天津政府应急系统之GIS一张图（arcgis api for flex）讲解（九）地图定位模块

config.xml文件的配置如下：

        <widget label="地图定位" config="widgets/esri/Location/LocationWidget.xml" 
            icon="assets/images/ditudingwei.png" url="widgets/esri/Location/LocationWidget.swf" />

源代码目录如下：

界面效果：

大概的思路如下：定位有两种方式：1.后台数据库关联的，即是从后台数据库读取事故列表的定位数据，然后加载出来显示在地图上；2.直接在地图上点击某处，获取该处的定位点信息。两者的共同点都是根据经纬度来定位。

LocationWidget.xml：配置数据库事故列表的字段信息

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<!--    <icon>assets/images/i_target.png</icon>-->
    <icon>assets/images/Red_glow.swf</icon>
    <title>{name}</title>
    <fields>         
        <field name="type" alias="事件类别" visible="true" />
        <field name="event_level_display" alias="事件级别" visible="true" />
        <field name="event_level" alias="事件级别Id" visible="false" />
        <field name="event_time" alias="事发时间" visible="true" />
        <field name="event_man" alias="联系人" visible="true" />
        <field name="event_status" alias="状态" visible="false" />
        <field name="event_status_display" alias="状态" visible="true" />
    </fields>
</configuration>

LocationWidget.mxml:这里截取核心实现部分

        protected function list1_clickHandler(event:ListEvent):void
            { 
                graphicsLayer.clear();
                // TODO Auto-generated method stub
                var graphic:Graphic=lstEvent.selectedItem as  Graphic;//获取事故列表某项数据，转换graphic
                if(graphic.attributes.X==0 || graphic.attributes.Y==0){//判断事故定位数据是否合法
                    Alert.show("此事件没有坐标信息，");
                }else{
                    zoomToFeature(graphic);//跳转到定位函数 
                }
                
            }
            //定位函数
            private function zoomToFeature(feature:Graphic):void{
                var mapPoint:MapPoint = feature.geometry as MapPoint;//获取经纬度
                mapPoint.spatialReference=new SpatialReference(4326);
                this.longitudeText.text="";
                this.latitudeText.text="";
                longitudeText.text="经度："+mapPoint.x.toFixed(4).toString();
                latitudeText.text="纬度："+mapPoint.y.toFixed(4).toString();
                //                var popUpRenderer:CustomPopUpRenderer=new CustomPopUpRenderer();
                var popUpRenderer:PopUpRenderer=new PopUpRenderer();//设置气泡窗口
                //popUpRenderer.forceSetMap(this._featureLayer.map); 
                var popUpInfo:PopUpInfo=(this.graphicLayer.infoWindowRenderer as  ClassFactory).properties.popUpInfo;
                popUpInfo.showZoomToButton=true;
                popUpRenderer.popUpInfo=popUpInfo;                        
                popUpRenderer.graphic=feature;    
                //                if(!popUpRenderer.map)popUpRenderer.userMap=this.map;
                this.map.infoWindow.content=popUpRenderer;    
                this.map.level=7;
                this.map.zoomTo(feature.geometry);
                this.map.infoWindow.show(mapPoint);    
                this.addSharedData("event_point", new ArrayCollection([mapPoint]));
                var message:String="确定接入点，坐标为：x=" + mapPoint.x + " y=" + mapPoint.y; 
                doBufferByPoint(mapPoint);
            }
            
            //添加分析的方法 start
            private var lastDrawGraphic:Graphic;
            private function doBufferByPoint(mapPoint:MapPoint):void
            {
                var base:Number=Number(500);
                var classNumber:Number=Number(1);
                var interval:Number=Number(500);
                var distances:Array=[];
                if (classNumber >= 1)
                {
                    for (var i:int=0; i < classNumber; i++)
                    {
                        distances.push(base + i * interval);
                    }
                }
                doBuffer(mapPoint, distances);
                
            }
            
            
            private function doBuffer(geometry:Geometry, distances:Array):void
            {
                var radius:Number=Number(500);
                var param:BufferParameters=new BufferParameters();
                param.geometries=[geometry];
                param.distances=distances;
                //param.geodesic=true;
                //4326需要加上这个单位
                param.unit=GeometryService.UNIT_METER;
                //param.outSpatialReference=new SpatialReference(4326);
                geometryService.buffer(param);
                
                lastDrawGraphic = new Graphic(geometry);    
                var label:String = "面积：" + numFormatter.format(3.14*radius*radius/1000000) + "平方千米";
                label += "
" + "半径：" + numFormatter.format(radius/1000) + "千米";
                addDrawLabel(label, lastDrawGraphic);
            }
            
            private function addDrawLabel(label:String, lastDrawnGraphic:Graphic):void
            {
                var txtSym:TextSymbol = new TextSymbol(label);
                txtSym.yoffset = 8;
                var txtFormat:TextFormat = new TextFormat("Arial", 12, 0x000000, true); // black label
                txtSym.textFormat = txtFormat;
                lastDrawnGraphic.symbol = txtSym;
            }    

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