ArcGIS.Server.9.3和ArcGIS API for Flex的GeometryService和buffer分析

1.ArcGIS API for Flex用GeometryService实现点、线、面的buffer分析。
准备工作：
1.在ArcGIS.Server.9.3发布一个叫USA的Map Service。
2.在ArcGIS.Server.9.3发布一个叫Geometry的Geometry Service，默认设置就可以了。
完成后的效果图：

开始：
0.首先介绍一下Geometry Service，Geometry Service是给程序提供几何计算如 buffering, simplifying, calculating areas 、lengths,  projecting等功能，Geometry Service可以用来代替ArcObjects 或geoprocessing service等做的这些几何计算，它是ArcGIS Server 9.3提供的新功能，本篇就是用它来实现buffer的分析。
1.启动Flex Builder3新建工程以及引入1.0正式版的ArcGIS API for Flex library的开发包。
2.新建bufferTest.mxml页面，添加Map、ArcGISDynamicMapServiceLayer、GraphicsLayer等。具体代码如下： 1<mx:Canvas width="490" height="401" borderStyle="solid" borderThickness="3" verticalCenter="16" left="10">
2    <esri:Map id="myMap" crosshairVisible="true">
3        <esri:ArcGISDynamicMapServiceLayer url="http://jh-53a435fbc0e8/ArcGIS/rest/services/USA/MapServer" />
4        <esri:GraphicsLayer id="myGraphicsLayer"  />
5    </esri:Map>
6    </mx:Canvas>3. 然后在Map控件的右边在添加一个Grid用来显示buffer分析后的数据，代码如下： 1<mx:DataGrid id="datalist" height="398" verticalCenter="14" borderStyle="solid" borderThickness="3" left="508">
2    </mx:DataGrid>4.这里既然是用Geometry Service实现buffer的当然还需要添加esri:GeometryService控件，它的url属性就是上面发布的叫Geometry的Geometry Service的地址，代码如下： 1<esri:GeometryService id="myGeometryService" url="http://jh-53a435fbc0e8/ArcGIS/rest/services/Geometry/GeometryServer"/>5.这里采用在地图上画点、线、面然后根据画的几何图进行buffer,所以还需要ToggleButtonBar按钮组控件、Draw控件以及图形显示样式的定义，具体代码如下：  1<esri:SimpleFillSymbol id="sfs" color="0xFF0000" alpha="0.6">
2    </esri:SimpleFillSymbol>
3    <esri:Draw id="drawToolbar" map="{myMap}" graphicsLayer="{myGraphicsLayer}" drawEnd="drawEndHandler(event)" />
4    <mx:ToggleButtonBar verticalCenter="-203"  itemClick="itemClickHandler(event)" toggleOnClick="true" left="11">
5        <mx:dataProvider>
6        <mx:Array>
7        <mx:Object icon="{point}" />
8        <mx:Object icon="{polyline}" />
9        <mx:Object icon="{polygon}" />
10        </mx:Array>
11        </mx:dataProvider>
12    </mx:ToggleButtonBar>6.point、polyline、polygon的icon定义如下：  1<mx:Script>
2        <![CDATA[
3                  
4        [Bindable]
5            [Embed(source="assets/point.gif")]
6            public var point:Class;
7
8            [Bindable]
9            [Embed(source="assets/polyline.gif")]
10            public var polyline:Class;
11
12            [Bindable]
13            [Embed(source="assets/polygon.gif")]
14            public var polygon:Class;
15                   
16            ]]>
17    </mx:Script>7.进行buffer后得到的图形然后用来查询相关结果了所以还需要添加IdentifyTask控件，代码如下： 1<esri:IdentifyTask id="identifyTask" identifyComplete="identifyCompleteHandler(event)" url="http://jh-53a435fbc0e8/ArcGIS/rest/services/USA/MapServer"/>8.接下来开始编写功能代码，过程首先是用Draw工具在GraphicsLayer上画几何图形，然后用GeometryService对几何图形进行buffer，然后用分析得到的结果图形进行IdentifyTask出结果显示在DataGrid中。
9.按照上面的过程首先添加ToggleButtonBar的itemClick事件方法itemClickHandler(event)，代码如下：  1private function itemClickHandler(event:ItemClickEvent):void
2            {
3                switch(event.index)
4                {
5                    case 0:
6                    {
7                        drawToolbar.activate(Draw.MAPPOINT);
8                        break;
9                    }
10                    case 1:
11                    {
12                        drawToolbar.activate(Draw.POLYLINE);
13                        break;
14                    }
15                    case 2:
16                    {
17                        drawToolbar.activate(Draw.POLYGON);
18                        break;
19                    }
20                }
