7z格式采用的LZMA算法，号称具有现今最高压缩率。笔者在nuget上搜索7z，在搜索结果中最终选择了SevenZipSharp来进行压缩/解压。不得不说，SevenZipSharp的API设计得非常方便。

压缩调用：

using (FileStream ostream = new FileStream(outputpath, FileMode.Create, FileAccess.Write)){    using (FileStream istream = new FileStream(inputpath, FileMode.Open, FileAccess.Read))    {        SevenZipCompressor compressor = new SevenZipCompressor();        // 这里可以输入多个文件名/流对        Dictionary
     
       dict = new Dictionary
      
        { { inputpath, istream } };        compressor.CompressStreamDictionary(dict, ostream);    }}
      
     

解压调用：

using (FileStream istream = new FileStream(inputpath, FileMode.Open, FileAccess.Read)){    SevenZip.SevenZipExtractor extractor = new SevenZip.SevenZipExtractor(istream);    extractor.ExtractArchive(outputpath);    // 全部解压到指定目录    using (FileStream ostream = new FileStream(outputpath, FileMode.Create, FileAccess.Write))    {        extractor.ExtractFile(0, ostream);        // 流式解压指定文件    }}

顺便附上zlib的压缩/解压(使用zlib.net库)：

// 压缩static void Compress(string inputpath, string outputpath){    using (FileStream ostream = new FileStream(outputpath, FileMode.Create, FileAccess.Write))    {        using (FileStream istream = new FileStream(inputpath, FileMode.Open, FileAccess.Read))        {            using (ZOutputStream zstream = new ZOutputStream(ostream, zlibConst.Z_BEST_COMPRESSION))            {                CopyStream(istream, zstream);            }        }    }}// 解压static void Decompress(string inputpath, string outputpath){    using (FileStream ostream = new FileStream(outputpath, FileMode.Create, FileAccess.Write))    {        using (FileStream istream = new FileStream(inputpath, FileMode.Open, FileAccess.Read))        {            using (ZOutputStream zstream = new ZOutputStream(ostream))            {                CopyStream(istream, zstream);            }        }    }}static void CopyStream(Stream input, Stream output){    byte[] buffer = new byte[2000];    int len;    while ((len = input.Read(buffer, 0, 2000)) > 0)    {        output.Write(buffer, 0, len);    }    output.Flush();}