//using System.IO;
//using System.IO.Compression;

/// <summary>
/// GZipStream压缩字符串
/// </summary>
/// <param name="str"></param>
/// <returns></returns>
public Stream GZipCompress(string str)
{
    byte[] buffer = System.Text.Encoding.UTF8.GetBytes(str);
    MemoryStream msReturn;

    using (MemoryStream msTemp = new MemoryStream())
    {
        using (GZipStream gz = new GZipStream(msTemp, CompressionMode.Compress, true))
        {
            gz.Write(buffer, 0, buffer.Length);
            gz.Close();

            msReturn = new MemoryStream(msTemp.GetBuffer(), 0, (int)msTemp.Length);
        }
    }

    return msReturn;
}

/// <summary>
/// GZipStream解压字符串
/// </summary>
/// <param name="stream"></param>
/// <returns></returns>
public string GZipDecompress(Stream stream)
{
    byte[] buffer = new byte[100];
    int length = 0;

    using (GZipStream gz = new GZipStream(stream, CompressionMode.Decompress))
    {
        using (MemoryStream msTemp = new MemoryStream())
        {
            while ((length = gz.Read(buffer, 0, buffer.Length)) != 0)
            {
                msTemp.Write(buffer, 0, length);
            }

            return System.Text.Encoding.UTF8.GetString(msTemp.ToArray());
        }
        
    }
}