Android WMS地图库

Question

目前我正在使用 Geoserver 中的地图。我想在 android 中以 WMS 格式显示地图。我见过 openscales、mapsforge、osm-droid。哪些 android 地图库最适合处理 WMS、WFS 图层？它们的优缺点是什么？

Answer 1

我不为 WMS 使用特定的库，因为我不喜欢它们（对于特定的情况来说太复杂了，在我的情况下是非标准情况），所以我创建了我的 class 来管理它.例如，在地图上显示 WMS 只是简单地覆盖 URLTileProvider：

/*
 * Copyright [2015] Nicola Dorigatti
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 *    limitations under the License.
 */

package it.dorigatti.android.editing.wms;

import com.google.android.gms.maps.model.UrlTileProvider;

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.nio.charset.Charset;

public abstract class WMSTileProvider extends UrlTileProvider {

    // Web Mercator n/w corner of the map.
    private static final double[] TILE_ORIGIN = { -20037508.34789244, 20037508.34789244 };
    // array indexes for that data
    private static final int ORIG_X = 0;
    private static final int ORIG_Y = 1; // "

    // Size of square world map in meters, using WebMerc projection.
    private static final double MAP_SIZE = 20037508.34789244 * 2;

    // array indexes for array to hold bounding boxes.
    protected static final int MINX = 0;
    protected static final int MAXX = 1;
    protected static final int MINY = 2;
    protected static final int MAXY = 3;

    // cql filters
    private String cqlString = "";

    // Construct with tile size in pixels, normally 256, see parent class.
    public WMSTileProvider(int x, int y) {
        super(x, y);
    }

    @SuppressWarnings("deprecation")
    protected String getCql() {
        try {
            return URLEncoder.encode(cqlString, Charset.defaultCharset().name());
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            return URLEncoder.encode(cqlString);
        }
    }

    public void setCql(String c) {
        cqlString = c;
    }

    // Return a web Mercator bounding box given tile x/y indexes and a zoom
    // level.
    protected double[] getBoundingBox(int x, int y, int zoom) {
        double tileSize = MAP_SIZE / Math.pow(2, zoom);
        double minx = TILE_ORIGIN[ORIG_X] + x * tileSize;
        double maxx = TILE_ORIGIN[ORIG_X] + (x + 1) * tileSize;
        double miny = TILE_ORIGIN[ORIG_Y] - (y + 1) * tileSize;
        double maxy = TILE_ORIGIN[ORIG_Y] - y * tileSize;

        double[] bbox = new double[4];
        bbox[MINX] = minx;
        bbox[MINY] = miny;
        bbox[MAXX] = maxx;
        bbox[MAXY] = maxy;

        return bbox;
    }

}

他们将图层管理为：

/*
 * Copyright [2015] Nicola Dorigatti
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 *    limitations under the License.
 */

package it.dorigatti.android.editing.wms;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.Locale;

import it.dorigatti.android.editing.dto.WMSLayerInfo;

public class TileProviderFactory {

    public static WMSTileProvider getWMSTileProviderByName(String layerName) {
        final String OSGEO_WMS = "YOURGEOSERVER/gwc/service/wms/?"
                + "LAYERS=" + layerName
                + "&FORMAT=image/png8&"
                + "PROJECTION=EPSG:3857&"
                + "TILEORIGIN=lon=-20037508.34,lat=-20037508.34&"
                + "TILESIZE=w=256,h=256"
                + "&MAXEXTENT=-20037508.34,-20037508.34,20037508.34,20037508.34&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&SRS=EPSG:3857"
                + "&BBOX=%f,%f,%f,%f&WIDTH=256&HEIGHT=256";

        return new WMSTileProvider(256, 256) {

            @Override
            public synchronized URL getTileUrl(int x, int y, int zoom) {
                final double[] bbox = getBoundingBox(x, y, zoom);
                String s = String.format(Locale.US, OSGEO_WMS, bbox[MINX], bbox[MINY], bbox[MAXX], bbox[MAXY]);
                try {
                    return new URL(s);
                } catch (MalformedURLException e) {
                    throw new AssertionError(e);
                }
            }
        };
    }

}

对于 WFS 服务，我开发了一个小型库，它使用 GeoJSON 作为数据 download/upload。 XML 不适合 android 并且 WFS 太宽无法支持所有内容，所以我只是根据需要实现了它。请注意，geoserver 在某些情况下与 WFS v2 存在一些问题，我不得不切换到 WFS 1.1。

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