flush();
}
}
}
但没有成功。
你有一个有效的例子吗?
谢谢
PS:
根据其他代码,解码器似乎需要一个头,文件开头的字典才能工作。由Koders生成的文件不是7Z存档。
public static void Decompress(Stream inStream, Stream outStream)
{
byte[] properties = new byte[5];
inStream.Read(properties, 0, 5);
SevenZip.Compression.LZMA.Decoder decoder = new SevenZip.Compression.LZMA.Decoder();
decoder.SetDecoderProperties(properties);
long outSize = 0;
for (int i = 0; i < 8; i++)
{
int v = inStream.ReadByte();
outSize |= ((long)(byte)v) << (8 * i);
}
long compressedSize = inStream.Length - inStream.Position;
decoder.Code(inStream, outStream, compressedSize, outSize, null);
}
超大尺寸的计算方法与它们的压缩方法相同。但是如何计算输出大小呢?
最佳答案:
这个问题有点老套了,但谷歌没有给出一个令人满意的答案,所以这是给那些像我一样仍在寻求答案的人的。如果您查看sdk的lmzaonly文件夹,就会看到压缩和解压缩文件的代码。以它为例,您似乎需要编写和读取编码器属性,并将文件大小解压缩到输出文件:
private static void CompressFileLZMA(string inFile, string outFile)
{
SevenZip.Compression.LZMA.Encoder coder = new SevenZip.Compression.LZMA.Encoder();
FileStream input = new FileStream(inFile, FileMode.Open);
FileStream output = new FileStream(outFile, FileMode.Create);
// Write the encoder properties
coder.WriteCoderProperties(output);
// Write the decompressed file size.
output.Write(BitConverter.GetBytes(input.Length), 0, 8);
// Encode the file.
coder.Code(input, output, input.Length, -1, null);
output.Flush();
output.Close();
}
private static void DecompressFileLZMA(string inFile, string outFile)
{
SevenZip.Compression.LZMA.Decoder coder = new SevenZip.Compression.LZMA.Decoder();
FileStream input = new FileStream(inFile, FileMode.Open);
FileStream output = new FileStream(outFile, FileMode.Create);
// Read the decoder properties
byte[] properties = new byte[5];
input.Read(properties, 0, 5);
// Read in the decompress file size.
byte [] fileLengthBytes = new byte[8];
input.Read(fileLengthBytes, 0, 8);
long fileLength = BitConverter.ToInt64(fileLengthBytes, 0);
coder.SetDecoderProperties(properties);
coder.Code(input, output, input.Length, fileLength, null);
output.Flush();
output.Close();
}
请注意,以这种方式创建的文件也可以由7zip程序提取,但不会保留其文件名或任何其他元数据。