com.vividsolutions.jts.io.WKBReader Maven / Gradle / Ivy
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/*
* The JTS Topology Suite is a collection of Java classes that
* implement the fundamental operations required to validate a given
* geo-spatial data set to a known topological specification.
*
* Copyright (C) 2001 Vivid Solutions
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* For more information, contact:
*
* Vivid Solutions
* Suite #1A
* 2328 Government Street
* Victoria BC V8T 5G5
* Canada
*
* (250)385-6040
* www.vividsolutions.com
*/
package com.vividsolutions.jts.io;
import java.io.IOException;
import com.vividsolutions.jts.geom.*;
/**
* Reads a {@link Geometry}from a byte stream in Well-Known Binary format.
* Supports use of an {@link InStream}, which allows easy use
* with arbitrary byte stream sources.
*
* This class reads the format describe in {@link 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.
*
* @see WKBWriter for a formal format specification
*/
public class WKBReader
{
/**
* Converts a hexadecimal string to a byte array.
* The hexadecimal digit symbols are case-insensitive.
*
* @param hex a string containing hex digits
* @return an array of bytes with the value of the hex string
*/
public static byte[] hexToBytes(String hex)
{
int byteLen = hex.length() / 2;
byte[] bytes = new byte[byteLen];
for (int i = 0; i < hex.length() / 2; i++) {
int i2 = 2 * i;
if (i2 + 1 > hex.length())
throw new IllegalArgumentException("Hex string has odd length");
int nib1 = hexToInt(hex.charAt(i2));
int nib0 = hexToInt(hex.charAt(i2 + 1));
byte b = (byte) ((nib1 << 4) + (byte) nib0);
bytes[i] = b;
}
return bytes;
}
private static int hexToInt(char hex)
{
int nib = Character.digit(hex, 16);
if (nib < 0)
throw new IllegalArgumentException("Invalid hex digit: '" + hex + "'");
return nib;
}
private static final String INVALID_GEOM_TYPE_MSG
= "Invalid geometry type encountered in ";
private GeometryFactory factory;
private CoordinateSequenceFactory csFactory;
private PrecisionModel precisionModel;
// default dimension - will be set on read
private int inputDimension = 2;
private boolean hasSRID = false;
private int SRID = 0;
/**
* true if structurally invalid input should be reported rather than repaired.
* At some point this could be made client-controllable.
*/
private boolean isStrict = false;
private ByteOrderDataInStream dis = new ByteOrderDataInStream();
private double[] ordValues;
public WKBReader() {
this(new GeometryFactory());
}
public WKBReader(GeometryFactory geometryFactory) {
this.factory = geometryFactory;
precisionModel = factory.getPrecisionModel();
csFactory = factory.getCoordinateSequenceFactory();
}
/**
* Reads a single {@link Geometry} in WKB format from a byte array.
*
* @param bytes the byte array to read from
* @return the geometry read
* @throws ParseException if the WKB is ill-formed
*/
public Geometry read(byte[] bytes) throws ParseException
{
// possibly reuse the ByteArrayInStream?
// don't throw IOExceptions, since we are not doing any I/O
try {
return read(new ByteArrayInStream(bytes));
}
catch (IOException ex) {
throw new RuntimeException("Unexpected IOException caught: " + ex.getMessage());
}
}
/**
* Reads a {@link Geometry} in binary WKB format from an {@link InStream}.
*
* @param is the stream to read from
* @return the Geometry read
* @throws IOException if the underlying stream creates an error
* @throws ParseException if the WKB is ill-formed
*/
public Geometry read(InStream is)
throws IOException, ParseException
{
dis.setInStream(is);
Geometry g = readGeometry();
return g;
}
private Geometry readGeometry()
throws IOException, ParseException
{
// determine byte order
byte byteOrderWKB = dis.readByte();
// always set byte order, since it may change from geometry to geometry
if(byteOrderWKB == WKBConstants.wkbNDR)
{
dis.setOrder(ByteOrderValues.LITTLE_ENDIAN);
}
else if(byteOrderWKB == WKBConstants.wkbXDR)
{
dis.setOrder(ByteOrderValues.BIG_ENDIAN);
}
else if(isStrict)
{
throw new ParseException("Unknown geometry byte order (not NDR or XDR): " + byteOrderWKB);
}
//if not strict and not XDR or NDR, then we just use the dis default set at the
//start of the geometry (if a multi-geometry). This allows WBKReader to work
//with Spatialite native BLOB WKB, as well as other WKB variants that might just
//specify endian-ness at the start of the multigeometry.
