wabapp.js编写js代码，本例子的js代码分为3部分功能，第一载入地图进行显示；第二进行画点、线、面操作；第三根据画的点、线、面图形进行buffer分析。具体的说明看代码注释：
dojo.require("esri.map");
dojo.require("esri.tasks.geometry");
dojo.require("esri.toolbars.draw");
dojo.require("esri.tasks.query");
djConfig = { isDebug:true };
var map,tb,geometryService,queryTask,query;
function init()
{
startExtent = new esri.geometry.Extent(-183.780014745329,16.2975638854873,-61.4068547410964,74.0304580085983, new esri.SpatialReference({wkid:4269}));
map = new esri.Map("map");
//底图Tile图
var imageryPrime = new esri.layers.ArcGISTiledMapServiceLayer("http://server.arcgisonline.com/ArcGIS/rest/services/NGS_Topo_US_2D/MapServer");
map.addLayer(imageryPrime);
var usa = new esri.layers.ArcGISDynamicMapServiceLayer("http://jh-53a435fbc0e8/ArcGIS/rest/services/USA/MapServer");
//设置要显示的图层
//usa.setVisibleLayers([0]);
//设置图层透明度
usa.setOpacity(0.8);
map.addLayer(usa);
//设置地图视图范围
map.setExtent(startExtent);
geometryService = new esri.tasks.GeometryService("http://jh-53a435fbc0e8/ArcGIS/rest/services/Geometry/GeometryServer");
tb = new esri.toolbars.Draw(map);
dojo.connect(tb, "onDrawEnd", doDraw);
}
//画图
function doDraw(geometry)
{
//根据图形的类型定义显示样式
switch (geometry.type)
{
case "point":
var symbol = new esri.symbol.SimpleMarkerSymbol(esri.symbol.SimpleMarkerSymbol.STYLE_SQUARE, 10, new esri.symbol.SimpleLineSymbol(esri.symbol.SimpleLineSymbol.STYLE_SOLID, new dojo.Color([255,0,0]), 1), new dojo.Color([0,255,0,0.25]));
break;
case "polyline":
var symbol = new esri.symbol.SimpleLineSymbol(esri.symbol.SimpleLineSymbol.STYLE_DASH, new dojo.Color([255,0,0]), 1);
break;
case "polygon":
var symbol = new esri.symbol.SimpleFillSymbol(esri.symbol.SimpleFillSymbol.STYLE_SOLID, new esri.symbol.SimpleLineSymbol(esri.symbol.SimpleLineSymbol.STYLE_SOLID, new dojo.Color([0,0,0]), 1), new dojo.Color([255,0,0,0.25]));
break;
}
//把绘制的图形添加到map.graphics进行显示
var graphic = new esri.Graphic(geometry, symbol);
map.graphics.add(graphic);
//如果是面需要先进行simplify操作，否则直接进行buffer
if(geometry.type === "polygon")
{
geometryService.simplify([graphic],doSimplify);
}
else
{
doBuffer([graphic]);
}
}
//simplify结束调用buffer
function doSimplify(graphics)
{
doBuffer(graphics);
}
function doBuffer(graphics)
{
//buffer参数
var params = new esri.tasks.BufferParameters();
//buffer的范围值，从输入框中获取
params.distances = [ dojo.byId("distance").value ];
//空间参考
params.bufferSpatialReference =new esri.SpatialReference({wkid: dojo.byId("wkid").value});
//输出结果的空间参考
params.outSpatialReference = map.spatialReference;
params.features = graphics;
//buffer的单位，从列表框获取
params.unit = eval("esri.tasks.BufferParameters."+dojo.byId("unit").value);
//buffer操作
geometryService.buffer(params,showBuffer);
}
//显示buffer的结果
function showBuffer(features)
{
var symbol = new esri.symbol.SimpleFillSymbol(esri.symbol.SimpleFillSymbol.STYLE_SOLID,new esri.symbol.SimpleLineSymbol(esri.symbol.SimpleLineSymbol.STYLE_SOLID,new dojo.Color([255,0,0,0.65]), 2),new dojo.Color([255,0,0,0.35]));
for (var j=0;j<features.length;j++)
{
var graphic = new esri.Graphic(features[j].geometry,symbol);
map.graphics.add(graphic);
}
tb.deactivate();
map.showZoomSlider();
}
dojo.addOnLoad(init);
5、这样就完成了buffer的例子。