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 > )
             {
                 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[];
                 int readBytes = ;
                 while ((readBytes = reader.Read(buffer, , buffer.Length)) > )
                 {
                     result.Append(buffer, , 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;width:100%;}
         #r-result{width: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>