Android老大哥安迪魯賓近日在發(fā)布2.3姜餅系統(tǒng)和Nexus S的時(shí)候曾演示了最新版本的Google Maps 5.0手機(jī)地圖，最大的變化就是采用了全3D地圖。

在新版手機(jī)地圖中，矢量圖將替換原本的2D畫面為用戶呈現(xiàn)出全新的3D界面，用戶可以自由的轉(zhuǎn)動(dòng)和縮放。此外用戶還將會(huì)獲得離線地圖瀏覽功能，不用在瀏覽地圖時(shí)保持在線狀態(tài)。

Google現(xiàn)在在其官方手機(jī)頻道又放出了一段用Nexus S運(yùn)行新版Maps應(yīng)用的全功能演示，這款軟件將會(huì)隨Nexus S上市，之后提供其他設(shè)備更新，但是對手機(jī)硬件有一定的要求，新款800MHz至1GHz處理器且配有專用圖形核心的手機(jī)才能支持3D視圖。

原文見驅(qū)動(dòng)之家
http://news.mydrivers.com/1/181/181818.htm
天地圖官方網(wǎng)站提供的二次開發(fā)文檔和例子過于簡單，很多關(guān)鍵信息沒有給予說明，例如給出了WFS服務(wù)接口，卻沒有提供詳細(xì)的開發(fā)文檔。
不過這并不影響我們的使用，因?yàn)镺GC WFS規(guī)范包含元數(shù)據(jù)查詢命令，通過發(fā)送getCapabilities請求，我們可以得知服務(wù)器提供哪些WFS服務(wù)。

獲取WFS服務(wù)器元數(shù)據(jù)
http://search.tianditu.com/wfs?request=getCapabilities
返回信息如下：
<WFS_Capabilities version="1.0.0" xsi:schemaLocation="http://www.opengis.net/wfs http://schemas.opengeospatial.net//wfs/1.0.0/WFS-capabilities.xsd">
<Service>
<Name>GeoGlobe WFS</Name>
<Title>GeoGlobe網(wǎng)絡(luò)要素服務(wù)器</Title>
<Abstract>武大吉奧信息技術(shù)有限公司GeoGlobe網(wǎng)絡(luò)要素服務(wù)器</Abstract>
<KeywordList/>
<OnlineResource>http://search.tianditu.com:80/wfs</OnlineResource>
</Service>
<Capability>
<Request>
<GetCapabilities>
<DCPType>
<HTTP>
<Get onlineResource="http://search.tianditu.com:80/wfs"/>
</HTTP>
</DCPType>
</GetCapabilities>
<GetFeature>
<ResultFormat>
<GML2/>
</ResultFormat>
<DCPType>
<HTTP>
<Get onlineResource="http://search.tianditu.com:80/wfs"/>
<Post onlineResource="http://search.tianditu.com:80/wfs"/>
</HTTP>
</DCPType>
</GetFeature>
<DescribeFeatureType>
<SchemaDescriptionLanguage>
<XMLSCHEMA/>
</SchemaDescriptionLanguage>
<DCPType>
<HTTP>
<Get onlineResource="http://search.tianditu.com:80/wfs"/>
</HTTP>
</DCPType>
</DescribeFeatureType>
</Request>
<VendorSpecificCapabilities/>
</Capability>
<FeatureTypeList>
<Operations>
<Query/>
</Operations>
<FeatureType>
<Name>DOMAIN_POI_NEW</Name>
<Title>DOMAIN_POI_NEW</Title>
<Abstract>DOMAIN_POI_NEW</Abstract>
<Keywords>DOMAIN_POI_NEW</Keywords>
<SRS>EPSG:4326</SRS>
<LatLongBoundingBox minx="-180.0" miny="-90.0" maxx="180.0" maxy="90.0"/>
</FeatureType>
<FeatureType>
<Name>iso19112:SI_Gazetteer</Name>
<Title>iso19112:SI_Gazetteer</Title>
<SRS>EPSG:4326</SRS>
<LatLongBoundingBox minx="-180.0" miny="-90.0" maxx="180.0" maxy="90.0"/>
</FeatureType>
</FeatureTypeList>
<ogc:Filter_Capabilities>
<ogc:Spatial_Capabilities>
<ogc:Spatial_Operators>
<ogc:BBOX/>
<ogc:Equals/>
<ogc:Disjoint/>
<ogc:Intersect/>
<ogc:Touches/>
<ogc:Crosses/>
<ogc:Within/>
<ogc:Contains/>
<ogc:Overlaps/>
<ogc:Beyond/>
</ogc:Spatial_Operators>
</ogc:Spatial_Capabilities>
<ogc:Scalar_Capabilities>
<ogc:Logical_Operators/>
<ogc:Comparison_Operators>
<ogc:Simple_Comparisons/>
<ogc:Like/>
<ogc:Between/>
</ogc:Comparison_Operators>
</ogc:Scalar_Capabilities>
</ogc:Filter_Capabilities>
</WFS_Capabilities>

