官方的例子这部分很清楚。

应用都是很简单的复制粘贴，此处不再赘述。
可以将官方的代码封装成接口，方便开发使用

贴代码
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title>地图打印</title>
    <link rel="stylesheet" href="https://js.arcgis.com/3.28/esri/css/esri.css" />
    <script src="https://js.arcgis.com/3.28/"></script>
    <script  src="https://code.jquery.com/jquery-1.12.4.js"></script>
    <style type="text/css">
        .MapClass{
            width:100%;
            height:500px;
            border:1px solid #000;
        }
    </style>
    <script type="text/javascript">

        require(["esri/map",
            "dojo/dom","dojo/on","dojo/query",
            "esri/layers/ArcGISDynamicMapServiceLayer",
            "esri/symbols/SimpleMarkerSymbol",
            "esri/symbols/SimpleLineSymbol",
            "esri/symbols/SimpleFillSymbol",
            "esri/toolbars/draw",
            "esri/graphic",
            "esri/tasks/PrintTask",
            "esri/tasks/PrintTemplate",
            "esri/tasks/PrintParameters",
            "dojo/colors",
            "dojo/domReady!"],
            function (Map,dom,on,query,
                ArcGISDynamicMapServiceLayer,
                SimpleMarkerSymbol,
                SimpleLineSymbol,
                SimpleFillSymbol,
                Draw,
                Graphic,
                PrintTask,PrintTemplate,PrintParameters,
                Color) {
                var map = new esri.Map("mapDiv");
                var layer = new esri.layers.ArcGISDynamicMapServiceLayer
                ("http://localhost:6080/arcgis/rest/services/ecology/beijing_2012_3/MapServer");
                map.addLayer(layer);
                //创建绘图对象
                var toolBar = new Draw(map);    
                //线符号
                lineSymbol = new SimpleLineSymbol(SimpleLineSymbol.STYLE_DASH, new Color([255, 0, 0]), 3);
                //面符号
                polygonSymbol = new SimpleFillSymbol(SimpleFillSymbol.STYLE_SOLID, lineSymbol, new Color([255, 0, 0, 0.25]));

                //给绘制polygon的按钮绑定事件
                query(".pbtn").on("click",function(event){
                    //激活绘制多边形
                    toolBar.activate(Draw.POLYGON, {
                        showTooltips:true
                    })

                })
                //绘图结束绑定事件
                on(toolBar,"draw-end",function(result){
                    //获得面形状
                    var geometry=result.geometry;
                    //创建Graphic
                    var graphicpoint= new Graphic(geometry, polygonSymbol);
                    map.graphics.add(graphicpoint); 
                    //关闭绘图工具
                    toolBar.deactivate();                    
                })
                //给地图打印按钮绑定事件
                on(dom.byId("Btn"),"click",function(){
                    //创建地图打印对象
                    var printMap = new PrintTask("http://localhost:6080/arcgis/rest/services/Utilities/PrintingTools/GPServer/Export%20Web%20Map%20Task");
                    //创建地图打印模版
                    var template = new PrintTemplate();
                    //创建地图的打印参数，参数里面包括：模版和地图
                    var params = new PrintParameters(); 
                    //输出图片的空间参考
                    printMap.outSpatialReference = map.SpatialReference    
                    //打印图片的各种参数
                    template.exportOptions = { 
                        width: 850, 
                        height: 650, 
                        dpi: 96 
                    };
                    //打印输出的格式
                    template.format = "PDF"; 
                    //输出地图的布局
                    template.layout = "MAP_ONLY"; 
                    PrintTemplate 
                    //设置参数地图
                    params.map = map; 
                    //设置参数模版
                    params.template = template; 
                    //运行结果
                    printMap.execute(params, function(result){
                        if (result != null) { 
                            //网页打开生成的地图
                            window.open(result.url); 
                        } 
                    }) 
                })

            });
    </script>
</head>
<body>
    <div id="mapDiv" class="MapClass"></div>
    <button class="pbtn" >画多边形</button>
    <input id="Btn" type="button" value="地图打印" />
</body>
</html>