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="width: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>