返回信息包含了WFS服務(wù)器的開發(fā)單位（武大吉奧），WFS圖層的名稱（DOMAIN_POI_NEW和iso19112:SI_Gazetteer），支持的邏輯操作符和空間操作符。

繼續(xù)測試
http://search.tianditu.com/wfs?request=GetFeature&version=1.0.0&typeName=DOMAIN_POI_NEW&BBOX=105.99,29.99,106,30
返回
<wfs:FeatureCollection xsi:schemaLocation="http://www.opengis.net/wfs WFS_Basic.xsd http://www.geostart.com.cn/geoglobe describe.xsd">
<gml:boundedBy>
<gml:Box>
<gml:coordinates>-180.0,-90.0 180.0,90.0</gml:coordinates>
</gml:Box>
</gml:boundedBy>
<gml:featureMember>
<DOMAIN_POI_NEW>
<OID>6764930</OID>
<Geometry>
<gml:Point srsName="-1">
<gml:coordinates>105.999183,29.995258</gml:coordinates>
</gml:Point>
</Geometry>
<DOMAINNAME>梅子村</DOMAINNAME>
<DOMAINCODE>1CHN50022400000130172</DOMAINCODE>
<NLEVEL>16</NLEVEL>
<X>105.999183</X>
<Y>29.995258</Y>
<COLDATE/>
<NAMETIME/>
<ENDTIME/>
<CLASSID/>
<STANDARDNAME>亞洲中國重慶市銅梁縣梅子村</STANDARDNAME>
<TELEPHONE/>
<ADDRESS/>
<KIND>BB80</KIND>
<ZIPCODE/>
<ADMINCODE>500224</ADMINCODE>
<POI_ID>5000000130172</POI_ID>
<PID/>
<DATATYPE>chinapoi</DATATYPE>
<FENAME/>
<locationType>
<SI_LocationType>
<name>DOMAIN_POI_NEW</name>
</SI_LocationType>
</locationType>
</DOMAIN_POI_NEW>
</gml:featureMember>
</wfs:FeatureCollection>

分析返回的GML數(shù)據(jù)，可知DOMAIN_POI_NEW是地名圖層，包含名稱、代碼、類別碼等屬性字段。

將圖層改為iso19112:SI_Gazetteer，沒有返回任何信息，google ISO19112，得到如下解釋：
DIN EN ISO 19112-2005 地理信息.通過地理標(biāo)識符的空間定位 標(biāo)準(zhǔn)號： DIN EN ISO 19112-2005 標(biāo)準(zhǔn)名稱： 地理信息.通過地理標(biāo)識符的空間定位

得到以上信息后，我們嘗試使用Openlayers獲取，即全國地名數(shù)據(jù)庫。

通過URL（GET方式）訪問“天地圖”WFS服務(wù)，可以使用OpenLayers.Request.GET類，示例代碼如下：
   //使用FEATUREID查詢

   new OpenLayers.Request.GET( {
        url : "http://search.tianditu.com/wfs?request=GetFeature",
        params: {
            typeName: "DOMAIN_POI_NEW",
            FEATUREID: "DOMAIN_POI_NEW.6649356"
        },
        callback : handler
    });