21            }10.接着是Draw控件的drawEnd时间方法drawEndHandler(event)，代码如下：  1private function drawEndHandler(event:DrawEvent):void
2            {
3                var myGraphic:Graphic=event.graphic;
4                //设置buffer参数
5                var bufferParameters : BufferParameters = new BufferParameters();
6                bufferParameters.features=[myGraphic];
7                //buffer距离半径
8                bufferParameters.distances = [100000];
9                //buffer单位
10                bufferParameters.unit = BufferParameters.UNIT_METER;
11                //buffer空间参照系,102113为WKID是REST API定义好的空间参照系的id
12                bufferParameters.bufferSpatialReference = new SpatialReference(102113);                         
13                //添加BUFFER_COMPLETE监听
14                myGeometryService.addEventListener(GeometryServiceEvent.BUFFER_COMPLETE, bufferCompleteHandler); 
15                //进行buffer分析
16                myGeometryService.buffer( bufferParameters );
17            }11.上面的代码中用GeometryService进行buffer已经有详细注释了,执行buffer方法后会执行bufferCompleteHandler方法，代码如下：  1//buffer完成后调用方法
2            private function bufferCompleteHandler( event : GeometryServiceEvent ) : void
3            {
4                myGraphicsLayer.clear();
5                //移除BUFFER_COMPLETE监听
6                myGeometryService.removeEventListener(GeometryServiceEvent.BUFFER_COMPLETE,bufferCompleteHandler);
7                //获取buffer结果Graphic
8                for each (var graphic : Graphic in event.graphics )
9                {
10                    //设置显示样式
11                    graphic.symbol = sfs;
12                    //添加到GraphicsLayer进行显示
13                    myGraphicsLayer.add( graphic );
14                   
15                    var identifyParams:IdentifyParameters=new IdentifyParameters();
16                    //查询结果需要返回Geometry
17                    identifyParams.returnGeometry=true;
18                    //查询冗余范围
19                    identifyParams.tolerance=1;
20                    //宽
21                    identifyParams.width = myMap.width;
22                    //高
23                    identifyParams.height = myMap.height;
24                    //设置查询的Geometry
25                    identifyParams.geometry=graphic.geometry;
26                    //从ComboBox获取选择的图层index设置要查询的图层
27                    //查询图层id为2的图层，就是States层
28                    identifyParams.layerIds=[2];
29                    //查询可见图层
30                    //identifyParams.layerOption=IdentifyParameters.LAYER_OPTION_VISIBLE;
31                    identifyParams.mapExtent=myMap.extent;
32                    //进行查询
33                    identifyTask.execute(identifyParams);
34                }
35            }12.上面的代码中在最后执行了IdentifyTask的execute方法进行Identify查询，查询结束后会调用identifyCompleteHandler方法把结果显示在DataGrid中，代码如下：  1//查询完成后执行的事件
2            private function identifyCompleteHandler(event:IdentifyEvent):void
3            {
4                myNav.activate(Navigation.PAN);
5                var datas:Array=new Array();
6                //myGraphicsLayer.clear();
7                //遍历查询结果把查询到的feature添加到GraphicsLayer进行高亮显示
8                //同时把查询到的元素的名称添加到datas对象数组用来DataGrid显示用
9                for each (var result:IdentifyResult in event.identifyResults)
10                {
11                    myGraphicsLayer.add(result.feature);
12                    //datas.push(result.feature.attributes);   
13                    datas.push({"value":result.value});
14                }
15                //设置mx:DataGrid的数据源
16                datalist.dataProvider=datas;
17            }13.这样就完成了buffer的功能，运行测试效果。