0.引言
ArcGIS API for JavaScript是一款由Esri公司开发的用于创建WebGIS应用的JavaScript库。它允许开发者通过调用ArcGIS Server的REST API，将地图资源和其它资源（如ArcGIS Online）嵌入到Web应用中。ArcGIS API for JavaScript提供了丰富的功能，包括页面布局、地图图层、空间坐标转换、要素符号、专题图、属性查询、空间分析、三维场景、小部件、渲染器等。本文介绍如何快速入门ArcgisForJs。
1.前端代码编辑工具
（1）ArcgisForJs沙盒
ArcgisForJs的代码编写和测试在沙盒中进行。
ArcgisForJs沙盒可以访问： https://developers.arcgis.com/javascript/3/sandbox/sandbox.html?sample=map_create
（2）代码笔
CodePen（代码笔）一款前端所见即所得的工具，我们可以在线编辑制作前端页面，所见即所得。同时网站提供所有常见的 js、css 库，并且支持流行技术（如 SASS），免去了我们自建平台的麻烦。编辑器网址： https://codepen.io/pen/
2.使用ArcgisForJs创建一个简单应用
创建任何GIS地图应用程序，都需要遵循一些步骤。假如想让地图成为应用程序的一部分，那么就需要按照这些步骤来执行。需要遵循以下步骤：①创建页面HTML代码；②引用ArcGIS API for JavaScript和样式表；③加载模块；④确保DOM可用；⑤创建地图；⑥定义页面内容；⑦页面样式。
（1）主要代码
<!DOCTYPE html>
<html>
<head>
<title>Create a Map</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
<link rel="stylesheet" href="https://js.arcgis.com/3.45/dijit/themes/claro/claro.css">
<link rel="stylesheet" href="https://js.arcgis.com/3.45/esri/css/esri.css">
<style>
html, body, #mapDiv {
padding: 0;
margin: 0;
height: 100%;
}
</style>
<script src="https://js.arcgis.com/3.45/"></script>
<script>
dojo.require("esri.map");
function init(){
var map = new esri.Map("mapDiv", {
basemap: "topo-vector",
center: [-122.45, 37.75],
zoom: 13
});
}
dojo.ready(init);
</script>
</head>
<body class="claro">
<div id="mapDiv"></div>
</body>
</html>
（2）结果显示
3.切片地图服务图层
ArcGISTiledMapServiceLayer类使用在当引用ArcGIS Server暴露的切片（缓存）地图服务时。这种类型的对象使用已经缓存过的切片地图集合，所以性能得以改善。
（1）主要代码
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="initial-scale=1, maximum-scale=1, user-scalable=no">
<title>Tiled map service</title>
<link rel="stylesheet" href="https://js.arcgis.com/3.45/esri/css/esri.css">
<style>
html, body, #map {
height: 100%; width: 100%; margin: 0; padding: 0;
}
</style>
<script src="https://js.arcgis.com/3.45/"></script>
<script>
var map;
require(["esri/map",
"esri/layers/ArcGISTiledMapServiceLayer",
"esri/geometry/Point",
"esri/SpatialReference",
"dojo/domReady!"],
function(Map, ArcGISTiledMapServiceLayer, Point, SpatialReference) {
map = new Map("map", {
center: new Point(1714791.187457787, 2194882.166227445, new SpatialReference({ wkid: 5936 }))
});
var tiled = new ArcGISTiledMapServiceLayer("https://services.arcgisonline.com/arcgis/rest/services/Polar/Arctic_Imagery/MapServer");
map.addLayer(tiled);
}
);
</script>
</head>
<body>
<div id="map"></div>
</body>
</html>
（2）结果显示
4.动态地图服务图层
ArcGISDynamicMapService类用来动态创建ArcGIS Server地图服务。
（1）主要代码
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
<title>Create Map and add a dynamic layer</title>
<link rel="stylesheet" href="https://js.arcgis.com/3.45/esri/css/esri.css"/>
<style>
html, body, #mapDiv{
padding: 0;
margin: 0;
height: 100%;
}
</style>
<script src="https://js.arcgis.com/3.45/"></script>
<script>
var map;
require([
"esri/map",
"esri/layers/ArcGISDynamicMapServiceLayer",
"esri/layers/ImageParameters"
], function (
Map, ArcGISDynamicMapServiceLayer, ImageParameters) {
map = new Map("mapDiv", {
sliderOrientation : "horizontal"
});
var imageParameters = new ImageParameters();
imageParameters.format = "jpeg"; // default is PNG8.
