使用此方法从字符串生成流，(感谢 Cameron MacFarland)

Use this method to generate stream from string, (thanks to Cameron MacFarland)

public Stream GenerateStreamFromString(string s)
{
    MemoryStream stream = new MemoryStream();
    StreamWriter writer = new StreamWriter(stream);
    writer.Write(s);
    writer.Flush();
    stream.Position = 0;
    return stream;
}