Package org.locationtech.jts.io

Class WKBReader

java.lang.Object

org.locationtech.jts.io.WKBReader

public class WKBReader
extends Object

Reads a Geometryfrom a byte stream in Well-Known Binary format. Supports use of an InStream, which allows easy use with arbitrary byte stream sources.

This class reads the format describe in WKBWriter. It also partially handles the Extended WKB format used by PostGIS, by parsing and storing SRID values. The reader repairs structurally-invalid input (specifically, LineStrings and LinearRings which contain too few points have vertices added, and non-closed rings are closed).

This class is designed to support reuse of a single instance to read multiple geometries. This class is not thread-safe; each thread should create its own instance.

As of version 1.15, the reader can read geometries following OGC 06-103r4 speification used by Spatialite/Geopackage.

The difference between PostGIS EWKB format and the new OGC specification is that Z and M coordinates are detected with a bit mask on the higher byte in the former case (0x80 for Z and 0x40 for M) while new OGC specification use specif int ranges for 2D gemetries, Z geometries (2D code+1000), M geometries (2D code+2000) and ZM geometries (2D code+3000).

Note that the WKBWriter is not changed and still write PostGIS WKB geometries

See Also:

• for a formal format specification

Field Summary

Fields

Modifier and Type	Field	Description
private CoordinateSequenceFactory	csFactory
private ByteOrderDataInStream	dis
private GeometryFactory	factory
private boolean	hasSRID
private int	inputDimension
private static final String	INVALID_GEOM_TYPE_MSG
private boolean	isStrict	true if structurally invalid input should be reported rather than repaired.
private double[]	ordValues
private PrecisionModel	precisionModel
private int	SRID

Constructor Summary

Constructors

Constructor	Description
WKBReader()
WKBReader(GeometryFactory geometryFactory)

Method Summary

Modifier and Type	Method	Description
static byte[]	hexToBytes(String hex)	Converts a hexadecimal string to a byte array.
private static int	hexToInt(char hex)
Geometry	read(byte[] bytes)	Reads a single Geometry in WKB format from a byte array.
Geometry	read(InStream is)	Reads a Geometry in binary WKB format from an InStream.
private void	readCoordinate()	Reads a coordinate value with the specified dimensionality.
private CoordinateSequence	readCoordinateSequence(int size)
private CoordinateSequence	readCoordinateSequenceLineString(int size)
private CoordinateSequence	readCoordinateSequenceRing(int size)
private Geometry	readGeometry()
private GeometryCollection	readGeometryCollection()
private LinearRing	readLinearRing()
private LineString	readLineString()
private MultiLineString	readMultiLineString()
private MultiPoint	readMultiPoint()
private MultiPolygon	readMultiPolygon()
private Point	readPoint()
private Polygon	readPolygon()
private Geometry	setSRID(Geometry g, int SRID)	Sets the SRID, if it was specified in the WKB

Methods inherited from class java.lang.Object

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

Field Details

INVALID_GEOM_TYPE_MSG

private static final String INVALID_GEOM_TYPE_MSG

See Also:

• Constant Field Values

factory

private GeometryFactory factory

csFactory

private CoordinateSequenceFactory csFactory

precisionModel

private PrecisionModel precisionModel

inputDimension

private int inputDimension

hasSRID

private boolean hasSRID

SRID

private int SRID

isStrict

private boolean isStrict

true if structurally invalid input should be reported rather than repaired. At some point this could be made client-controllable.

dis

private ByteOrderDataInStream dis

ordValues

private double[] ordValues

Constructor Details

WKBReader

public WKBReader()

WKBReader

public WKBReader(GeometryFactory geometryFactory)

Method Details

hexToBytes

public static byte[] hexToBytes(String hex)

Converts a hexadecimal string to a byte array. The hexadecimal digit symbols are case-insensitive.

Parameters:

hex - a string containing hex digits

Returns:

an array of bytes with the value of the hex string

hexToInt

private static int hexToInt(char hex)

read

public Geometry read(byte[] bytes)
              throws ParseException

Reads a single Geometry in WKB format from a byte array.

Parameters:

bytes - the byte array to read from

Returns:

the geometry read

Throws:

ParseException - if the WKB is ill-formed

read

public Geometry read(InStream is)
              throws IOException,
ParseException

Reads a Geometry in binary WKB format from an InStream.

Parameters:

is - the stream to read from

Returns:

the Geometry read

Throws:

IOException - if the underlying stream creates an error

ParseException - if the WKB is ill-formed

readGeometry

private Geometry readGeometry()
                       throws IOException,
ParseException

Throws:

IOException

ParseException

setSRID

private Geometry setSRID(Geometry g,
 int SRID)

Sets the SRID, if it was specified in the WKB

Parameters:

g - the geometry to update

Returns:

the geometry with an updated SRID value, if required

readPoint

private Point readPoint()
                 throws IOException

Throws:

IOException

readLineString

private LineString readLineString()
                           throws IOException

Throws:

IOException

readLinearRing

private LinearRing readLinearRing()
                           throws IOException

Throws:

IOException

readPolygon

private Polygon readPolygon()
                     throws IOException

Throws:

IOException

readMultiPoint

private MultiPoint readMultiPoint()
                           throws IOException,
ParseException

Throws:

IOException

ParseException

readMultiLineString

private MultiLineString readMultiLineString()
                                     throws IOException,
ParseException

Throws:

IOException

ParseException

readMultiPolygon

private MultiPolygon readMultiPolygon()
                               throws IOException,
ParseException

Throws:

IOException

ParseException

readGeometryCollection

private GeometryCollection readGeometryCollection()
                                           throws IOException,
ParseException

Throws:

IOException

ParseException

readCoordinateSequence

private CoordinateSequence readCoordinateSequence(int size)
                                           throws IOException

Throws:

IOException

readCoordinateSequenceLineString

private CoordinateSequence readCoordinateSequenceLineString(int size)
                                                     throws IOException

Throws:

IOException

readCoordinateSequenceRing

private CoordinateSequence readCoordinateSequenceRing(int size)
                                               throws IOException

Throws:

IOException

readCoordinate

private void readCoordinate()
                     throws IOException

Reads a coordinate value with the specified dimensionality. Makes the X and Y ordinates precise according to the precision model in use.

Throws:

IOException