//Takes a URL to a non cached map service.
var dynamicMapServiceLayer = new ArcGISDynamicMapServiceLayer("https://sampleserver6.arcgisonline.com/arcgis/rest/services/SampleWorldCities/MapServer", {
"imageParameters" : imageParameters
});
map.addLayer(dynamicMapServiceLayer);
});
</script>
</head>
<body>
<div id="mapDiv"></div>
</body>
</html>
（2）结果显示
5.地图事件
在编程世界里，事件是发生在应用程序中的动作。通常，这些事件通过终端用户触发，包括鼠标单击、鼠标拖拽和键盘动作，但是它还包括数据的发送和接收、组件修改和其他操作。
（1）主要代码
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no">
<title>Select with feature layer</title>
<link rel="stylesheet" href="https://js.arcgis.com/3.45/dijit/themes/tundra/tundra.css">
<link rel="stylesheet" href="https://js.arcgis.com/3.45/esri/css/esri.css">
<style>
html, body, #mapDiv {
padding: 0;
margin: 0;
height: 100%;
}
#messages{
background-color: #fff;
box-shadow: 0 0 5px #888;
font-size: 1.1em;
max-width: 15em;
padding: 0.5em;
position: absolute;
right: 20px;
top: 20px;
z-index: 40;
}
</style>
<script src="https://js.arcgis.com/3.45/"></script>
<script>
var map;
require([
"esri/map", "esri/layers/FeatureLayer",
"esri/tasks/query", "esri/geometry/Circle",
"esri/graphic", "esri/symbols/SimpleMarkerSymbol",
"esri/symbols/SimpleLineSymbol", "esri/symbols/SimpleFillSymbol", "esri/renderers/SimpleRenderer",
"esri/config", "esri/Color", "dojo/dom", "dojo/domReady!"
], function(
Map, FeatureLayer,
Query, Circle,
Graphic, SimpleMarkerSymbol,
SimpleLineSymbol, SimpleFillSymbol, SimpleRenderer,
esriConfig, Color, dom
) {
map = new Map("mapDiv", {
basemap: "streets-vector",
center: [-95.249, 38.954],
zoom: 14,
slider: false
});
// Add the census block points in on demand mode. An outfield is specified since it is used when calculating the total population falling within the one mile radius.
var featureLayer = new FeatureLayer("https://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/0",{
outFields: ["POP2000"]
});
// Selection symbol used to draw the selected census block points within the buffer polygon
var symbol = new SimpleMarkerSymbol(
SimpleMarkerSymbol.STYLE_CIRCLE,
12,
new SimpleLineSymbol(
SimpleLineSymbol.STYLE_NULL,
new Color([247, 34, 101, 0.9]),
1
),
new Color([207, 34, 171, 0.5])
);
featureLayer.setSelectionSymbol(symbol);
// Make unselected features invisible
var nullSymbol = new SimpleMarkerSymbol().setSize(0);
featureLayer.setRenderer(new SimpleRenderer(nullSymbol));
map.addLayer(featureLayer);
var circleSymb = new SimpleFillSymbol(
SimpleFillSymbol.STYLE_NULL,
new SimpleLineSymbol(
SimpleLineSymbol.STYLE_SHORTDASHDOTDOT,
new Color([105, 105, 105]),
2
), new Color([255, 255, 0, 0.25])
);
var circle;
// When the map is clicked create a buffer around the click point of the specified distance
map.on("click", function(evt){
circle = new Circle({
center: evt.mapPoint,
geodesic: true,
radius: 1,
radiusUnit: "esriMiles"
});
map.graphics.clear();
var graphic = new Graphic(circle, circleSymb);
map.graphics.add(graphic);
var query = new Query();
query.geometry = circle.getExtent();
// Use a fast bounding box query. It will only go to the server if bounding box is outside of the visible map.
featureLayer.queryFeatures(query, selectInBuffer);
});
function selectInBuffer(response){
var feature;
var features = response.features;
var inBuffer = [];
// Filter out features that are not actually in buffer, since we got all points in the buffer's bounding box
for (var i = 0; i < features.length; i++) {
feature = features[i];
if(circle.contains(feature.geometry)){
inBuffer.push(feature.attributes[featureLayer.objectIdField]);
}
}
var query = new Query();
query.objectIds = inBuffer;
// Use an objectIds selection query (should not need to go to the server)
featureLayer.selectFeatures(query, FeatureLayer.SELECTION_NEW, function(results){
var totalPopulation = sumPopulation(results);
var r = "";
r = "<b>The total Census Block population within the buffer is <i>" + totalPopulation + "</i>.</b>";
dom.byId("messages").innerHTML = r;
});
}
function sumPopulation(features) {
var popTotal = 0;
for (var x = 0; x < features.length; x++) {
popTotal = popTotal + features[x].attributes["POP2000"];
}
return popTotal;
}
});
</script>
</head>
<body>
<span id="messages">Click on the map to select census block points within 1 mile.</span>
<div id="mapDiv"></div>
</body>
</html>
（2）结果显示
参考资料：
[1] 派普勒[著]张大伟[译]. 《JavaScript构建Web和ArcGIS Server应用实战》; 2015-12-01 [accessed 2024-01-28].
[2] hangge. CodePen - 一个在线的前端代码编辑工具（可用于制作测试页面、代码调试）; 2019-12-02 [accessed 2024-01-28].
[3] . ArcGIS Maps SDK for JavaScript; [accessed 2024-01-28].
[4] . ArcGIS API for JavaScript (legacy) 3.45; [accessed 2024-01-28].
[5] 祥哥哥咩~. arcgis for js图层graphic的鼠标悬浮事件; 2019-04-26 [accessed 2024-01-28].