Arcgis 控制地图缩放比例

<esri:Map id="myMap"
width="100%"
height="100%"
logoVisible="false"
zoomSliderVisible="false"
load="onMapCreated(event)"
zoomEnd="onMapZoom(event)"
backgroundColor="#FFFFFF"
scaleBarVisible="false">
<esri:lods>
<esri:LOD resolution="0.0000702975"
scale="19500.04852413"/>
<esri:LOD resolution="0.000140595"
scale="39000.09704826"/>
<esri:LOD resolution="0.00028119"
scale="78000.19409652"/>
<esri:LOD resolution="0.00056238"
scale="156000.38819305"/>
</esri:lods>
<esri:extent>
<esri:Extent xmin="115.943145"
ymin="39.70972162"
xmax="116.898109"
ymax="40.12694583">
</esri:Extent>
</esri:extent>
<esri:ArcGISDynamicMapServiceLayer url="{Application.application.yjczmapURL}"/>
<esri:GraphicsLayer id="graphicLayer"
symbol="{sms}"
creationCompleteEffect="{this.myGlow}"/>
<esri:GraphicsLayer id="staGraphicLayer"/>
</esri:Map>
<!--渲染点闪烁-->
<mx:Glow id="myGlow"
alphaFrom="1"
alphaTo="0.3"
blurXFrom="1"
blurXTo="50"
blurYFrom="0"
blurYTo="50"
repeatCount="0"
duration="1000"
color="#FF0000"/>
<!--控制显示的比例-->
/**
* 设置默认显示范围
* **/
private function onMapCreated(event:MapEvent):void
{
this.myMap.scale=200000;
}

/**
* 控制地图显示比例
* **/
private function onMapZoom(event:ZoomEvent):void
{
//最小
if (this.myMap.scale > 200000)
{
this.myMap.scale=250000;
}
//最大
if (this.myMap.scale < 50000)
{
this.myMap.scale=250000;
}

}