eu.slipo.athenarc.triplegeo.tools

Class RdfToGeoJson

java.lang.Object

eu.slipo.athenarc.triplegeo.tools.RdfToGeoJson

All Implemented Interfaces:

ReverseConverter

public class RdfToGeoJson
extends java.lang.Object
implements ReverseConverter

Main entry point of the utility for reconverting triples from a RDF graph into a GeoJson file. LIMITATIONS: There are certain limitations of the GeoJson format: - According to the latest GeoJSON specification (RFC7946), the CRS must be WGS84(lat/long). - In case that there are mixed geometry types in input geometries (e.g., some are points while others are polygons), these are retained in the GeoJson file.

Version:

2.0

Author:

Kostas Patroumpas

Field Summary

Fields

Modifier and Type	Field and Description
(package private) java.lang.String	attrGeom
private static org.opengis.referencing.crs.CRSAuthorityFactory	crsFactory
private ReverseConfiguration	currentConfig
private java.lang.String	encoding
(package private) org.geotools.feature.simple.SimpleFeatureBuilder	featureBuilder
(package private) org.geotools.geojson.feature.FeatureJSON	fJSON
(package private) java.lang.String	geomType
(package private) Assistant	myAssistant
(package private) int	numRecs
private java.lang.String	outputFile
(package private) com.vividsolutions.jts.io.WKTReader	reader
private org.opengis.referencing.operation.MathTransform	reproject
(package private) int	sourceSRID
(package private) int	targetSRID
(package private) java.lang.String	typeName
private java.io.BufferedWriter	writer

Constructor Summary

Constructors

Constructor and Description
RdfToGeoJson(ReverseConfiguration config, java.lang.String outFile, int sourceSRID, int targetSRID) Constructor for the reverse transformation process from RDF to GeoJson.

Method Summary

Modifier and Type	Method and Description
void	close() Closes output file, once all results have been written.
boolean	createSchema(java.util.List<java.lang.String> attrList, org.apache.jena.query.QuerySolution sol) Determine schema with all attribute names and their data types.
com.vividsolutions.jts.geom.Geometry	getGeometry(java.lang.String g) Cleans up geometry literals and generates its internal representation.
java.lang.String	getGeometrySpec(org.apache.jena.rdf.model.Literal g) Identifies SRID (EPSG code) and geometry type from a WKT literal.
java.lang.String	getGeometrySpec(java.lang.String g) Identifies SRID (EPSG code) and geometry type from a WKT string.
java.lang.Integer	store(java.util.List<java.lang.String> attrList, java.util.List<java.util.List<java.lang.String>> results) Creates a feature collection from current batch of records and writes them into the output GeoJson file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

myAssistant

Assistant myAssistant

reproject

private org.opengis.referencing.operation.MathTransform reproject

reader

com.vividsolutions.jts.io.WKTReader reader

sourceSRID

int sourceSRID

targetSRID

int targetSRID

currentConfig

private ReverseConfiguration currentConfig

outputFile

private java.lang.String outputFile

encoding

private java.lang.String encoding

writer

private java.io.BufferedWriter writer

fJSON

org.geotools.geojson.feature.FeatureJSON fJSON

featureBuilder

org.geotools.feature.simple.SimpleFeatureBuilder featureBuilder

geomType

java.lang.String geomType

typeName

java.lang.String typeName

attrGeom

java.lang.String attrGeom

numRecs

int numRecs

crsFactory

private static final org.opengis.referencing.crs.CRSAuthorityFactory crsFactory

Constructor Detail

RdfToGeoJson

public RdfToGeoJson(ReverseConfiguration config,
                    java.lang.String outFile,
                    int sourceSRID,
                    int targetSRID)

Constructor for the reverse transformation process from RDF to GeoJson.

Parameters:

config - Parameters for Reverse Transformation.

outFile - Path to the output GeoJson file.

sourceSRID - Spatial reference system (EPSG code) of geometries in the input RDF triples

targetSRID - Spatial reference system (EPSG code) of the output GeoJson file

Method Detail

close

public void close()

Closes output file, once all results have been written.

Specified by:

close in interface ReverseConverter

createSchema

public boolean createSchema(java.util.List<java.lang.String> attrList,
                            org.apache.jena.query.QuerySolution sol)

Determine schema with all attribute names and their data types.

Specified by:

createSchema in interface ReverseConverter

Parameters:

attrList - List of attribute names. Attributes in the schema will be created in the same order as specified in the SELECT query that fetches results from the RDF graph.

sol - A single result (record) from a SELECT query in SPARQL.

Returns:

True if attribute schema has been created successfully; otherwise, False.

getGeometry

public com.vividsolutions.jts.geom.Geometry getGeometry(java.lang.String g)

Cleans up geometry literals and generates its internal representation.

Specified by:

getGeometry in interface ReverseConverter

Parameters:

g - A geometry WKT string.

Returns:

The internal representation of the geometry.

store

public java.lang.Integer store(java.util.List<java.lang.String> attrList,
                               java.util.List<java.util.List<java.lang.String>> results)

Creates a feature collection from current batch of records and writes them into the output GeoJson file.

Specified by:

store in interface ReverseConverter

Parameters:

attrList - List of attribute names.

results - Collection of records in the current batch.

Returns:

The number of records resulted in the current batch.

getGeometrySpec

public java.lang.String getGeometrySpec(org.apache.jena.rdf.model.Literal g)

Description copied from interface: ReverseConverter

Identifies SRID (EPSG code) and geometry type from a WKT literal. Applicable in reverse transformation into shapefile format.

Specified by:

getGeometrySpec in interface ReverseConverter

Parameters:

g - A geometry WKT literal.

Returns:

A string that concatenates the geometry type and the SRID of the given WKT literal.

getGeometrySpec

public java.lang.String getGeometrySpec(java.lang.String g)

Description copied from interface: ReverseConverter

Identifies SRID (EPSG code) and geometry type from a WKT string. Applicable in reverse transformation into CSV format.

Specified by:

getGeometrySpec in interface ReverseConverter

Parameters:

g - A geometry WKT string.

Returns:

An extended WKT (EWKT) representation, which includes the SRID.