ArcGIS api for javascript——动态创建图层列表

描述

本例循环地图服务里的所有图层并增加每个图层到一个带checkbox的列表，checkbox能设置图层的显示或隐藏。动态创建列表的优势是所有的图层都会包含在列表中，即使服务器管理员删除或增加了图层。如果不想包含所有图层，仅仅要一个子集，见示例 Explicitly create layer list。

注意本例在建立图层列表以前检查图层是否被完全加载。

函数buildLayerList()循环访问每个图层并作为一个HTML checkbox加入列表。该函数建立了一个图层列表。默认每个图层的可见行被保存在列表中。

每当某人选择或不选checkbox，函数updateLayerVisibility()被调用。函数循环访问列表中的每个图层，记录哪些图层是可见的数组，然后调用 ArcGISDynamicMapServiceLayer.setVisibleLayers()方法。地图服务里的地图数组可以通过这个方法被设置。

 1 <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
 2 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
 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     <title>动态创建图层列表</title>
 8     <link rel="stylesheet" type="text/css" href="http://serverapi.arcgisonline.com/jsapi/arcgis/1.6/js/dojo/dijit/themes/tundra/tundra.css">
 9     <script type="text/javascript" src="http://serverapi.arcgisonline.com/jsapi/arcgis/?v=1.6"></script>
10     <script type="text/javascript">
11         dojo.require("esri.map");
12         
13         var dynamicMapServiceLayer,map,visible = [];
14         
15         function init() {
16             map = new esri.Map("map");
17             
18             dynamicMapServiceLayer = new esri.layers.ArcGISDynamicMapServiceLayer(
19                 "http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Specialty/ESRI_StatesCitiesRivers_USA/MapServer"
20             );
21             
22             if (dynamicMapServiceLayer.loaded) {        
23                 buildLayerList(dynamicMapServiceLayer);              
24             }else{
25                 dojo.connect(dynamicMapServiceLayer,"onLoad",buildLayerList);
26             }       
27         }
28         
29         function buildLayerList(layer) {
30             var infos = layer.layerInfos, info;
31             var items = [];
32             for (var i=0,j=infos.length;i<j;i++) {
33                 info = infos[i];
34                 if (info.defaultVisibility) {
35                     visible.push(info.id);
36                 }
37                 items[i] = "<input type='checkbox' class='list_item' checked='" + (info.defaultVisibility ? "checked" : "") + "' id='" + info.id +"' onclick='updateLayerVisibility();'/><label for='" +info.id+ "'>" +info.name+ "</label>";          
38             }
39             dojo.byId("layer_list").innerHTML = items.join();
40             
41             layer.setVisibleLayers(visible);
42             map.addLayer(layer);
43         
44         }
45         
46         function updateLayerVisibility() {
47             var inputs = dojo.query(".list_item"), input;
48             visible = [];
49             for (var i=0,j=inputs.length;i<j;i++) {
50                 if(inputs[i].checked) {
51                     visible.push(inputs[i].id);
52                 }           
53             }
54             dynamicMapServiceLayer.setVisibleLayers(visible);
55         
56         }
57         dojo.addOnLoad(init);
58     
59     </script>
60 
61   </head>
62 
63   <body >
64       This sample loads an ArcGISDynamicMapServiceLayer.<br />
65     It determines the layers in the map service and presents them as checkboxes that can be used to toggle their visibility.<br />
66     <br />
67       Layer List: <span id="layer_list"></span><br />
68       <br />
69       <div id="map" class="tundra" style=" 900px;height: 600px;border: 1px solid #000"></div>
70   </body>
71 </html>