在ArcGIS Viewer for Flex开发中，经常需要用到google map作为底图，我们不能通过ArcGIS Viewer for Flex – Application Builder轻易的引入google map 作为底图，需要通过程序重写TiledMapServiceLayer来扩展从而加载google map。
这里有写好的GoogleMapLayer.as文件：
package com.esri.viewer { import com.esri.ags.SpatialReference; import com.esri.ags.geometry.Extent; import com.esri.ags.geometry.MapPoint; import com.esri.ags.layers.TiledMapServiceLayer; import com.esri.ags.layers.supportClasses.LOD; import com.esri.ags.layers.supportClasses.TileInfo; import flash.net.URLRequest; //扩展TiledMapServiceLayer图层实现加载google地图 public class GoogleMapLayer extends TiledMapServiceLayer { private var _tileInfo:TileInfo=new TileInfo(); private var _baseURL:String=""; public var mapStyle:String=""; public function GoogleMapLayer() { super(); buildTileInfo(); setLoaded(true); } override public function get fullExtent():Extent { return new Extent(-20037508.342787, -20037508.342787, 20037508.342787, 20037508.342787, new SpatialReference(102113)); } override public function get initialExtent():Extent { return new Extent(-20037508.342787, -20037508.342787, 20037508.342787, 20037508.342787, new SpatialReference(102113)); } override public function get spatialReference():SpatialReference { return new SpatialReference(102113); } override public function get tileInfo():TileInfo { return _tileInfo; } //获取矢量地图 override protected function getTileURL(level:Number, row:Number, col:Number):URLRequest { var s:String = "Galileo".substring(0, ((3 * x + y) % 8)); var url:String; //获取矢量地图 if(mapStyle == "Vector") { url = "http://mt"+(col%4)+".google.com/vt/lyrs=m@158000000&hl=zh-CN&gl=cn&" + "x=" + col + "&" + "y=" + row + "&" + "z=" + level+ "&" + "s=" + s; } //获取地形图 else if(mapStyle == "Terrain") { url = "http://mt"+(col%4)+".google.cn/vt/lyrs=t@131,r@227000000&hl=zh-CN&gl=cn&" + "x=" + col + "&" + "y=" + row + "&" + "z=" + level+ "&" + "s=" + s; } //获取影像地图 else if(mapStyle == "Image") { url = "http://mt"+(col%4)+".google.com/vt/lyrs=s&hl=en&gl=en&" + "x=" + col + "&" + "y=" + row + "&" + "z=" + level+ "&" + "s=" + s; } //获取道路等POI，和影像地图配合使用 else if(mapStyle == "POI") { url = "http://mt"+(col%4)+".google.com/vt/imgtp=png32&lyrs=h@169000000&hl=zh-CN&gl=cn&" + "x=" + col + "&" + "y=" + row + "&" + "z=" + level+ "&" + "s=" + s; } return new URLRequest(url); } private function buildTileInfo():void { _tileInfo.height=256; _tileInfo.width=256; _tileInfo.origin=new MapPoint(-20037508.342787, 20037508.342787); _tileInfo.spatialReference=new SpatialReference(102113); _tileInfo.lods = [ new LOD(0, 156543.033928, 591657527.591555), new LOD(1, 78271.5169639999, 295828763.795777), new LOD(2, 39135.7584820001, 147914381.897889), new LOD(3, 19567.8792409999, 73957190.948944), new LOD(4, 9783.93962049996, 36978595.474472), new LOD(5, 4891.96981024998, 18489297.737236), new LOD(6, 2445.98490512499, 9244648.868618), new LOD(7, 1222.99245256249, 4622324.434309), new LOD(8, 611.49622628138, 2311162.217155), new LOD(9, 305.748113140558, 1155581.108577), new LOD(10, 152.874056570411, 577790.554289), new LOD(11, 76.4370282850732, 288895.277144), new LOD(12, 38.2185141425366, 144447.638572), new LOD(13, 19.1092570712683, 72223.819286), new LOD(14, 9.55462853563415, 36111.909643), new LOD(15, 4.77731426794937, 18055.954822), new LOD(16, 2.38865713397468, 9027.977411), new LOD(17, 1.19432856685505, 4513.988705), new LOD(18, 0.597164283559817, 2256.994353), new LOD(19, 0.298582141647617, 1128.497176) ]; } } }
具体步骤如下：
第一步：将文件GoogleMapLayer.as放到com.esri.viewer包下
第二步：在MapManager.mxml文件中：
（1）引入包com.esri.viewer.GoogleMapLayer。
（2）在addLayerToMap函数中添加：
第三步：在LayerCreator.as文件中：
（1）引入包com.esri.viewer.GoogleMapLayer：
（2）在createLayer函数中添加：
else if (layerType == "googlemap") { return createGoogleLayer(layerCreationProperties); }
（3）添加函数createGoogleLayer：
private static function createGoogleLayer(layerCreationProperties:LayerCreationProperties):GoogleMapLayer { var googleLayer:GoogleMapLayer=new GoogleMapLayer(); googleLayer.name=layerCreationProperties.label; if (layerCreationProperties.style) { googleLayer.mapStyle= layerCreationProperties.style; } googleLayer.id=layerCreationProperties.label; googleLayer.alpha=layerCreationProperties.alpha; googleLayer.visible=layerCreationProperties.visible; return googleLayer; }
第四步：在config.xml配置文件中添加basemaps：
<basemaps>
<layer label="GoogleMapLayer" type="GoogleMap" icon="assets/images/birds.png" style="Terrain" visible="true"/>
</basemaps>
运行结果：
