百度地图热力图--批量地址转换应用（基于百度api）

需求：把外卖订餐地址做个用户分布热力图

思路分析：第一步去百度地图api开放平台找例子 http://lbsyun.baidu.com/jsdemo.htm#c1_15

首先从百度API的demo例子参考静态页面，其中数据格式是

然后我们就想把数据库里的地址批量转换但是百度API没有提供批量转换的接口。
但是我们找到了百度webapi单个地址转换的接口

利用这个接口，在后台读取地址和统计个数，返回一个json

用HttpWebRequest去发起get请求返回json,在把返回的json转成对象

这里套了三层，所以数据结构构造成这样（一开始不这么写获取是null）

 

单个地址转换写好了，下面用一个list<T>装一下，foreach遍历依次赋值，用个一般处理程序得到json

最后把前台界面的数组换成ajax请求数据，要把async设置成false同步请求，不然就会跳过这里往下执行，这里用匿名函数返回一个数组

最后结果

代码：

 public static T RequestApi<T>(string address)
      {
          string apiUrl = "http://api.map.baidu.com/geocoder/v2/";
          string apiKey = "6Gra1QZ4gWrsrUgirWZ0Z1NdfFrh0mD3"; //
          string output = "json";
        
          IDictionary<string, string> param = new Dictionary<string, string>();
          param.Add("ak", apiKey);
          param.Add("output", output);


          param.Add("address", address);
      
          string result = string.Empty;

          //初始化方案信息实体类。
          T info = default(T);
          try
          {
              //以 Get 形式请求 Api 地址
              result = HttpUtils.DoGet(apiUrl, param);
              info = JsonHelper.FromJson<T>(result);
          }
          catch (Exception)
          {
              info = default(T);
              throw;
          }

          return info;
      }

public class HttpUtils
    {
        /// <summary>
        /// 执行HTTP GET请求。
        /// </summary>
        /// <param name="url">请求地址</param>
        /// <param name="parameters">请求参数</param>
        /// <returns>HTTP响应</returns>
        public static string DoGet(string url, IDictionary<string, string> parameters)
        {
            if (parameters != null && parameters.Count > 0)
            {
                if (url.Contains("?"))
                {
                    url = url + "&" + BuildPostData(parameters);
                }
                else
                {
                    url = url + "?" + BuildPostData(parameters);
                }
            }

            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
            req.ServicePoint.Expect100Continue = false;
            req.Method = "GET";
            req.KeepAlive = true;
            req.UserAgent = "Test";
            req.ContentType = "application/x-www-form-urlencoded;charset=utf-8";

            HttpWebResponse rsp = null;
            try
            {
                rsp = (HttpWebResponse)req.GetResponse();
            }
            catch (WebException webEx)
            {
                if (webEx.Status == WebExceptionStatus.Timeout)
                {
                    rsp = null;
                }
            }

            if (rsp != null)
            {
                if (rsp.CharacterSet != null)
                {
                    Encoding encoding = Encoding.GetEncoding(rsp.CharacterSet);
                    return GetResponseAsString(rsp, encoding);
                }
                else
                {
                    return string.Empty;
                }
            }
            else
            {
                return string.Empty;
            }
        }

        /// <summary>
        /// 把响应流转换为文本。
        /// </summary>
        /// <param name="rsp">响应流对象</param>
        /// <param name="encoding">编码方式</param>
        /// <returns>响应文本</returns>
        private static string GetResponseAsString(HttpWebResponse rsp, Encoding encoding)
        {
            StringBuilder result = new StringBuilder();
            Stream stream = null;
            StreamReader reader = null;

            try
            {
                // 以字符流的方式读取HTTP响应
                stream = rsp.GetResponseStream();
                reader = new StreamReader(stream, encoding);

                // 每次读取不大于256个字符，并写入字符串
                char[] buffer = new char[256];
                int readBytes = 0;
                while ((readBytes = reader.Read(buffer, 0, buffer.Length)) > 0)
                {
                    result.Append(buffer, 0, readBytes);
                }
            }
            catch (WebException webEx)
            {
                if (webEx.Status == WebExceptionStatus.Timeout)
                {
                    result = new StringBuilder();
                }
            }
            finally
            {
                // 释放资源
                if (reader != null) reader.Close();
                if (stream != null) stream.Close();
                if (rsp != null) rsp.Close();
            }

            return result.ToString();
        }

        /// <summary>
        /// 组装普通文本请求参数。
        /// </summary>
        /// <param name="parameters">Key-Value形式请求参数字典。</param>
        /// <returns>URL编码后的请求数据。</returns>
        private static string BuildPostData(IDictionary<string, string> parameters)
        {
            StringBuilder postData = new StringBuilder();
            bool hasParam = false;

            IEnumerator<KeyValuePair<string, string>> dem = parameters.GetEnumerator();
            while (dem.MoveNext())
            {
                string name = dem.Current.Key;
                string value = dem.Current.Value;
                // 忽略参数名或参数值为空的参数
                if (!string.IsNullOrEmpty(name) && !string.IsNullOrEmpty(value))
                {
                    if (hasParam)
                    {
                        postData.Append("&");
                    }

                    postData.Append(name);
                    postData.Append("=");
                    postData.Append(Uri.EscapeDataString(value));
                    hasParam = true;
                }
            }

            return postData.ToString();
        }

    }

public static class JsonHelper
    {
        private static JsonSerializerSettings _jsonSettings;

        static JsonHelper()
        {
            IsoDateTimeConverter datetimeConverter = new IsoDateTimeConverter();
            datetimeConverter.DateTimeFormat = "yyyy-MM-dd HH:mm:ss";

