Question

我正在尝试使用GeoTools过滤启用PostGIS的数据库中的要素表中的要素。

我的配置：

PostgreSQL 8.4
PostGIS 1.5
渗透0.40.1
OSMembrane build 845
GeoTools 2.7.4

设置

我通过按顺序执行这些sql脚本来设置启用postgis的数据库：

[PATH_TO_POSTGRESQL_8.4] /share/contrib/postgis-1.5/postgis.sql
[PATH_TO_POSTGRESQL_8.4] /share/contrib/postgis-1.5/spatial_ref_sys.sql
[PATH_TO_POSTGRESQL_8.4] /postgresql/8.4/contrib/hstore.sql
[PATH_TO_OSMOSIS_0_40_1 /脚本/ pgsnapshot_schema_0.6.sql

然后我导入一些使用OSMembrane从europe.osm中提取的.osm数据。

CREATE TABLE ways
(
  id bigint NOT NULL,
  "version" integer NOT NULL,
  user_id integer NOT NULL,
  tstamp timestamp without time zone NOT NULL,
  changeset_id bigint NOT NULL,
  tags hstore,
  nodes bigint[],
  CONSTRAINT pk_ways PRIMARY KEY (id)
)

特别是'tags'列包含我想用于过滤的键/值对。当尝试在SQL中按“natural = coastline”过滤行时，我得到〜550行。

SELECT tags FROM ways where tags @> 'natural => coastline'

Example result: '"source"=>"PGS", "natural"=>"coastline", "created_by"=>"almien_coastlines"'

使用GeoTools尝试使用GeoTools无法正常工作，因为此示例有望向您展示。

package getfeaturesapplication;

import java.util.HashMap;
import java.util.Map;
import org.geotools.data.DataStore;
import org.geotools.data.DataStoreFinder;
import org.geotools.data.postgis.PostgisNGDataStoreFactory;
import org.geotools.data.simple.SimpleFeatureSource;

public class GetFeaturesApplication {

    public static void main(String[] args) {
        try {
            Map<String, Object> parameters = new HashMap<String, Object>();

            parameters.put(PostgisNGDataStoreFactory.DBTYPE.key, "postgis");
            parameters.put(PostgisNGDataStoreFactory.HOST.key, "localhost");
            parameters.put(PostgisNGDataStoreFactory.PORT.key, new Integer(5432));
            parameters.put(PostgisNGDataStoreFactory.DATABASE.key, "postgis");
            parameters.put(PostgisNGDataStoreFactory.SCHEMA.key, "public");
            parameters.put(PostgisNGDataStoreFactory.USER.key, "osm");
            parameters.put(PostgisNGDataStoreFactory.PASSWD.key, "osm");

            DataStore dataStore = DataStoreFinder.getDataStore(parameters);

            String featureName = "ways";
            SimpleFeatureSource featureSource = dataStore.getFeatureSource(featureName); //=> WARNINGS

            SimpleFeatureCollection features1 = featureSource.getFeatures();
            System.out.println("Feature count: " + features1.size()); //406391

            FilterFactory2 filterFactory = CommonFactoryFinder.getFilterFactory2(null);
            Filter filter = filterFactory.equals(filterFactory.literal("natural"), filterFactory.literal("coastline"));
            SimpleFeatureCollection features2 = featureSource.getFeatures(filter);
            System.out.println("Features found after filtering: " + !features2.isEmpty()); //SEEMS TO BE ALWAYS EMPTY
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}

运行此应用程序时，我得到：

31.01.2012 15:27:49 org.geotools.jdbc.JDBCFeatureSource buildFeatureType
WARNING: Could not find mapping for 'tags', ignoring the column and setting the feature type read only
31.01.2012 15:27:49 org.geotools.jdbc.JDBCFeatureSource buildFeatureType
WARNING: Could not find mapping for 'nodes', ignoring the column and setting the feature type read only
Feature count: 406391
Features found after filtering: false

hstore和bigint []列存在问题，还是我滥用GeoTools？也许，你可以给我一些提示。

Answer 1

虽然我从来没有能够让geoServer直接使用hstore（在基于SQL视图的层中），但我能够向数据库添加辅助函数，这样就可以显示内容。功能是

CREATE OR REPLACE FUNCTION hstore_to_text(h hstore)
  RETURNS text AS
$BODY$
DECLARE
  txt text;
BEGIN
   txt := cast(h as text);

   return txt;
END  $BODY$
  LANGUAGE 'plpgsql' volatile
  COST 1;
ALTER FUNCTION hstore_to_text(hstore)
  OWNER TO postgres;

然后，您可以使用类似

的内容转换查询中的hstore

选择id，hstore_to_text（hst_var），来自mytable的mygeom

而FWIW - 直接在查询中执行演员表（或其他任何变体 - 不通过函数）都不起作用。

Answer 2

我不确定GeoTools PostGIS阅读器是否支持hstore列。 Here are some notes我在PostGIS中导入OSM数据。我的目标是在GeoServer中显示它们，它使用GeoTools数据存储来读取它。我按标签分割数据以使其正常工作。

如何使用GeoTools从hstore列过滤数据？

2 个答案: