com.revolsys.jts.io

Class WKBReader

java.lang.Object

com.revolsys.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.

See Also:

for a formal format specification

Constructor Summary

Constructors

Constructor and Description
WKBReader()
WKBReader(GeometryFactory geometryFactory)

Method Summary

Methods

Modifier and Type	Method and Description
static LineString	createClosedRing(LineString seq, int size)
static LineString	ensureValidRing(LineString seq) Ensures that a LineString forms a valid ring, returning a new closed sequence of the correct length if required.
static LineString	extend(LineString seq, int size)
static byte[]	hexToBytes(String hex) Converts a hexadecimal string to a byte array.
static boolean	isEqual(LineString cs1, LineString cs2) Tests whether two LineStrings are equal.
static boolean	isRing(LineString seq) Tests whether a LineString forms a valid LinearRing, by checking the sequence length and closure (whether the first and last points are identical in 2D).
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.

Methods inherited from class java.lang.Object

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

Constructor Detail

WKBReader

public WKBReader()

WKBReader

public WKBReader(GeometryFactory geometryFactory)

Method Detail

createClosedRing

public static LineString createClosedRing(LineString seq,
                          int size)

ensureValidRing

public static LineString ensureValidRing(LineString seq)

Ensures that a LineString forms a valid ring, returning a new closed sequence of the correct length if required. If the input sequence is already a valid ring, it is returned without modification. If the input sequence is too short or is not closed, it is extended with one or more copies of the start point.

Parameters:

seq - the sequence to test

geometryFactory - the CoordinateSequenceFactory to use to create the new sequence

Returns:

the original sequence, if it was a valid ring, or a new sequence which is valid.

extend

public static LineString extend(LineString seq,
                int size)

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

isEqual

public static boolean isEqual(LineString cs1,
              LineString cs2)

Tests whether two LineStrings are equal. To be equal, the sequences must be the same length. They do not need to be of the same dimension, but the ordinate values for the smallest dimension of the two must be equal. Two NaN ordinates values are considered to be equal.

Parameters:

cs1 - a LineString

cs2 - a LineString

Returns:

true if the sequences are equal in the common dimensions

isRing

public static boolean isRing(LineString seq)

Tests whether a LineString forms a valid LinearRing, by checking the sequence length and closure (whether the first and last points are identical in 2D). Self-intersection is not checked.

Parameters:

seq - the sequence to test

Returns:

true if the sequence is a ring

See Also:

LinearRing

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