   //使用BBOX查詢

    new OpenLayers.Request.GET( {
        url : "http://search.tianditu.com/wfs?request=GetFeature",
        params: {
            typeName: "DOMAIN_POI_NEW",
            BBOX: "105.99,29.99,106,30"  //map.getExtent().toBBOX()
        },
        callback : handler
    });

說明：
url WFS服務(wù)器地址，必須加上?request=GetFeature
typeName 圖層名稱
FEATUREID WFS的圖元ID，采用標(biāo)準(zhǔn)格式： [圖層名].[OID編號]
BBOX 指定區(qū)域查詢，注意不要設(shè)置過大，否則瀏覽器可能失去響應(yīng)。

通過POST方式訪問“天地圖”WFS服務(wù)，可以使用OpenLayers.Request.POST類，示例代碼如下：

    var xmlPara = "<?xml version='1.0' encoding='UTF-8'?>"
            + "<wfs:GetFeature maxFeatures='100' service='WFS' version='1.0.0' "
            + "xmlns:wfs='http://www.opengis.net/wfs' "
            + "xmlns:gml='http://www.opengis.net/gml' "
            + "xmlns:ogc='http://www.opengis.net/ogc' "
            + "xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' "
            + "xsi:schemaLocation='http://www.opengis.net/wfs http://schemas.opengis.net/wfs/1.0.0/wfs.xsd'>"
            + "<wfs:Query typeName='iso19112:SI_Gazetteer' srsName='EPSG:4326'>"
            + "<ogc:Filter xmlns:ogc='http://www.opengis.net/ogc'>"
            + "<ogc:And><ogc:PropertyIsLike wildCard='*' singleChar='.' escape='!'>"
            + "<ogc:PropertyName>STANDARDNAME</ogc:PropertyName>"
            + "<ogc:Literal>*解放碑*</ogc:Literal>"
            + "</ogc:PropertyIsLike></ogc:And></ogc:Filter>"
            + "</wfs:Query></wfs:GetFeature>";
    
    var request = OpenLayers.Request.POST( {
        url : "http://search.tianditu.com/wfs?",
        data : xmlPara,
        callback : handler
    });
};

說明：

url WFS服務(wù)器地址

data WFS請求正文，返回的GML由回調(diào)函數(shù)handler處理

handler負(fù)責(zé)處理服務(wù)端返回的GML數(shù)據(jù)，也就是矢量化的地圖數(shù)據(jù)，根據(jù)應(yīng)用需求編寫代碼，獲取feature的通用代碼如下：
var g = new OpenLayers.Format.GML();
var features = g.read(req.responseText);
for ( var i = 0; i < features.length; ++i) {
   var feature = features[i];
   var geometry = feature.geometry;
   var attributes = feature.attributes;
}

定義過濾條件時(shí)請使用STANDARDNAME字段，不要使用DOMAINNAME字段，前者應(yīng)該有索引支持，而后者沒有，查詢速度差別很大。

經(jīng)過測試，typeName="DOMAIN_POI_NEW"和typeName="iso19112:SI_Gazetteer"都能返回結(jié)果。由于缺少官方文檔說明，不知道這兩個(gè)圖層有何區(qū)別。

嘗試使用OpenLayers.Protocol.WFS無法訪問“天地圖”WFS服務(wù)，服務(wù)器返回: 請求參數(shù)[REQUEST]的值為空或不正確。

提醒: 使用POST查詢時(shí)，頁面文件或代碼文件務(wù)必保存為utf-8編碼，如果使用gbk、gb2312編碼，漢字地名會(huì)變成亂碼，導(dǎo)致javascript代碼錯(cuò)誤。

國家測繪局2010年10月21日正式發(fā)布中國公眾版國家地理信息公共服務(wù)平臺“天地圖”，作為中國境內(nèi)數(shù)據(jù)資源最全的地理信息服務(wù)網(wǎng)站，“天地圖”將為公眾提供權(quán)威、可信、統(tǒng)一的地理信息資源。

