Web GIS 离线解决方案

1、背景

在离线环境下(局域网中)的GIS系统中如何使用地图?这里的地图主要指的是地图底图,有了底图切片数据,我们就可以看到地图,在上面加上自己的业务数据图层,进行相关操作。

要在离线环境下看到GIS地图,就要有底图切片数据,地图的底图切片数据在一定时间内是不会变化的,可以使用一些地图下载器下载地图切片,如这个地图下载器

在CS系统中可以基于GMap.Net来做,参考《百度谷歌离线地图解决方案》。

下面介绍下Web系统如何使用GIS切片数据,开发web GIS系统。

2、使用GeoWebCache发布WMS服务

Geowebcache是基于Java的Web开源项目,主要用于缓存各种WMS数据源的地图瓦片,它实现了多种服务接口,包括WMS-C,WMTS,TMS,KML。

Geowebcache作为一个独立的开源项目,在最近被Geosever的几个版本所集成,主要是对发布的WMS图层建立缓存切片。

服务发布步骤:

1)官网下载 geowebcache-1.8.0-war.zip,直接解压得到geowebcache.war文件,将该文件直接拷贝至tomcat目录下的webapps下即可,启动tomcat会对war包进行解压。

2)修改geowebcache的配置文件geowebcache-core-context.xml。该文件在Tomcat的webapps\geowebcache\WEB-INF下,修改如下:

<bean id="gwcXmlConfig" class="org.geowebcache.config.XMLConfiguration">
<constructor-arg ref="gwcAppCtx" />
<!--<constructor-arg ref="gwcDefaultStorageFinder" />-->
    <constructor-arg value="D:\\GisMap\\" />
<!-- By default GWC will look for geowebcache.xml in {GEOWEBCACHE_CACHE_DIR},
         if not found will look at GEOSEVER_DATA_DIR/gwc/
         alternatively you can specify an absolute or relative path to a directory
         by replacing the gwcDefaultStorageFinder constructor argument above by the directory
         path, like constructor-arg value="/etc/geowebcache"     
    -->
<property name="template" value="/geowebcache.xml">
<description>Set the location of the template configuration file to copy over to the
        cache directory if one doesn't already exist.
</description>
</property>
</bean>

修改gwcXmlConfig实例化时使用固定路径,该路径可以为任意新建路径文件夹。Geowebcache启动之后会检查此文件夹下是否存在gewebcache.xml文件,如果不存在则按模板新建立并读取使用,如果存在则直接读取使用。

3)修改第2步中的gewebcache.xml文件:

<layers>
    <arcgisLayer>
        <name>ARCGIS-Demo</name>
        <tilingScheme>D:\\GisMap\\Layer\\conf.xml</tilingScheme>
        <tileCachePath>D:\\GisMap\\Layer\\_alllayers</tileCachePath>
    </arcgisLayer>
</layers>

在layers节点里添加arcgisLayer节点(默认生成的gewebcache.xml的layers节点有许多其他冗余数据,可删除可保留)。Name节点表示待添加图层的名称(这里配置为ARCGIS-Demo),titlingscheme节点为conf.xml文件的路径,tileCachePath为瓦片数据的路径。

4)瓦片地图的准备

其中conf.xml为配置文件,conf.cdi为显示区域约束文件,_alllayers文件夹下则存放了切片数据,Status.gdb为切片状态情况记录(可直接删除)。

通过瓦片下载器下载瓦片地图,然后生成的切片数据_alllayers文件夹:

L01-L10表示地图缩放级数,按照ArcGIS切片目录组织,切片命名规则也和ArcGIS切片数据命名规则一致。(conf.xml、conf.cdi和_alllayers在同级目录)。

5)启动tomcat,继而启动Geowebcache服务,浏览器访问 localhost:8080/geowebcache,如果一切正确的话可以看到下面的页面

该页面简单说明了Geowebcache的一些情况。

点击“A list of all the layers and automatic demos”连接可以看到下面:

