高德地图上绘制热力图的方法

百度地图和高德地图的JavaScript API都提供了热力图的绘制方法，都是将热力图作为新的图层，叠加到地图上。但是百度地图的经纬度体系与我们的经纬度存在偏差，高德的与我们相符，应当使用高德地图JavaScript API。

因为是JavaScript API，所以地图展示是在网页上的。以高德地图的API使用为例：

在html文件中添加高德地图必须的script，其中第一行的key可以在高德官网免费申请。

准备-入门-教程-地图 JS API 1.4 | 高德地图API准备本章向您介绍使用高德地图JSAPI开发应用之前的一些准备工作。注册账号并申请Key1.首先，注册开发者账号，成为高德https://lbs.amap.com/api/javascript-api/guide/abc/prepare

https://lbs.amap.com/api/javascript-api/guide/abc/prepare

html源码如下：

<!doctype html>
<html>
<head><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="initial-scale=1.0, user-scalable=no, width=device-width"><title>热力图</title><link rel="stylesheet" href="http://cache.amap.com/lbs/static/main1119.css"/><script src="http://webapi.amap.com/maps?v=1.3&key=	898eb9*******************"></script><script type="text/javascript" src="http://cache.amap.com/lbs/static/addToolbar.js"></script><script type="text/javascript" src="http://a.amap.com/jsapi_demos/static/resource/heatmapData.js"></script>
</head>
<body>
<div id="container"></div>
<div class="button-group"><input type="button" class="button" value="显示热力图" οnclick="heatmap.show()"/><input type="button" class="button" value="关闭热力图" οnclick="heatmap.hide()"/>
</div>
<script>var map = new AMap.Map("container", {resizeEnable:false,center: [121.196087,31.05471],   //华政经纬度zoom: 11});if (!isSupportCanvas()) {alert('热力图仅对支持canvas的浏览器适用,您所使用的浏览器不能使用热力图功能,请换个浏览器试试~')}var points =[
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{"lat":31.994129,"lng":121.454422,"count":1}];//详细的参数,可以查看heatmap.js的文档 http://www.patrick-wied.at/static/heatmapjs/docs.html//参数说明如下:/* visible 热力图是否显示,默认为true* opacity 热力图的透明度,分别对应heatmap.js的minOpacity和maxOpacity* radius 势力图的每个点的半径大小   * gradient  {JSON} 热力图的渐变区间 . gradient如下所示* {.2:'rgb(0, 255, 255)',.5:'rgb(0, 110, 255)',.8:'rgb(100, 0, 255)'}其中 key 表示插值的位置, 0-1 value 为颜色值 */var heatmap;map.plugin(["AMap.Heatmap"], function() {//初始化heatmap对象heatmap = new AMap.Heatmap(map, {radius: 15, //给定半径opacity: [0, 0.8]/*,gradient:{0.5: 'blue',0.65: 'rgb(121,211,248)',0.7: 'rgb(0, 255, 0)',0.9: '#ffea00',1.0: 'red'}*/});//设置数据集heatmap.setDataSet({data: points,max: 5});});//判断浏览区是否支持canvasfunction isSupportCanvas() {var elem = document.createElement('canvas');return !!(elem.getContext && elem.getContext('2d'));}
</script>
</body>
</html>