arcgis js（九）地理处理任务缓冲区分析

待我称王封你为后i 2022-09-07 09:13 200阅读 0赞

1、基于上一节的讲解我们已经知道如何**发布GP服务**，[arcgis js（九）地理处理任务0 发布GP服务\_郝大大的博客-CSDN博客][arcgis js_0 _GP_-CSDN]，接下来进入正题，后面会分节介绍如何进行调用和处理众多的地理任务，给从事本专业的高校学生或者对GIS感兴趣的开发者提供一个学习思路，满足大家对地理信息处理的迫切需求。

2、在查看了各种资料后发现esri在api提供了两种方式，一个是**Geoprocessor**，位于**esri/tasks**，另一个是**geoprocessor**，位于**esri/rest**，我们来看看它们的区别：** Geoprocessor自从4.0版本后支持，但是自从4.20版本之后被舍弃掉了，geoprocessor自从4.19版本后支持，所以根据版本自行选择。**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0hCX1Byb2dyYW1tZXI_size_16_color_FFFFFF_t_70][]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0hCX1Byb2dyYW1tZXI_size_16_color_FFFFFF_t_70 1][]

3、依然是基于天地图底图，我们分别介绍synchronous**同步**和asynchronous**异步**执行方法，显示速度和网速也有关系。同步的url是**http://localhost:6080/arcgis/rest/services/buf/GPServer**，在浏览器打开，可以看到执行方式，同时要注意Tasks:模型，在**调用的时候一定要加上任务的名字**，否则会失败，在代码中设置的url为：**http://localhost:6080/arcgis/rest/services/buf/GPServer/模型**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0hCX1Byb2dyYW1tZXI_size_16_color_FFFFFF_t_70 2][]

4、同步方法

<html>
    
    <head>
        <meta charset="utf-8" />
        <meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no" />
        <title> Geoprocessing </title>
        <style>
            html,
            body,
            #viewDiv {
                padding: 0;
                margin: 0;
                height: 100%;
                width: 100%;
            }
    
            #paneDiv {
                position: absolute;
                top: 18px;
                right: 18px;
                padding: 12px;
                background-color: rgba(0, 0, 0, 0.5);
                color: white;
                width: 200px;
            }
        </style>
    
        <link rel="stylesheet" href="https://js.arcgis.com/4.20/esri/themes/light/main.css" />
        <script src="https://js.arcgis.com/4.20/"></script>
    
        <script>
            require([
                "esri/Map",
                "esri/views/MapView",
                "esri/layers/GraphicsLayer",
                "esri/Graphic",
                "esri/geometry/Point",
                "esri/rest/geoprocessor",
                "esri/rest/support/LinearUnit",
                "esri/rest/support/FeatureSet",
                "esri/layers/WebTileLayer",
                "esri/layers/support/TileInfo",
                "esri/geometry/SpatialReference",
            ], (
                Map,
                MapView,
                GraphicsLayer,
                Graphic,
                Point,
                geoprocessor,
                LinearUnit,
                FeatureSet,
                WebTileLayer,
                TileInfo,
                SpatialReference
            ) => {
    
                var tiandituBaseUrl = "http://{subDomain}.tianditu.com"; //天地图服务地址
                var token = ""; //天地图token，在官网申请
                var tileInfo = new TileInfo({
                    "rows": 256,
                    "cols": 256,
                    "origin": {
                        "x": -180,
                        "y": 90
                    },
                    "spatialReference": {
                        "wkid": 4490
                    },
                    "lods": [
                        { "level": "1", "scale": 295829355.45, "resolution": 0.703125 },
                        { "level": "2", "scale": 147914677.725, "resolution": 0.3515625 },
                        { "level": "3", "scale": 73957338.8625, "resolution": 0.17578125 },
                        { "level": "4", "scale": 36978669.43125, "resolution": 0.087890625 },
                        { "level": "5", "scale": 18489334.715625, "resolution": 0.0439453125 },
                        { "level": "6", "scale": 9244667.3578125, "resolution": 0.02197265625 },
                        { "level": "7", "scale": 4622333.67890625, "resolution": 0.010986328125 },
                        { "level": "8", "scale": 2311166.839453125, "resolution": 0.0054931640625 },
                        { "level": "9", "scale": 1155583.4197265625, "resolution": 0.00274658203125 },
                        { "level": "10", "scale": 577791.7098632812, "resolution": 0.001373291015625 },
                        { "level": "11", "scale": 288895.8549316406, "resolution": 0.0006866455078125 },
                        { "level": "12", "scale": 144447.9274658203, "resolution": 0.00034332275390625 },
                        { "level": "13", "scale": 72223.96373291015, "resolution": 0.000171661376953125 },
                        { "level": "14", "scale": 36111.98186645508, "resolution": 0.0000858306884765625 },
                        { "level": "15", "scale": 18055.99093322754, "resolution": 0.00004291534423828125 },
                        { "level": "16", "scale": 9027.99546661377, "resolution": 0.000021457672119140625 },
                        { "level": "17", "scale": 4513.997733306885, "resolution": 0.000010728836059570312 },
                        { "level": "18", "scale": 2256.9988666534423, "resolution": 0.000005364418029785156 },
                        { "level": "19", "scale": 1128.4994333267211, "resolution": 0.000002682209014892578 }
                    ]
                });
    