该页面显示了geowebcache.xml配置的图层信息。图中可以看到只配置了一个名字为ARCGIS-Demo的图层,使用的EPSG3857坐标系,发布的图片格式为png格式,点击png链接即可看到瓦片地图。

这里地图显示的级别和坐标系配置都来自conf.xml文件。这里的前端js使用的是Openlayers。查看网页源码:

<html xmlns="http://www.w3.org/1999/xhtml"><head>
<meta http-equiv="imagetoolbar" content="no">
<title>ARCGIS-Demo EPSG:3857_ARCGIS-Demo image/png</title>
<style type="text/css">
body { font-family: sans-serif; font-weight: bold; font-size: .8em; }
body { border: 0px; margin: 0px; padding: 0px; }
#map { width: 85%; height: 85%; border: 0px; padding: 0px; }
</style>
<script src="../openlayers/OpenLayers.js"></script>    
<script type="text/javascript">               
var map, demolayer;                               
  // sets the chosen modifiable parameter        
  function setParam(name, value){                
   str = "demolayer.mergeNewParams({" + name + ": '" + value + "'})" 
   // alert(str);                                   
   eval(str);                                    
  }                                              
OpenLayers.DOTS_PER_INCH = 96.0;
OpenLayers.Util.onImageLoadErrorColor = 'transparent';
function init(){
var mapOptions = { 
resolutions: [156543.033928, 78271.5169639999, 39135.7584820001, 19567.8792409999, 9783.93962049996, 4891.96981024998, 2445.98490512499, 1222.99245256249, 611.49622628138, 305.748113140558, 152.874056570411, 76.4370282850732, 38.2185141425366, 19.1092570712683, 9.55462853563415, 4.77731426794937, 2.38865713397468, 1.19432856685505, 0.597164283559817, 0.298582141647617],
projection: new OpenLayers.Projection('EPSG:3857'),
maxExtent: new OpenLayers.Bounds(-20037508.342787,-20037508.342780996,20037508.342780996,20037508.342787),
units: "meters",
controls: []
};
map = new OpenLayers.Map('map', mapOptions );
map.addControl(new OpenLayers.Control.PanZoomBar({
        position: new OpenLayers.Pixel(2, 15)
}));
map.addControl(new OpenLayers.Control.Navigation());
map.addControl(new OpenLayers.Control.Scale($('scale')));
map.addControl(new OpenLayers.Control.MousePosition({element: $('location')}));
demolayer = new OpenLayers.Layer.WMS(
"ARCGIS-Demo","../service/wms",
{layers: 'ARCGIS-Demo', format: 'image/png' },
{ tileSize: new OpenLayers.Size(256,256),
 tileOrigin: new OpenLayers.LonLat(-2.0037508342787E7, 2.0037508342787E7)});
map.addLayer(demolayer);
map.zoomToExtent(new OpenLayers.Bounds(-20037497.2108,-19929239.113399997,20037497.2108,18379686.9965));
// The following is just for GetFeatureInfo, which is not cached. Most people do not need this 
map.events.register('click', map, function (e) {
  document.getElementById('nodelist').innerHTML = "Loading... please wait...";
  var params = {
    REQUEST: "GetFeatureInfo",
    EXCEPTIONS: "application/vnd.ogc.se_xml",
    BBOX: map.getExtent().toBBOX(),
    X: e.xy.x,
    Y: e.xy.y,
    INFO_FORMAT: 'text/html',
    QUERY_LAYERS: map.layers[0].params.LAYERS,
    FEATURE_COUNT: 50,
    Layers: 'ARCGIS-Demo',
    Styles: '',
    Srs: 'EPSG:3857',
    WIDTH: map.size.w,
    HEIGHT: map.size.h,
    format: "image/png" };
  OpenLayers.loadURL("../service/wms", params, this, setHTML, setHTML);
  OpenLayers.Event.stop(e);
  });
}
function setHTML(response){
    document.getElementById('nodelist').innerHTML = response.responseText;
};
</script>
</head>
<body onload="init()">
<div id="params"></div>
<div id="map"></div>
<div id="nodelist"></div>
</body>
</html>