            _jsonSettings = new JsonSerializerSettings();
            _jsonSettings.MissingMemberHandling = Newtonsoft.Json.MissingMemberHandling.Ignore;
            _jsonSettings.NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore;
            _jsonSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
            _jsonSettings.Converters.Add(datetimeConverter);
        }

        /// <summary>
        /// 将指定的对象序列化成 JSON 数据。
        /// </summary>
        /// <param name="obj">要序列化的对象。</param>
        /// <returns></returns>
        public static string ToJson(this object obj)
        {
            try
            {
                if (null == obj)
                    return null;

                return JsonConvert.SerializeObject(obj, Formatting.None, _jsonSettings);
            }
            catch (Exception ex)
            {

                return null;
            }
        }

        /// <summary>
        /// 将指定的 JSON 数据反序列化成指定对象。
        /// </summary>
        /// <typeparam name="T">对象类型。</typeparam>
        /// <param name="json">JSON 数据。</param>
        /// <returns></returns>
        public static T FromJson<T>(this string json)
        {
            try
            {
                return JsonConvert.DeserializeObject<T>(json, _jsonSettings);
            }
            catch (Exception ex)
            {


                return default(T);
            }
        }
    }

最后结果：

 public static IEnumerable<JWCDTO> GetAllJW()
        {
            List<BigDataDTO> p = GetAll().ToList();

            List<JWCDTO> list = new List<JWCDTO>(); ;
            foreach (BigDataDTO pp in p)
            {
                string address = pp.Address;
                int count = pp.count;
                BGDTO bg = Re.RequestApi<BGDTO>(address);
                if(bg==null)
                {
                    continue;
                }
                string lat = bg.result.location.lat;
                string lng = bg.result.location.lng;
                JWCDTO log = ToProductDTO(lat, lng, count);
                list.Add(log);//list.Add(ToLog(row));

            }

            return list;

        }

JW.ashx:

 public class JW : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "application/json";
            List<JWCDTO> p;
            p = ReJson.GetAllJW().ToList();
            context.Response.Write(new JavaScriptSerializer().Serialize(p));
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }

前台页面：

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="ReJson.aspx.cs" Inherits="XZ.UI.Web.Admin.ReJson" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
    <script type="text/javascript" src="http://api.map.baidu.com/api?v=2.0&ak=1fReIR62vFbOc2vgrBnRAGyUtLkgoIIH"></script>
    <script type="text/javascript" src="http://api.map.baidu.com/library/Heatmap/2.0/src/Heatmap_min.js"></script>
    <script src="../Scripts/jquery-1.9.1.min.js" type="text/javascript"></script>

    <title></title>
     <style type="text/css">
        ul,li{list-style: none;margin:0;padding:0;float:left;}
        html{height:100%}
        body{height:100%;margin:0px;padding:0px;font-family:"微软雅黑";}
        #container{height:700px;100%;}
        #r-result{100%;}
    </style>    
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <div id="container"></div>
        <div id="r-result">
            <input type="button"  onclick="openHeatmap();" value="显示热力图"/><input type="button"  onclick="closeHeatmap();" value="关闭热力图"/>
        </div>
    </div>
    </form>
</body>
</html>

<script type="text/javascript">
    var map = new BMap.Map("container");          // 创建地图实例

    var point = new BMap.Point(118.906886, 31.895532);
    map.centerAndZoom(point, 15);             // 初始化地图，设置中心点坐标和地图级别
    map.enableScrollWheelZoom(); // 允许滚轮缩放
 
    if (!isSupportCanvas()) {
        alert('热力图目前只支持有canvas支持的浏览器,您所使用的浏览器不能使用热力图功能~')
    }
 
    heatmapOverlay = new BMapLib.HeatmapOverlay({ "radius": 20 });
    map.addOverlay(heatmapOverlay);
    heatmapOverlay.setDataSet({ data: function () {
        var serie = [];
        $.ajax({
            url: "JW.ashx",
            dataType: "json",
            async: false,
            success: function (dataJson) {
                for (var i = 0; i < dataJson.length; i++) {
                    var item = {
                        lat: dataJson[i].lat,
                        lng: dataJson[i].lng,
                        count: dataJson[i].count
                    };
                    serie.push(item);
                }
            }
        });
        return serie;
    } (), max: 100 });
    //是否显示热力图
    function openHeatmap() {
        heatmapOverlay.show();
    }
    function closeHeatmap() {
        heatmapOverlay.hide();
    }
    closeHeatmap();
    function setGradient() {
        /*格式如下所示:
        {
        0:'rgb(102, 255, 0)',
        .5:'rgb(255, 170, 0)',
        1:'rgb(255, 0, 0)'
        }*/
        var gradient = {};
        var colors = document.querySelectorAll("input[type='color']");
        colors = [].slice.call(colors, 0);
        colors.forEach(function (ele) {
            gradient[ele.getAttribute("data-key")] = ele.value;
        });
        heatmapOverlay.setOptions({ "gradient": gradient });
    }
    //判断浏览区是否支持canvas
    function isSupportCanvas() {
        var elem = document.createElement('canvas');
        return !!(elem.getContext && elem.getContext('2d'));
    }
</script>