int typeInt = dis.readInt();
int geometryType = typeInt & 0xff;
// determine if Z values are present
boolean hasZ = (typeInt & 0x80000000) != 0;
inputDimension = hasZ ? 3 : 2;
// determine if SRIDs are present
hasSRID = (typeInt & 0x20000000) != 0;
int SRID = 0;
if (hasSRID) {
SRID = dis.readInt();
}
// only allocate ordValues buffer if necessary
if (ordValues == null || ordValues.length < inputDimension)
ordValues = new double[inputDimension];
Geometry geom = null;
switch (geometryType) {
case WKBConstants.wkbPoint :
geom = readPoint();
break;
case WKBConstants.wkbLineString :
geom = readLineString();
break;
case WKBConstants.wkbPolygon :
geom = readPolygon();
break;
case WKBConstants.wkbMultiPoint :
geom = readMultiPoint();
break;
case WKBConstants.wkbMultiLineString :
geom = readMultiLineString();
break;
case WKBConstants.wkbMultiPolygon :
geom = readMultiPolygon();
break;
case WKBConstants.wkbGeometryCollection :
geom = readGeometryCollection();
break;
default:
throw new ParseException("Unknown WKB type " + geometryType);
}
setSRID(geom, SRID);
return geom;
}
/**
* Sets the SRID, if it was specified in the WKB
*
* @param g the geometry to update
* @return the geometry with an updated SRID value, if required
*/
private Geometry setSRID(Geometry g, int SRID)
{
if (SRID != 0)
g.setSRID(SRID);
return g;
}
private Point readPoint() throws IOException
{
CoordinateSequence pts = readCoordinateSequence(1);
return factory.createPoint(pts);
}
private LineString readLineString() throws IOException
{
int size = dis.readInt();
CoordinateSequence pts = readCoordinateSequenceLineString(size);
return factory.createLineString(pts);
}
private LinearRing readLinearRing() throws IOException
{
int size = dis.readInt();
CoordinateSequence pts = readCoordinateSequenceRing(size);
return factory.createLinearRing(pts);
}
private Polygon readPolygon() throws IOException
{
int numRings = dis.readInt();
LinearRing[] holes = null;
if (numRings > 1)
holes = new LinearRing[numRings - 1];
LinearRing shell = readLinearRing();
for (int i = 0; i < numRings - 1; i++) {
holes[i] = readLinearRing();
}
return factory.createPolygon(shell, holes);
}
private MultiPoint readMultiPoint() throws IOException, ParseException
{
int numGeom = dis.readInt();
Point[] geoms = new Point[numGeom];
for (int i = 0; i < numGeom; i++) {
Geometry g = readGeometry();
if (! (g instanceof Point))
throw new ParseException(INVALID_GEOM_TYPE_MSG + "MultiPoint");
geoms[i] = (Point) g;
}
return factory.createMultiPoint(geoms);
}
private MultiLineString readMultiLineString() throws IOException, ParseException
{
int numGeom = dis.readInt();
LineString[] geoms = new LineString[numGeom];
for (int i = 0; i < numGeom; i++) {
Geometry g = readGeometry();
if (! (g instanceof LineString))
throw new ParseException(INVALID_GEOM_TYPE_MSG + "MultiLineString");
geoms[i] = (LineString) g;
}
return factory.createMultiLineString(geoms);
}
private MultiPolygon readMultiPolygon() throws IOException, ParseException
{
int numGeom = dis.readInt();
Polygon[] geoms = new Polygon[numGeom];
for (int i = 0; i < numGeom; i++) {
Geometry g = readGeometry();
if (! (g instanceof Polygon))
throw new ParseException(INVALID_GEOM_TYPE_MSG + "MultiPolygon");
geoms[i] = (Polygon) g;
}
return factory.createMultiPolygon(geoms);
}
private GeometryCollection readGeometryCollection() throws IOException, ParseException
{
int numGeom = dis.readInt();
Geometry[] geoms = new Geometry[numGeom];
for (int i = 0; i < numGeom; i++) {
geoms[i] = readGeometry();
}
return factory.createGeometryCollection(geoms);
}
private CoordinateSequence readCoordinateSequence(int size) throws IOException
{
CoordinateSequence seq = csFactory.create(size, inputDimension);
int targetDim = seq.getDimension();
if (targetDim > inputDimension)
targetDim = inputDimension;
for (int i = 0; i < size; i++) {
readCoordinate();
for (int j = 0; j < targetDim; j++) {
seq.setOrdinate(i, j, ordValues[j]);
}
}
return seq;
}
private CoordinateSequence readCoordinateSequenceLineString(int size) throws IOException
{
CoordinateSequence seq = readCoordinateSequence(size);
if (isStrict) return seq;
if (seq.size() == 0 || seq.size() >= 2) return seq;
return CoordinateSequences.extend(csFactory, seq, 2);
}
private CoordinateSequence readCoordinateSequenceRing(int size) throws IOException
{
CoordinateSequence seq = readCoordinateSequence(size);
if (isStrict) return seq;
if (CoordinateSequences.isRing(seq)) return seq;
return CoordinateSequences.ensureValidRing(csFactory, seq);
}
/**
* Reads a coordinate value with the specified dimensionality.
* Makes the X and Y ordinates precise according to the precision model
* in use.
*/
private void readCoordinate() throws IOException
{
for (int i = 0; i < inputDimension; i++) {
if (i <= 1) {
ordValues[i] = precisionModel.makePrecise(dis.readDouble());
}
else {
ordValues[i] = dis.readDouble();
}
}
}
}