个人比较喜欢leaflet这个GIS javascript库,使用leaflet加载GeoWebCache发布的这个服务:

<!DOCTYPE html>
<html>
<head>
    <title>Leaflet - Offline Demo</title>
    <link rel="stylesheet" href="https://unpkg.com/leaflet@1.0.3/dist/leaflet.css" />
    <script src="https://unpkg.com/leaflet@1.0.3/dist/leaflet.js"></script>
</head>
<body>
    <div id="map" style="height:100vh;" ></div>
    <script type="text/javascript">
        
    var mapCenter = new L.LatLng(32.1280, 118.7742); //南京
        
    var map = new L.Map('map', {
        center : mapCenter,
        zoom : 4
    });

    var wmsLayer = L.tileLayer.wms("http://localhost:8080/geowebcache/service/wms", {
        layers: 'ARCGIS-Demo',
        format: 'image/png'
    });
    wmsLayer.addTo(map);

    var marker = new L.Marker(mapCenter);
    map.addLayer(marker);
    marker.bindPopup("<p>Hello! ;}</p>").openPopup();
        
    </script>
</body>
</html>

3、使用自定义的Http服务

GeowebCache本质上就是个Http服务,通过请求参数获取配置文件中的路径中的切片数据,返回给请求方。

我们可以自己写个独立的Http服务,从数据库中读取切片数据返回给请求方。

切片请求地址类似:http://localhost:8899/1818940751/{z}/{x}/{y}

其中“1818940751”是下载器下载的地图类型,z/x/y分别是zoom和地图切片行列号。

前端js使用leaflet加载:

var amapNormalUrl = 'http://localhost:8899/788865972/{z}/{x}/{y}';
var amapNormalLayer = new L.TileLayer(amapNormalUrl, {
    minZoom : 1,
    maxZoom : 18,
    attribution : '高德普通地图'
});

var mapCenter = new L.LatLng(32.1280, 118.7742); //南京
var map = new L.Map('map', {
        center : mapCenter,
        zoom : 9,
        minZoom: 1,
        maxZoom: 18,
        layers : [ amapNormalLayer ]
});

前端js可以自定义投影Projection算法,而国内google地图、高德地图和腾讯地图都是标准的墨卡托投影,可以直接用leaflet加载。

配合一些画图插件,再配合一些后台POI检索服务,如:

使用Lucene索引和检索POI数据

使用Solr进行空间搜索

则能做出如下效果:

总结:介绍了如何使用下载的离线切片数据在局域网环境下发布Web GIS地图服务,前端配合使用一些js插件,实现web下空间数据的检索。

自定义的Http地图服务代码:https://github.com/luxiaoxun/Code4Java

附件:

conf.cdi

<?xml version="1.0" encoding="utf-8" ?>
<EnvelopeN xsi:type='typens:EnvelopeN' 
    xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' 
    xmlns:xs='http://www.w3.org/2001/XMLSchema' 
    xmlns:typens='http://www.esri.com/schemas/ArcGIS/10.1'>
    
    <XMin>-20037497.2108</XMin>
    <YMin>-19929239.113399997</YMin>
    <XMax>20037497.2108</XMax>
    <YMax>18379686.9965</YMax>

</EnvelopeN>

conf.xml

<?xml version="1.0" encoding="utf-8"?>
<CacheInfo xsi:type="typens:CacheInfo" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:typens="http://www.esri.com/schemas/ArcGIS/10.1">
    <TileCacheInfo xsi:type="typens:TileCacheInfo">
        <SpatialReference xsi:type="typens:ProjectedCoordinateSystem">
            <WKT>PROJCS["WGS_1984_Web_Mercator_Auxiliary_Sphere",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Mercator_Auxiliary_Sphere"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",0.0],PARAMETER["Standard_Parallel_1",0.0],PARAMETER["Auxiliary_Sphere_Type",0.0],UNIT["Meter",1.0],AUTHORITY["EPSG",3857]]</WKT>
            <XOrigin>-20037700</XOrigin>
            <YOrigin>-30241100</YOrigin>
            <XYScale>148923141.92838538</XYScale>
            <ZOrigin>-100000</ZOrigin>
            <ZScale>10000</ZScale>
            <MOrigin>-100000</MOrigin>
            <MScale>10000</MScale>
            <XYTolerance>0.001</XYTolerance>
            <ZTolerance>0.001</ZTolerance>
            <MTolerance>0.001</MTolerance>
            <HighPrecision>true</HighPrecision>
            <WKID>3857</WKID>
        </SpatialReference>
        