“天地圖”公開開放了地圖數(shù)據(jù)服務(wù)接口，第三方使用者可以直接通過互聯(lián)網(wǎng)獲取地圖數(shù)據(jù)，無需授權(quán)認(rèn)證，在公眾服務(wù)信息公開方面可以說是一次非常大的進(jìn)步。
“天地圖”的在線服務(wù)數(shù)據(jù)近10TB，以下是“天地圖”提供的在線地理信息數(shù)據(jù)資源：

數(shù)據(jù)類型	數(shù)據(jù)源	級別	服務(wù)地址
線劃地圖	全球1:100萬地理底圖	2-10級	http://tile0.tianditu.com/services/A0512_EMap http://tile0.tianditu.com/services/AB0512_Anno
	全國1:25萬公開版數(shù)字地形圖	11-12級	http://tile0.tianditu.com/services/B0627_EMap1112
	全國車載導(dǎo)航	13-18級	http://tile0.tianditu.com/services/siwei0608
衛(wèi)星影像	全球250米衛(wèi)星影像 (MODIS)	2-7級	http://tile0.tianditu.com/services/sbsm0210
	全國15米衛(wèi)星影像 (ETM)	8-10級
	全國2.5米衛(wèi)星影像 (P5)	11-14級	http://tile0.tianditu.com/services/e11 http://tile0.tianditu.com/services/e12 http://tile0.tianditu.com/services/e13 http://tile0.tianditu.com/services/eastdawnall
	地級城市0.6米衛(wèi)星影像  (QuickBird、WorldView I、WorldView II)	15-18級	http://tile0.tianditu.com/services/sbsm1518
數(shù)字高程模型	全球90X90米數(shù)字高程模型		http://tile0.tianditu.com/services/J07098
地名地址	全球1:100萬地名地址		http://search.tianditu.com/wfs
	全國1:25萬地名地址
	全國車載導(dǎo)航地名地址

除地名地址數(shù)據(jù)使用OGC WFS協(xié)議發(fā)布外，其他數(shù)據(jù)全部采用基于OGC WMS-C協(xié)議的分級瓦片形式發(fā)布，工作原理類似于谷歌地圖和OSM（OpenStreetMap）。

類似谷歌地圖，“天地圖”為互聯(lián)網(wǎng)開發(fā)人員提供了二次開發(fā)API（武大吉奧開發(fā)的GeoGlobe二維地圖API）。

通過分析GeoGlobe API代碼，發(fā)現(xiàn)它源自O(shè)penlayers，大部分代碼除了把Openlayers換成GeoSurf外，沒有任何變化。不知道Openlayers項(xiàng)目組就此作何感想。
正因?yàn)槿绱耍覀兛梢詤⒖糘penLayers.Layer.TileCache和OpenLayers.Layer.XYZ類，編寫一個(gè)專用于讀取“天地圖”的TDTLayer類，使Openlayers能夠直接訪問“天地圖”的在線地圖數(shù)據(jù)。

“天地圖”采用256×256像素，png格式的地圖瓦片文件，讀取單個(gè)文件需要四個(gè)參數(shù)：T、X、Y、L
T=瓦片（Tile）名稱，X=瓦片橫向編碼，Y=瓦片縱向編碼，L=瓦片級別
這個(gè)是一個(gè)完整的請求示例：http://tile0.tianditu.com/DataServer?T=AB0512_Anno&X=50&Y=12&L=6

“天地圖”地理信息數(shù)據(jù)資源列表將地圖瓦片分為16級（L=2-18），其中L=2級比例尺最小，對應(yīng)全球地圖。
L=2級只有8個(gè)瓦片文件，分別是：
 X= 0 1 2 3 0 1 2 3
 Y= 0 0 0 0 1 1 1 1
L=3級有32個(gè)瓦片文件，分別是：
 X= 0-7
 Y= 0-3
L=4級有128個(gè)瓦片文件，分別是：
 X= 0-15
 Y= 0-7
其余各級以此類推，每級的瓦片文件數(shù)比前一級增加4倍，其中線劃地圖10級以上，衛(wèi)星地圖8級以上只提供中國境內(nèi)的數(shù)據(jù)，沒有覆蓋全球。

