利用YAHOO公开API做天气预报Web服务

系列文章导航：

创建一个示例和WebMethod特性解析

WebService特性和数组类型解析

类和结构体解析

利用YAHOO公开API做天气预报Web服务

Webservice 的设计和模式

Remoting和Webservice的区别

其中最重要的是后面的几行，查询当天和第二天的天气情况，我们要获取的天气信息就在里面，代码如下：

     <yweather:forecast day="Tue" date="14 Oct 2008" low="47" high="68" text
="Mostly Cloudy" code="28" />
      <yweather:forecast day="Wed" date="15 Oct 2008" low="44" high="70" text
="Partly Cloudy" code="30" />

我们所需要用到的Node是/rss/channel/item/yweather: forecast；这个节点里的东西是我们需要的。

知道了这些，我们接下来要做的就是在VS中建立WEB服务，并添加下面的代码：

namespace Weather
{
    /**//// <summary>
    /// Weather 的摘要说明
    /// </summary>
    [WebService(Name = "天气预报Web服务", Namespace = "http://www.h2bbs.com/WebService/Weather.asmx", Description = "利用YAHOO公开的API接口，在Web服务实现公开的天气预报调用服务。")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [ToolboxItem(false)]
    public class Weather : System.Web.Services.WebService
    {
        [WebMethod(Description = "根据城市的名称返回该城市的天气预报情况，只能查询省会和直辖市的天气情况。")]
        public DataSet GetWeather(string strCityName)
        {
            string strXml = "http://xml.weather.yahoo.com/forecastrss?p=CHXX" + CityNameToCityNum(strCityName);

            XmlDocument Weather = new XmlDocument();
            Weather.Load(strXml);

            XmlNamespaceManager namespacemanager = new
XmlNamespaceManager(Weather.NameTable);
            namespacemanager.AddNamespace("yweather",
"http://xml.weather.yahoo.com/ns/rss/1.0");
            XmlNodeList nodes = Weather.SelectNodes("/rss/channel/item/yweather:forecast", namespacemanager);

            //XmlNodeList nodes = Weather.GetElementsByTagName("forecast", "http://xml.weather.yahoo.com/ns/rss/1.0");

            DataSet dstWeather = new DataSet();
            DataTable dtblWeather = new DataTable("Weather");
            dstWeather.Tables.Add(dtblWeather);

            dstWeather.Tables["Weather"].Columns.Add("Date", typeof(string));
            dstWeather.Tables["Weather"].Columns.Add("Week", typeof(string));
            dstWeather.Tables["Weather"].Columns.Add("Weather", typeof(string));
            dstWeather.Tables["Weather"].Columns.Add("Tlow", typeof(string));
            dstWeather.Tables["Weather"].Columns.Add("Thigh", typeof(string));

            if (nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    DataRow drowWeather = dstWeather.Tables["Weather"].NewRow();

                    drowWeather["Date"] = EmonthToCmonth(node.SelectSingleNode
("@date").Value.ToString());
                    drowWeather["Week"] = EweekToCweek(node.SelectSingleNode
("@day").Value.ToString()) + "(" + node.SelectSingleNode("@day").Value.ToString()
+ ")";
                    drowWeather["Weather"] = node.SelectSingleNode("@text").Value;
                    drowWeather["Tlow"] = FToC(int.Parse(node.SelectSingleNode
("@low").Value)) + "℃";
                    drowWeather["Thigh"] = FToC(int.Parse(node.SelectSingleNode
("@high").Value)) + "℃";

                    dstWeather.Tables["Weather"].Rows.Add(drowWeather);
                }

                return dstWeather;
            }
            else
            {
                DataRow drowNone = dstWeather.Tables["Weather"].NewRow();
                drowNone["Week"] = "None";
                drowNone["Weather"] = "None";
                drowNone["Tlow"] = "None";
                drowNone["Thigh"] = "None";

                dstWeather.Tables["Weather"].Rows.Add(drowNone);
                return dstWeather;
            }

            return dstWeather;
        }

        /**//// <summary>
        /// 从华氏转换成摄氏
        /// </summary>
        /// <param name="f">华氏度</param>
        /// <returns></returns>
        private string FToC(int f)
        {
            return Math.Round((f - 32) / 1.8, 1).ToString();
        }

        /**//// <summary>
        /// 从星期英文缩写转汉字
        /// </summary>
        /// <param name="strEweek">星期的英文缩写</param>
        /// <returns></returns>
        private string EweekToCweek(string strEweek)
        {
            switch (strEweek)
            {
                case "Mon":
                    return "星期一";
                    break;
                case "Tue":
                    return "星期二";
                    break;
                case "Wed":
                    return "星期三";
                    break;
                case "Thu":
                    return "星期四";
                    break;
                case "Fri":
                    return "星期五";
                    break;
                case "Sat":
                    return "星期六";
                    break;
                case "Sun":
                    return "星期日";
                    break;
                default:
                    return "传参错误";
                    break;
            }
        }

        /**//// <summary>
        /// 从月英文缩写转汉字
        /// </summary>
        /// <param name="strReplace">需要替换的年月日</param>
        /// <returns></returns>
        private string EmonthToCmonth(string strReplace)
        {
            return Convert.ToDateTime(strReplace).ToString("yyyy年MM月dd日");
        }

        /**//// <summary>
        /// 根据城市名称返回城市编号
        /// </summary>
        /// <param name="strCityName">城市名称</param>
        /// <returns></returns>
        private string CityNameToCityNum(string strCityNameToNum)
        {
            //中国各个省会和直辖市对应的查询代码
            Hashtable htWeather = new Hashtable();
            htWeather.Add("北京", "0008");
            htWeather.Add("天津", "0133");
            htWeather.Add("杭州", "0044");
            htWeather.Add("合肥", "0448");
            htWeather.Add("上海", "0116");
            htWeather.Add("福州", "0031");
            htWeather.Add("重庆", "0017");
            htWeather.Add("南昌", "0097");
            htWeather.Add("香港", "0049");
            htWeather.Add("济南", "0064");
            htWeather.Add("澳门", "0512");
            htWeather.Add("郑州", "0165");
            htWeather.Add("呼和浩特", "0249");
            htWeather.Add("乌鲁木齐", "0135");
            htWeather.Add("长沙", "0013");
            htWeather.Add("银川", "0259");
            htWeather.Add("广州", "0037");
            htWeather.Add("拉萨", "0080");
            htWeather.Add("海口", "0502");
            htWeather.Add("南宁", "0100");
            htWeather.Add("成都", "0016");
            htWeather.Add("石家庄", "0122");
            htWeather.Add("贵阳", "0039");
            htWeather.Add("太原", "0129");
            htWeather.Add("昆明", "0076");
            htWeather.Add("沈阳", "0119");
            htWeather.Add("西安", "0141");
            htWeather.Add("长春", "0010");
            htWeather.Add("兰州", "0079");
            htWeather.Add("西宁", "0236");
            htWeather.Add("南京", "0099");

            object cityNum = htWeather[strCityNameToNum];

            if (cityNum == null)
            {
                return "City not found";
            }
            else
            {
                return cityNum.ToString();
            }
        }
    }
}

别忘了"using System.Xml;"哦！