        <TileOrigin xsi:type="typens:PointN">
            <X>-20037508.342787001</X>
            <Y>20037508.342787001</Y>
        </TileOrigin>
    
        <TileCols>256</TileCols>
        <TileRows>256</TileRows>
        <DPI>96</DPI>
        <LODInfos xsi:type="typens:ArrayOfLODInfo">
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>0</LevelID>
                <Scale>591657527.591555</Scale>
                <Resolution>156543.03392799999</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>1</LevelID>
                <Scale>295828763.79577702</Scale>
                <Resolution>78271.516963999893</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>2</LevelID>
                <Scale>147914381.89788899</Scale>
                <Resolution>39135.758482000099</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>3</LevelID>
                <Scale>73957190.948944002</Scale>
                <Resolution>19567.879240999901</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>4</LevelID>
                <Scale>36978595.474472001</Scale>
                <Resolution>9783.9396204999593</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>5</LevelID>
                <Scale>18489297.737236001</Scale>
                <Resolution>4891.9698102499797</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>6</LevelID>
                <Scale>9244648.8686180003</Scale>
                <Resolution>2445.9849051249898</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>7</LevelID>
                <Scale>4622324.4343090001</Scale>
                <Resolution>1222.9924525624899</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>8</LevelID>
                <Scale>2311162.2171550002</Scale>
                <Resolution>611.49622628138002</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>9</LevelID>
                <Scale>1155581.108577</Scale>
                <Resolution>305.74811314055802</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>10</LevelID>
                <Scale>577790.55428899999</Scale>
                <Resolution>152.874056570411</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>11</LevelID>
                <Scale>288895.27714399999</Scale>
                <Resolution>76.437028285073197</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>12</LevelID>
                <Scale>144447.638572</Scale>
                <Resolution>38.218514142536598</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>13</LevelID>
                <Scale>72223.819285999998</Scale>
                <Resolution>19.109257071268299</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>14</LevelID>
                <Scale>36111.909642999999</Scale>
                <Resolution>9.5546285356341496</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>15</LevelID>
                <Scale>18055.954822</Scale>
                <Resolution>4.7773142679493699</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>16</LevelID>
                <Scale>9027.9774109999998</Scale>
                <Resolution>2.38865713397468</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>17</LevelID>
                <Scale>4513.9887049999998</Scale>
                <Resolution>1.1943285668550501</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>18</LevelID>
                <Scale>2256.994353</Scale>
                <Resolution>0.59716428355981699</Resolution>
            </LODInfo>
            <LODInfo xsi:type="typens:LODInfo">
                <LevelID>19</LevelID>
                <Scale>1128.4971760000001</Scale>
                <Resolution>0.29858214164761698</Resolution>
            </LODInfo>
        </LODInfos>
    </TileCacheInfo>
    <TileImageInfo xsi:type="typens:TileImageInfo">
        <CacheTileFormat>PNG</CacheTileFormat>
        <CompressionQuality>0</CompressionQuality>
        <Antialiasing>false</Antialiasing>
    </TileImageInfo>
    <CacheStorageInfo xsi:type="typens:CacheStorageInfo">
        <StorageFormat>esriMapCacheStorageModeExploded</StorageFormat>
        <PacketSize>0</PacketSize>
    </CacheStorageInfo>
</CacheInfo>

参考:

  • http://leafletjs.com/
  • http://leafletjs.com/examples/quick-start/
  • http://www.cnblogs.com/luxiaoxun/p/4454880.html
  • http://www.cnblogs.com/luxiaoxun/p/5020247.html


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