                //影像地图
                var tdtImageLayer = new WebTileLayer({
                    urlTemplate: tiandituBaseUrl + "/DataServer?T=img_c&x={col}&y={row}&l={level}&tk=" + token,
                    subDomains: ["t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7"],
                    tileInfo: tileInfo,
                    spatialReference: { wkid: 4490 },
                });
    
                //影像注记
                var tdtAnnoImageLayer = new WebTileLayer({
                    urlTemplate: tiandituBaseUrl + "/DataServer?T=cia_c&x={col}&y={row}&l={level}&tk=" + token,
                    subDomains: ["t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7"],
                    tileInfo: tileInfo,
                    spatialReference: { wkid: 4490 },
                });
    
                const gpUrl = "http://localhost:6080/arcgis/rest/services/buf/GPServer/模型";
    
                //定位到济南市中心
                var cityCenter = new Point(116.985, 36.671, new SpatialReference({ wkid: 4490 }));
    
                // 创建地图
                var map = new Map({
                    basemap: {
                        baseLayers: [tdtImageLayer, tdtAnnoImageLayer]
                    },
                });
    
                //添加到view
                var view = new MapView({
                    container: "viewDiv",
                    map: map,
                    center: cityCenter,
                    zoom: 14,
                    ui: {
                        components: ["zoom", "compass"]
                    }
                });
    
                //创建显示图层
                const graphicsLayer = new GraphicsLayer();
                map.add(graphicsLayer);
    
                //创建点符号样式
                const markerSymbol = {
                    type: "simple-marker",
                    color: [255, 0, 0],
                    outline: {
                        color: [255, 255, 255],
                        width: 2
                    }
                };
    
                //创建面符号样式
                const fillSymbol = {
                    type: "simple-fill",
                    color: [226, 119, 40, 0.75],
                    outline: {
                        color: [255, 255, 255],
                        width: 1
                    },
                };
    
                //输出参考
                const options = {
                    outSpatialReference: {
                        wkid: 4490
                    }
                };
    
                //单击事件
                view.on("click", computeViewshed);
    
                function computeViewshed(event) {
                    graphicsLayer.removeAll();
    
                    const point = new Point({
                        longitude: event.mapPoint.longitude,
                        latitude: event.mapPoint.latitude
                    });
    
                    const inputGraphic = new Graphic({
                        geometry: point,
                        symbol: markerSymbol
                    });
    
                    graphicsLayer.add(inputGraphic);
    
                    //设置输入数据集
                    const inputGraphicContainer = [];
                    inputGraphicContainer.push(inputGraphic);
                    const featureSet = new FeatureSet();
                    featureSet.features = inputGraphicContainer;
    
                    //设置缓冲区距离
                    const dis = new LinearUnit();
                    dis.distance = 100;
                    dis.units = "meters";
    
                    const params = {
                        input: featureSet,
                        dis: dis
                    };
    
                    //执行gp task
                    geoprocessor.execute(gpUrl, params, options).then(drawResultData);
                }
    
                //执行结果
                function drawResultData(result) {
                    const resultFeatures = result.results[0].value.features;
    
                    //显示缓冲区
                    const graphic = resultFeatures.map((feature) => {
                        feature.symbol = fillSymbol;
                        return feature;
                    });
                    graphicsLayer.addMany(graphic);
    
                    view.goTo({
                        target: graphic,
                        tilt: 0
                    }).catch((error) => {
                        if (error.name != "AbortError") {
                            console.error(error);
                        }
                    });
                }
            });
        </script>
    </head>
    
    <body>
        <div id="viewDiv"></div>
        <div id="paneDiv" class="esri-widget">
            在地图上单击执行 GP Task
        </div>
    </body>
    
    </html>

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0hCX1Byb2dyYW1tZXI_size_16_color_FFFFFF_t_70 3][]

5、异步方法

打开链接**http://localhost:6080/arcgis/rest/services/bufferpoint/GPServer**可以看到执行类型是异步的：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0hCX1Byb2dyYW1tZXI_size_16_color_FFFFFF_t_70 4][]

[arcgis js_0 _GP_-CSDN]: https://blog.csdn.net/HB_Programmer/article/details/119837395
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