如何正确响应ArcGIS JavaScript API中图形的鼠标事件

在使用ArcGIS JavaScript API编写程序的时候，程序员往往需要完成这样一个功能：点击地图上的图形，自动进行专题GIS数据查询，当在地图非图形区域上点击时，自动进行底图兴趣点查询。

由于专题GIS图形是叠加在底图上的，所以我们在处理地图的鼠标点击事件时，就需要根据实际点击的位置和内容来对不同的数据进行查询。

ArcGIS JavaScript API为编程人员分别提供了针对地图对象和图形的两个鼠标点击事件。

下面是示例代码：

 <!DOCTYPE html>
 <html>
   <head>
     <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
     <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no" />
     <title>Test Map</title>
     <link rel="stylesheet" href="http://localhost/arcgis_js_api/library/3.17/3.17/dijit/themes/claro/claro.css" />
     <link rel="stylesheet" href="http://localhost/arcgis_js_api/library/3.17/3.17/esri/css/esri.css" />
     <style>
       html, body, #ui-map-view {
         margin: 0;
         padding: 0;
         width: 100%;
         height: 100%;
       }
     </style>
     <script src="http://localhost/arcgis_js_api/library/3.17/3.17/init.js"></script>
     <script>
       var myMap;
       require([
         "esri/layers/ArcGISTiledMapServiceLayer",
         "esri/symbols/SimpleMarkerSymbol",
         "esri/map",
         "dojo/on",
         "esri/graphic",
         "esri/geometry/Point",
         "dojo/domReady!"
       ], function ( TileLayer,SimpleMarkerSymbol, Map, on,Graphic,Point){
         var layer = new TileLayer(
           "https://www.seanpc.com/ags/rest/services/WorldBaseMap/MapServer"
         );
         myMap = new Map("ui-map-view",{
           center: [-111.87, 40.57]
         });
         myMap.addLayer(layer);
 　　　　//地图鼠标点击响应事件
         on(myMap,"click",function(e){
           alert("map clicked");
         });

        myMap.on("load", function() {//图形鼠标点击响应事件
         myMap.graphics.on("click",function(e){
           alert("graphic clicked");
           e.stopPropagation();
         });
         var g=new Graphic();
         g.setGeometry(new Point([-111.87, 40.57]));
          var simpleMarkerSymbol = new SimpleMarkerSymbol();
          g.setSymbol(simpleMarkerSymbol);
         myMap.graphics.add(g);
         });
       });
     </script>
   </head>
   <body class="claro">
     <div id="ui-map-view"></div>
   </body>
 </html>