ArcGIS api for javascript——用第二个服务的范围设置地图范围

描述

本例展示了如何设置地图的范围为地图其中一个图层的范围。本例有两个图层：ArcGIS Online上的世界地图图层 ArcGISTiledMapServiceLayer和堪萨斯州的要素的图层ArcGISDynamicMapServiceLayer。本例展示了如何设置地图总是以堪萨斯州范围开始。

代码包含两个事件监听器，一个是为了每个图层。这些监听器帮助记录多少图层被加载。当图层计数是2，createMapAddLayers函数被调用。这个函数创建一个地图，设置地图范围是myService2（堪萨斯州服务）的范围：

myMap = new esri.Map("mapDiv", { extent:myService2.fullExtent });

地图被创建以后，图层被增加。注意加载图层和增加图层不是一回事。在本例中，地图被创建前图层加载，地图创建以后图层被加到地图里。

直到所有图层被加载前要避免访问地图属性。如果代码中没有包含事件监听器，有可能在myService2完全加载前地图就会尝试去设置它的范围，这回引起意想不到的结果。

 1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
 2 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 3 <html>
 4   <head>
 5     <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
 6     <meta http-equiv="X-UA-Compatible" content="IE=7" />
 7     
 8     <title>Set Map Extent Using Second Service</title>
 9     
10     <link rel="stylesheet" type="text/css" href="styles.css"
11           href="http://serverapi.arcgisonline.com/jsapi/arcgis/1.6/js/dojo/dijit/themes/tundra/tundra.css">
12     <script type="text/javascript" src="http://serverapi.arcgisonline.com/jsapi/arcgis/?v=1.6"></script>
13     <script type="text/javascript">
14         dojo.require("esri.map");
15         var map,myservice1,myservice2;
16         
17         function init(){
18             map=new esri.Map("map");
19              myService1=new esri.layers.ArcGISTiledMapServiceLayer(
20             "http://server.arcgisonline.com/ArcGIS/rest/services/ESRI_StreetMap_World_2D/MapServer"
21           // "http://server.arcgisonline.com/ArcGIS/rest/services/ESRI_Imagery_World_2D/MapServer"
22             );
23              
24             var secondaryMapServiceURL = "http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Petroleum/KGS_OilGasFields_Kansas/MapServer";
25             //var secondaryMapServiceURL = "http://118.144.36.6:6080/arcgis/rest/services/chakan/henan530/MapServer";
26             myService2 = new esri.layers.ArcGISDynamicMapServiceLayer(secondaryMapServiceURL,{opacity:0.65});
27             
28             var layerLoadCount=0;
29             //当两个图层加载时运行creatMapAddLayers
30             
31             if(myService1.loded){
32                 layerLoadCount+=1;
33                 if(layerLoadCount == 2){
34                     creatMapAddLayers(myService1,myService2);
35                 }
36             }else{
37                 dojo.connect(myservice1,"onLoad",function(service){
38                     layerLoadCount += 1;
39                     if(layerLoadCount == 2){
40                         creatMapAddLayers(myService1,myService2);
41                     }            
42                 });
43             }
44             if(myService2.loded){
45                 layerLoadCount+=1;
46                 if(layerLoadCount == 2){
47                     creatMapAddLayers(myService1,myService2);
48                 }
49             
50             }else{
51                 dojo.connect(myservice2,"onLoad",function(service){
52                     layerLoadCount += 1;
53                     if(layerLoadCount == 2){
54                         creatMapAddLayers(myService1,myService2);
55                     }
56             
57             });            
58         }
59         //创建一个地图，设置范围并添加到地图服务中
60         function creatMapAddLayers(myService1,myService2){
61         //创建地图
62             map=new esri.Map("mapDiv",{extent:myservice2.fullExtent});
63             map.addLayer(myService1);
64             map.addLayer(myService2);
65             dojo.connect(map,"onClick",addPoint);
66             function addPoint(event){
67                 map.infoWindow.setTitle("Coordinates-坐标");
68                 map.infoWindow.setContent("经/纬：" + event.mapPoint.x + "," + event.mapPoint.y
69                 +"<br/>screen x/y: " + event.screenPoint.x + ","+event.screenPoint.y);
70                 
71                 map.infoWindow.show(event.screenPoint,map.getInfoWindowAnchor(event.screenPoint));
72             }
73         
74         }
75         
76         
77         }
78         dojo.addOnLoad(init);
79         
80     </script>
81   </head>
82   
83   <body class="tundra">
84     <div id="map" style="600px;height:400px;border:1px solid #000"></div>
85     <br>
86     This map shows two services:
87     <ul>
88     <li>An ArcGIS Online tiled service that has a world extent.</li>
89     <li>A second dynamic service with an extent of the State of Kansas.  This is the extent used when the maps are first displayed. </li>
90     </ul>
91 
92     Note that if you want to combine to tiled services in the same map, they must have the same tile configuration.
93   </body>
94 </html>