获得Google搜索字符串中的关键字

  /// <summary>
  /// 获得Google搜索字符串中的关键字
  /// </summary>
  /// <returns></returns>
  public string GetKeywords(string GetUrl)
  {
   //string GetUrl = "http://www.google.cn/search?hl=zh-CN&q=%E7%8E%AF%E7%90%83%E5%A4%96%E6%B1%87%E7%BD%91&btnG=Google+%E6%90%9C%E7%B4%A2&meta=&aq=f";
   if (GetUrl.Contains("q="))
   {
    string strPara = "q=";
    string GetKeywords = "";
    int intLength = GetUrl.Length;//url地址长度
    int intGetStartPostion = GetUrl.IndexOf(strPara);//找到关键字参数位置
    int toGetEndPostion = GetUrl.IndexOf("&", intGetStartPostion);//查找关键字参数后面一个参数的位置
    if (toGetEndPostion <= 0)//如果wd是组后一个参数时
    {
     GetKeywords = GetUrl.Substring(intGetStartPostion + 2, intLength - intGetStartPostion - 2);
    }
    else
    {
     GetKeywords = GetUrl.Substring(intGetStartPostion + 2, toGetEndPostion - intGetStartPostion - 2);
    }
    //对获取到的编码字符串进行解码
    GetKeywords =System.Web.HttpUtility.UrlDecode(GetKeywords, System.Text.Encoding.GetEncoding("utf-8"));

    Console.Write(GetKeywords);
   // MessageBox.Show(GetKeywords,this.Text);
    
    return GetKeywords;
   }
   else
    return "";
  }