Console.WriteLine("压缩文件...............");
      using (FileStream fr = File.OpenRead("d:\\test.txt"))
      {
        using (FileStream fw = File.OpenWrite("d:\\test.zip"))
        {
          using (GZipStream gz = new GZipStream(fw, CompressionMode.Compress))
          {

            byte[] by = new byte[1024 * 1024];
            int r = fr.Read(by, 0, by.Length);
            while (r > 0)
            {
              gz.Write(by, 0, r);
              r = fr.Read(by, 0, r);
            }
          }
        }
      }
      Console.WriteLine("压缩完成。");


      Console.WriteLine("解压文件...............");
      using (FileStream fr = File.OpenRead("d:\\test.zip"))
      {
        using (GZipStream gz = new GZipStream(fr, CompressionMode.Decompress))
        {
          using (FileStream fw = File.OpenWrite("d:\\test2.txt"))
          {

            byte[] by = new byte[1024 * 1024];
            int r = gz.Read(by, 0, by.Length);
            while (r > 0)
            {
              fw.Write(by, 0, r);
              r = gz.Read(by, 0, r);
            }
          }
        }
      }

Console.WriteLine("解压完成。");
Console.ReadKey();