arcgis api for flex求线段的起点，终点和中点

private function getCenter(pl：Polyline):MapPoint{
var pathCount:Number=pl.paths.length;
var pathIndex:int=int((pathCount / 2) - 1);
var midPath:Array=pl.paths[pathIndex];
var ptCount:Number=midPath.length;
var ptIndex:int=int((ptCount / 2) - 1);
var pt:MapPoint=pl.getPoint(pathIndex, ptIndex);
return pt;
}

var xx:int=LuduanList.selectedIndex;
var myGraphic:Graphic=GraphicArr[xx];
var l:Polyline=myGraphic.geometry as Polyline;

var goldPath:Array=l.paths[l.paths.length-1];

var spt:MapPoint=l.getPoint(0,0);

var mpt:MapPoint=l.getPoint(l.paths.length-1,goldPath.length-1);