1.新建一个网站或者web应用程序，添加一个aspx页面，用于展示天气数据。（这个应该不用细讲吧）

2.在网上找一个免费的天气预报的接口，我用的是Webxml网站的，地址如下:

3.在项目目录下，  引用  —  添加服务引用，弹出对话框，然后输入接口地址，点击前往，命名空间可以改成你想要的，如下图：

 

一般处理程序代码如下：

using System.Web;using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Text; namespace WeatherTest.ashx{    /// 
    /// weatherHandler 的摘要说明    /// 
    public class weatherHandler : IHttpHandler    {        WeatherWsClient.WeatherWSSoapClient client = new WeatherWsClient.WeatherWSSoapClient();        public void ProcessRequest(HttpContext context)        {            context.Response.ContentType = "text/plain";            string[] result = null;            string option = context.Request.Form["option"];            switch (option)            {                case "province":                    result = GetProvinces();                    break;                case "city":                    result = GetCitys(context.Request.Form["provinceid"]);                    break;                case "weather":                    result = GetWeather(context.Request.Form["cityid"], null);                    break;            }            string str = ConvertToString(result, option);             context.Response.Write(str);        }        /// 
        /// 数组转字符串        /// 
        ///         ///         /// 
              private string ConvertToString(string[] result, string option)        {            StringBuilder sb = new StringBuilder();            foreach (string item in result)            {                sb.Append(item+"|");            }            return sb.ToString();        }         /// 
        /// 省份        /// 
        /// 
              private string[] GetProvinces()        {            return client.getRegionProvince();        }        /// 
        /// 城市        /// 
        ///         /// 
              private string[] GetCitys(string provinceid)        {            return client.getSupportCityString(provinceid);        }        /// 
        /// 天气数据        /// 
        ///         ///         /// 
              private string[] GetWeather(string cityid, string userid)        {            return client.getWeather(cityid, userid);        }         public bool IsReusable        {            get            {                return false;            }        }    }}