/// <summary>
/// 分析 url 字符串中的参数信息
/// </summary>
/// <param name="url">输入的 URL</param>
/// <param name="baseUrl">输出 URL 的基础部分</param>
/// <param name="nvc">输出分析后得到的 (参数名,参数值) 的集合</param>
public static void ParseUrl(string url, out string baseUrl, out NameValueCollection nvc)
{
  if (url == null)
 throw new ArgumentNullException("url");
  nvc = new NameValueCollection();
  baseUrl = "";
  if (url == "")
 return;
  int questionMarkIndex = url.IndexOf('?');
  if (questionMarkIndex == -1)
  {
 baseUrl = url;
 return;
  }
  baseUrl = url.Substring(0, questionMarkIndex);
  if (questionMarkIndex == url.Length - 1)
 return;
  string ps = url.Substring(questionMarkIndex + 1);
  // 开始分析参数对  
  Regex re = new Regex(@"(^|&)?(\w+)=([^&]+)(&|$)?",RegexOptions.Compiled);
  MatchCollection mc = re.Matches(ps);
  foreach (Match m in mc)
  {
 nvc.Add(m.Result("$2").ToLower(), m.Result("$3"));
  }
}