查看GeoGlobe API主代碼GeoSurfJSAPI.js文件（相當(dāng)于Openlayers.js），可以了解X(x_num)、Y(y_num)、L(level)的生成方法，偽代碼如下：
level=getLevelForResolution(map.getResolution()); //計(jì)算瓦片級別
coef=TopTileSize.w/Math.pow(2,level); //中間系數(shù)
x_num=this.pyramid.topTileFromX<this.pyramid.topTileToX?Math.round((bounds.left-this.pyramid.topTileFromX)/coef):Math.round((this.pyramid.topTileFromX-bounds.right)/coef);
y_num=this.pyramid.topTileFromY<this.pyramid.topTileToY?Math.round((bounds.bottom-this.pyramid.topTileFromY)/coef):Math.round((this.pyramid.topTileFromY-bounds.top)/coef);

根據(jù)當(dāng)前分辨率計(jì)算地圖瓦片級別

function getLevelForResolution(res){

var ratio=map.getMaxResolution()/res;

if(ratio<1)return 0;

for(var level=0;ratio/2>=1;)

{level++;ratio/=2;}

return level;

}



經(jīng)過簡單測試，“天地圖”和谷歌地圖在數(shù)據(jù)上差別不大，二次開發(fā)方面借助于強(qiáng)大的Openlayers地圖客戶端引擎不會(huì)弱于Google Map API，唯獨(dú)在速度上與谷歌地圖存在較大差距，特別是地圖放大到13級-18級時(shí)，延遲變得非常明顯，有時(shí)甚至無法顯示。

使用Firebug跟蹤運(yùn)行發(fā)現(xiàn)，大約1/3的地圖瓦片請求超時(shí)，導(dǎo)致客戶端讀取失敗。

“天地圖”目前還處于測試階段，希望相關(guān)單位繼續(xù)改進(jìn)和提升服務(wù)器端性能，快速穩(wěn)定的響應(yīng)大量客戶端發(fā)出的并發(fā)請求。

測試中發(fā)現(xiàn)，“天地圖”開放的地圖數(shù)據(jù)服務(wù)接口從tile0.tianditu.com一直到tile7.tianditu.com。依次ping 這8個(gè)服務(wù)接口，tile1到tile7的響應(yīng)速度相對較快。修改客戶端js代碼，將瓦片地圖請求平均發(fā)送給tile0到tile7 八個(gè)服務(wù)接口，可以有效加快地圖顯示速度。“天地圖”提供的GeoSurfJSAPI.js中已經(jīng)包含相關(guān)代碼，通過給Layer的mirrorUrl屬性賦值，可以均衡讀取指定的多個(gè)服務(wù)接口，代碼如下：
                        var layer3 = new GeoSurf.Layer.GlobeTile("siwei0608", "http://tile6.tianditu.com/services/siwei0608", {
                                transitionEffect: "resize",
                                topLevel: 13,
                                bottomLevel: 18,
                                maxExtent: new GeoSurf.Bounds(100, 27, 110, 34),
                                mirrorUrls: [
                                    "http://tile1.tianditu.com/services/siwei0608",
                                    "http://tile2.tianditu.com/services/siwei0608",
                                    "http://tile3.tianditu.com/services/siwei0608",
                                    "http://tile4.tianditu.com/services/siwei0608",
                                    "http://tile5.tianditu.com/services/siwei0608",
                                    "http://tile6.tianditu.com/services/siwei0608"
                                ]
                            });

客戶端使用上述讀取策略后，即便放大到17-18級，整幅地圖也能夠完全顯示，速度有明顯的提升。


發(fā)布WFS矢量地圖

OGC WFS協(xié)議定義了地圖客戶端查詢和傳送矢量數(shù)據(jù)的方法，在查詢、分析、動(dòng)態(tài)繪圖等實(shí)際應(yīng)用中非常有用。MapServer支持OGC WFS 1.0.0和1.1.0規(guī)范。

