deegree#849 - writing of single features (PR285)

deegree-core/deegree-core-base/src/main/java/org/deegree/geojson/GeoJsonSingleFeatureWriter.java

@@ -0,0 +1,52 @@
+package org.deegree.geojson;
+
+import org.deegree.cs.exceptions.TransformationException;
+import org.deegree.cs.exceptions.UnknownCRSException;
+import org.deegree.feature.Feature;
+
+import java.io.IOException;
+
+/**
+ * Writer for GeoJSON documents with single features.
+ *
+ * @author <a href="mailto:goltz@lat-lon.de">Lyn Goltz </a>
+ */
+public interface GeoJsonSingleFeatureWriter {
+
+    /**
+     * Starts a single feature.
+     * <p>
+     * To finish the feature call endSingleFeature
+     *
+     * @throws IOException
+     *                 if GeoJSON could no be written
+     */
+    void startSingleFeature()
+                    throws IOException;
+
+    /**
+     * Ends the written feature.
+     * <p>
+     * Ensure that startSingleFeature was called before.
+     *
+     * @throws IOException
+     *                 if GeoJSON could no be written
+     */
+    void endSingleFeature()
+                    throws IOException;
+
+    /**
+     * Writes a new, single feature.
+     *
+     * @param feature
+     *                 the feature to write, never <code>null</code>
+     * @throws IOException
+     *                 if GeoJSON could no be written
+     * @throws TransformationException
+     *                 if a geometry to export cannot be transformed to CRS:84
+     * @throws UnknownCRSException
+     *                 if the CRS of the geometry is not supported
+     */
+    void writeSingleFeature( Feature feature )
+                    throws IOException, UnknownCRSException, TransformationException;
+}

deegree-core/deegree-core-base/src/main/java/org/deegree/geojson/GeoJsonWriter.java

@@ -40,7 +40,7 @@
  *
  * @author <a href="mailto:goltz@lat-lon.de">Lyn Goltz </a>
  */
-public class GeoJsonWriter extends JsonWriter implements GeoJsonFeatureWriter {
+public class GeoJsonWriter extends JsonWriter implements GeoJsonFeatureWriter, GeoJsonSingleFeatureWriter {
 
     private static final Logger LOG = LoggerFactory.getLogger( GeoJsonWriter.class );
 
@@ -90,6 +90,20 @@ public void endFeatureCollection()
         endObject();
     }
 
+    @Override
+    public void startSingleFeature()
+                    throws IOException {
+        isStarted = true;
+        beginObject();
+        name( "type" ).value( "Feature" );
+    }
+
+    @Override
+    public void endSingleFeature()
+                    throws IOException {
+        endObject();
+    }
+
     @Override
     public void write( Feature feature )
                             throws IOException, TransformationException, UnknownCRSException {
@@ -100,13 +114,18 @@ public void write( Feature feature )
             name( "features" ).beginArray();
             isStarted = true;
         }
-        beginObject();
-        name( "type" ).value( "Feature" );
+        startSingleFeature();
+        writeSingleFeature( feature );
+        endSingleFeature();
+    }
+
+    @Override
+    public void writeSingleFeature( Feature feature )
+                    throws IOException, UnknownCRSException, TransformationException {
         name( "id" ).value( feature.getId() );
         writeGeometry( feature );
         writeProperties( feature );
         writeCrs();
-        endObject();
     }
 
     private void writeGeometry( Feature feature )

deegree-core/deegree-core-base/src/test/java/org/deegree/geojson/GeoJsonFeatureWriterTest.java

@@ -59,6 +59,41 @@ public void testWrite()
 
     }
 
+    @Test
+    public void testWrite_SingleFeature()
+                    throws Exception {
+        StringWriter featureAsJson = new StringWriter();
+        GeoJsonWriter geoJsonFeatureWriter = new GeoJsonWriter( featureAsJson, null );
+        Feature cadastralZoning = parseFeature( "CadastralZoningWithPrimitiveArray.gml" );
+
+        geoJsonFeatureWriter.startSingleFeature();
+        geoJsonFeatureWriter.writeSingleFeature( cadastralZoning );
+        geoJsonFeatureWriter.endSingleFeature();
+
+        String featureCollection = featureAsJson.toString();
+
+        assertThat( featureCollection, JsonPathMatchers.isJson() );
+        assertThat( featureCollection, hasJsonPath( "$.type", is( "Feature" ) ) );
+        assertThat( featureCollection, hasNoJsonPath( "$.srsName" ) );
+        assertThat( featureCollection, hasJsonPath( "$.id", is( "CP_CADASTRALZONING_Bundesland_02" ) ) );
+        assertThat( featureCollection, hasJsonPath( "$.geometry" ) );
+        assertThat( featureCollection, hasJsonPath( "$.properties.label", hasItem( "01" ) ) );
+        assertThat( featureCollection, hasJsonPath( "$.properties.label", hasItem( "02" ) ) );
+        assertThat( featureCollection,
+                    hasJsonPath( "$.properties.originalMapScaleDenominator", is( 10 ) ) );
+        assertThat( featureCollection,
+                    hasJsonPath( "$.properties.beginLifespanVersion", is( "2009-12-15T08:04:54Z" ) ) );
+        assertThat( featureCollection, hasJsonPath( "$.properties.estimatedAccuracy.uom", is( "m" ) ) );
+        assertThat( featureCollection, hasJsonPath( "$.properties.inspireId.Identifier.localId",
+                                                    is( "urn:adv:oid:DEHHALKA10000005" ) ) );
+        assertThat( featureCollection,
+                    hasJsonPath( "$.properties.name.GeographicalName.spelling.SpellingOfName.text",
+                                 is( "Hamburg" ) ) );
+        assertThat( featureCollection, hasJsonPath( "$.properties.levelName.LocalisedCharacterString.value",
+                                                    is( "Bundesland" ) ) );
+    }
+
+
     @Test
     public void testWriteWithCrs()
                             throws Exception {