重新定義一個(gè)Mapfile文件，命名為ext2.map，內(nèi)容如下：
MAP

  NAME "vector"
    SHAPEPATH "I://cn_data"
    
    FONTSET fonts.txt
    IMAGECOLOR 255 255 255
    IMAGETYPE agg

    SIZE 800 600
    STATUS ON
    UNITS DD
    EXTENT 115.275 39.2204 117.475 40.9462
   
    OUTPUTFORMAT
        NAME agg
        DRIVER AGG/PNG
        IMAGEMODE RGB
        FORMATOPTION "INTERLACE=false"
        MIMETYPE "image/png"
    END

    PROJECTION
        "init=epsg:4326"
    END

    WEB
        METADATA
            "wms_title"                       "road wms"
            "wfs_title"                       "road wfs"
            "wms_onlineresource"              "http://192.98.151.23/cgi-bin/mapserv.exe?"  #mapserver服務(wù)器的url
            "wms_srs"                         "EPSG:4326"   #地圖坐標(biāo)系        
        END
    END

    LAYER
        NAME "road"
        METADATA
            "wms_title"                       "road"
            "wfs_title"                       "road"
            "wms_srs"                         "EPSG:4326"  #圖層坐標(biāo)系
            "gml_include_items"             "all"
            "gml_featureid"                 "id" #必須指定id
        END
        STATUS ON
        DATA "roa_4m.shp"
        TYPE line
        DUMP TRUE
        CLASS
            STYLE
                COLOR "#00FF00"
            END
        END
    END

END

該文件中有兩組METADATA標(biāo)簽，是WFS（WMS） Server所需要的，分別是MAP的METADATA標(biāo)簽和LAYER的METADATA標(biāo)簽。
前者是針對整個(gè)地圖的全局定義，后者是每個(gè)圖層的元數(shù)據(jù)定義。

保存Mapfile文件，打開瀏覽器進(jìn)行測試
http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&SERVICE=WFS&VERSION=1.0.0&REQUEST=GetCapabilities
正常情況下，可以看到以下返回信息
<WFS_Capabilities version="1.0.0" updateSequence="0" xsi:schemaLocation="http://www.opengis.net/wfs http://schemas.opengis.net/wfs/1.0.0/WFS-capabilities.xsd">
<!--
 MapServer version 5.2.1 OUTPUT=GIF OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP OUTPUT=PDF OUTPUT=SWF OUTPUT=SVG SUPPORTS=PROJ SUPPORTS=AGG SUPPORTS=FREETYPE SUPPORTS=ICONV SUPPORTS=FRIBIDI SUPPORTS=WMS_SERVER SUPPORTS=WMS_CLIENT SUPPORTS=WFS_SERVER SUPPORTS=WFS_CLIENT SUPPORTS=WCS_SERVER SUPPORTS=SOS_SERVER SUPPORTS=FASTCGI SUPPORTS=THREADS SUPPORTS=GEOS SUPPORTS=RGBA_PNG INPUT=JPEG INPUT=POSTGIS INPUT=ORACLESPATIAL INPUT=OGR INPUT=GDAL INPUT=SHAPEFILE
-->
<Service>
<Name>MapServer WFS</Name>
<Title>road wfs</Title>
<OnlineResource>
http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&
</OnlineResource>
</Service>
<Capability>
<Request>
<GetCapabilities>
<DCPType>
<HTTP>
<Get onlineResource="http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&"/>
</HTTP>
</DCPType>
<DCPType>
<HTTP>
<Post onlineResource="http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&"/>
</HTTP>
</DCPType>
</GetCapabilities>
<DescribeFeatureType>
<SchemaDescriptionLanguage>
<XMLSCHEMA/>
</SchemaDescriptionLanguage>
<DCPType>
<HTTP>
<Get onlineResource="http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&"/>
</HTTP>
</DCPType>
<DCPType>
<HTTP>
<Post onlineResource="http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&"/>
</HTTP>
</DCPType>
</DescribeFeatureType>
<GetFeature>
<ResultFormat>
<GML2/>
</ResultFormat>
<DCPType>
<HTTP>
<Get onlineResource="http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&"/>
</HTTP>
</DCPType>
<DCPType>
<HTTP>
<Post onlineResource="http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&"/>
</HTTP>
</DCPType>
</GetFeature>
</Request>
</Capability>
<FeatureTypeList>
<Operations>
<Query/>
</Operations>
<FeatureType>
<Name>road</Name>
<Title>road</Title>
<SRS>EPSG:4326</SRS>
<LatLongBoundingBox minx="80.3869" miny="18.2823" maxx="132.515" maxy="49.6272"/>
</FeatureType>
</FeatureTypeList>
<ogc:Filter_Capabilities>
<ogc:Spatial_Capabilities>
<ogc:Spatial_Operators>
<ogc:Equals/>
<ogc:Disjoint/>
<ogc:Touches/>
<ogc:Within/>
<ogc:Overlaps/>
<ogc:Crosses/>
<ogc:Intersect/>
<ogc:Contains/>
<ogc:DWithin/>
<ogc:BBOX/>
</ogc:Spatial_Operators>
</ogc:Spatial_Capabilities>
<ogc:Scalar_Capabilities>
<ogc:Logical_Operators/>
<ogc:Comparison_Operators>
<ogc:Simple_Comparisons/>
<ogc:Like/>
<ogc:Between/>
</ogc:Comparison_Operators>
</ogc:Scalar_Capabilities>
</ogc:Filter_Capabilities>
</WFS_Capabilities>

在OpenLayers中加載WFS圖層

OpenLayers是一個(gè)功能強(qiáng)大的Web地圖客戶端引擎。

接下來，我們利用OpenLayers的OpenLayers.Protocol.WFS類，顯示剛才發(fā)布的WFS圖層，代碼如下

       var protocol = OpenLayers.Protocol.WFS({
                    url: "http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&", //mapserver地圖服務(wù)器的url，加上mapfi了文件的路徑
                    featureType: "road", //layer的名稱
                    srsName: "EPSG:4326", //layer的坐標(biāo)系
                    geometryName: "msGeometry", //geometry字段的名稱
                    featurePrefix: "ms"
                });

以下是全部javascript代碼：
        window.onload = function() {
                var map = new OpenLayers.Map('mapdiv', {
                    projection: "EPSG:4326",
                    units: "degree"
                });
                
                var roads = new OpenLayers.Layer.WMS("road", "http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&", {
                    layers: 'road',
                    transparent: 'true',
                    format: 'image/png'
                }, {
                    isBaseLayer: false,
                    visibility: true,
                    buffer: 0
                });
                
                
                var empty = new OpenLayers.Layer("empty", {
                    isBaseLayer: true
                });
                
                var select = new OpenLayers.Layer.Vector("Selection", {
                    styleMap: new OpenLayers.Style(OpenLayers.Feature.Vector.style["select"]),
                    displayInLayerSwitcher: false
                });
                
                var hover = new OpenLayers.Layer.Vector("Hover", {
                    displayInLayerSwitcher: false
                });
                
                map.addLayers([roads, hover, select, empty]);
                
                var protocol = OpenLayers.Protocol.WFS({
                    url: "http://192.98.151.23/cgi-bin/mapserv.exe?map=I:/cn_data/ext2.map&",
                    featureType: "road",
                    srsName: "EPSG:4326",
                    geometryName: "msGeometry",
                    featurePrefix: "ms"
                });
                
                var control = new OpenLayers.Control.GetFeature({
                    protocol: protocol,
                    box: true,
                    hover: true,
                    multipleKey: "shiftKey",
                    toggleKey: "ctrlKey"
                });
                
                control.events.register("featureselected", this, function(e){
                    select.addFeatures([e.feature]);
                });
                control.events.register("featureunselected", this, function(e){
                    select.removeFeatures([e.feature]);
                });
                control.events.register("hoverfeature", this, function(e){
                    hover.addFeatures([e.feature]);
                });
                
                control.events.register("outfeature", this, function(e){
                    hover.removeFeatures([e.feature]);
                });
                
                map.addControl(control);
                control.activate();
                
                map.addControl(new OpenLayers.Control.LayerSwitcher());
                map.addControl(new OpenLayers.Control.MousePosition());
                
                if (!map.getCenter()) {
                    map.zoomToMaxExtent();
                }

            }

在瀏覽器中運(yùn)行html頁面，國道數(shù)據(jù)將以矢量方式傳送到客戶端，由openlayers動(dòng)態(tài)繪制，鼠標(biāo)移動(dòng)到道路上或者選中道路，道路將實(shí)時(shí)改變顏色，在Web上實(shí)現(xiàn)與傳統(tǒng)桌面GIS應(yīng)用類似的體驗(yàn)效果。

在今年的FOSS4G國際大會(huì)上，geoserver項(xiàng)目組發(fā)布了2.1beta1版本。
新版本增加了多項(xiàng)引人注目的功能，原文如下：

WMS Cascading

Something users have asked for since the addition of WMS support itself is cascading, the ability of GeoServer to proxy for another remote WMS server like MapServer or another GeoServer. This feature has many uses such as pulling in a remote base layer and overlaying local vector data onto it or securing a locally unsecured map server. Special thanks to the University of Perugia for sponsoring this feature.

Read more about WMS cascading.

Virtual Services

Anyone who has published a large number of layers or feature types with GeoServer has probably at some point been annoyed by the fact that every single layer is published by a single global service. WMS has the ability to group and nest layers but WFS and WCS have no such equivalent. Well now with virtual services one can create multiple service endpoints within a single physical geoserver instance.

Special thanks to Landgate for funding this work.

Read more about virtual services.

Layers from SQL

GeoServer has always been good at publishing a flat database table. But users often need to do more such as pre filter the data in a table, or join two tables together, or generate column values on the fly with a function. Before this feature the recommendation was to create a view. However views can be a maintenance burden and are at times problematic.

Now one can create a layer directly from an SQL query. And on top of that query definitions can be parameterized which allows one to create dynamic queries on the fly. These parameters can be restricted with regular expressions in order to prevent an SQL injection security hole.

Special thanks to Andrea for spending much of his personal time on this one. And also to OBIS who provided the funding for the parametric component of the work.

Read more about SQL layers.

WPS

With 2.1 and the arrival of WPS we welcome a new OGC service to the family. The Web Processing Service is an OGC service for performing geospatial analysis functions over the web. The specification is extensible in nature and allows for simple processes like buffering a geometry to more complex processes such as image processing.

Historically GeoServer has been focused primarily on data delivery without any tools for performing analysis of spatial data. WPS fills that gap making GeoServer a more compete solution for geospatial web services.

Thanks to Refractions Research for the initial contribution of the WPS module and to Andrea once again for taking personal time to bring WPS support to its current state.

Read more about WPS. Download the WPS extension now to try it out.

Unit of Measure

Support for units in SLD allows one to specify values in measurements other than pixels such as feet or meters. This adds a very powerful capability to SLD that in many cases alleviates the need for multiple scale dependent rendering rules. This has the upside of greatly simplifying complex SLD documents.

Special thanks to Milton Jonathan who did the initial GeoTools work to make unit of measure support possible and to Andrea for working with Milton to improve the initial patch. Note that this feature has also been backported to the stable 2.0.x branch. Thanks to SWECO and Malmö City of Sweden for sponsoring the backport.

Read more about UOM support.

DPI Scaling

By default GeoServer renders images at a resolution of 90 DPI. While this is acceptable for the standard screen it is not acceptable for print which requires a higher resolution. Now it is possible to supply a format option to a WMS request on the fly that controls the DPI setting.

Special thanks again to SWECO and to Malmö City of Sweden for sponsoring this work. Note also that this feature has also been backported to the stable 2.0.x branch.

Read more about DPI scaling.