org.locationtech.jts.io

Class WKTReader

java.lang.Object

org.locationtech.jts.io.WKTReader

public class WKTReader
extends java.lang.Object

Converts a geometry in Well-Known Text format to a Geometry.

WKTReader supports extracting Geometry objects from either Readers or Strings. This allows it to function as a parser to read Geometry objects from text blocks embedded in other data formats (e.g. XML).

A WKTReader is parameterized by a GeometryFactory, to allow it to create Geometry objects of the appropriate implementation. In particular, the GeometryFactory determines the PrecisionModel and SRID that is used.

The WKTReader converts all input numbers to the precise internal representation.

Notes:

• Keywords are case-insensitive.
• The reader supports non-standard "LINEARRING" tags.
• The reader uses Double.parseDouble to perform the conversion of ASCII numbers to floating point. This means it supports the Java syntax for floating point literals (including scientific notation).

Syntax

The following syntax specification describes the version of Well-Known Text supported by JTS. (The specification uses a syntax language similar to that used in the C and Java language specifications.)

As of version 1.15, JTS can read (but not write) WKT Strings including Z, M or ZM in the name of the geometry type (ex. POINT Z, LINESTRINGZM). Note that it only makes the reader more flexible, but JTS could already read 3D coordinates from WKT String and still can't read 4D coordinates.

 WKTGeometry: one of

       WKTPoint  WKTLineString  WKTLinearRing  WKTPolygon
       WKTMultiPoint  WKTMultiLineString  WKTMultiPolygon
       WKTGeometryCollection

 WKTPoint: POINT[Dimension] ( Coordinate )

 WKTLineString: LINESTRING[Dimension] CoordinateSequence

 WKTLinearRing: LINEARRING[Dimension] CoordinateSequence

 WKTPolygon: POLYGON[Dimension] CoordinateSequenceList

 WKTMultiPoint: MULTIPOINT[Dimension] CoordinateSingletonList

 WKTMultiLineString: MULTILINESTRING[Dimension] CoordinateSequenceList

 WKTMultiPolygon:
         MULTIPOLYGON[Dimension] ( CoordinateSequenceList { , CoordinateSequenceList } )

 WKTGeometryCollection: 
         GEOMETRYCOLLECTION[Dimension]  ( WKTGeometry { , WKTGeometry } )

 CoordinateSingletonList:
         ( CoordinateSingleton { , CoordinateSingleton } )
         | EMPTY
         
 CoordinateSingleton:
         ( Coordinate )
         | EMPTY

 CoordinateSequenceList:
         ( CoordinateSequence { , CoordinateSequence } )
         | EMPTY

 CoordinateSequence:
         ( Coordinate { , Coordinate } )
         | EMPTY

 Coordinate:
         Number Number Numberopt

 Number: A Java-style floating-point number (including NaN, with arbitrary case)

 Dimension:
         Z| Z|M| M|ZM| ZM

 

Version:

1.7

See Also:

WKTWriter

Field Summary

Fields

Modifier and Type	Field and Description
private static boolean	ALLOW_OLD_JTS_MULTIPOINT_SYNTAX
private static java.lang.String	COMMA
private static java.lang.String	EMPTY
private GeometryFactory	geometryFactory
private static java.lang.String	L_PAREN
private boolean	m
private static java.lang.String	NAN_SYMBOL
private PrecisionModel	precisionModel
private static java.lang.String	R_PAREN
private java.io.StreamTokenizer	tokenizer
private boolean	z

Constructor Summary

Constructors

Constructor and Description
WKTReader() Creates a reader that creates objects using the default GeometryFactory.
WKTReader(GeometryFactory geometryFactory) Creates a reader that creates objects using the given GeometryFactory.

Method Summary

Modifier and Type	Method and Description
private Coordinate[]	getCoordinates() Returns the next array of Coordinates in the stream.
private Coordinate[]	getCoordinatesNoLeftParen()
private java.lang.String	getNextCloser() Returns the next R_PAREN in the stream.
private java.lang.String	getNextCloserOrComma() Returns the next R_PAREN or COMMA in the stream.
private java.lang.String	getNextEmptyOrOpener() Returns the next EMPTY or L_PAREN in the stream as uppercase text.
private double	getNextNumber() Parses the next number in the stream.
private java.lang.String	getNextWord() Returns the next word in the stream.
private Coordinate	getPreciseCoordinate()
private boolean	isNumberNext()
private java.lang.String	lookaheadWord() Returns the next word in the stream.
private void	parseErrorExpected(java.lang.String expected) Throws a formatted ParseException reporting that the current token was unexpected.
private void	parseErrorWithLine(java.lang.String msg)
Geometry	read(java.io.Reader reader) Reads a Well-Known Text representation of a Geometry from a Reader.
Geometry	read(java.lang.String wellKnownText) Reads a Well-Known Text representation of a Geometry from a String.
private GeometryCollection	readGeometryCollectionText() Creates a GeometryCollection using the next token in the stream.
private Geometry	readGeometryTaggedText() Creates a Geometry using the next token in the stream.
private LinearRing	readLinearRingText() Creates a LinearRing using the next token in the stream.
private LineString	readLineStringText() Creates a LineString using the next token in the stream.
private MultiLineString	readMultiLineStringText() Creates a MultiLineString using the next token in the stream.
private MultiPoint	readMultiPointText() Creates a MultiPoint using the next tokens in the stream.
private MultiPolygon	readMultiPolygonText() Creates a MultiPolygon using the next token in the stream.
private Point	readPointText() Creates a Point using the next token in the stream.
private Polygon	readPolygonText() Creates a Polygon using the next token in the stream.
private java.lang.String	tokenString() Gets a description of the current token
private Point[]	toPoints(Coordinate[] coordinates) Creates an array of Points having the given Coordinate s.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

private static final java.lang.String EMPTY

See Also:

Constant Field Values

COMMA

private static final java.lang.String COMMA

See Also:

Constant Field Values

L_PAREN

private static final java.lang.String L_PAREN

See Also:

Constant Field Values

R_PAREN

private static final java.lang.String R_PAREN

See Also:

Constant Field Values

NAN_SYMBOL

private static final java.lang.String NAN_SYMBOL

See Also:

Constant Field Values

geometryFactory

private GeometryFactory geometryFactory

precisionModel

private PrecisionModel precisionModel

tokenizer

private java.io.StreamTokenizer tokenizer

z

private boolean z

m

private boolean m

ALLOW_OLD_JTS_MULTIPOINT_SYNTAX

private static final boolean ALLOW_OLD_JTS_MULTIPOINT_SYNTAX

See Also:

Constant Field Values

Constructor Detail

WKTReader

public WKTReader()

Creates a reader that creates objects using the default GeometryFactory.

WKTReader

public WKTReader(GeometryFactory geometryFactory)

Creates a reader that creates objects using the given GeometryFactory.

Parameters:

geometryFactory - the factory used to create Geometrys.

Method Detail

read

public Geometry read(java.lang.String wellKnownText)
              throws ParseException

Reads a Well-Known Text representation of a Geometry from a String.

Parameters:

wellKnownText - one or more <Geometry Tagged Text> strings (see the OpenGIS Simple Features Specification) separated by whitespace

Returns:

a Geometry specified by wellKnownText

Throws:

ParseException - if a parsing problem occurs

read

public Geometry read(java.io.Reader reader)
              throws ParseException

Reads a Well-Known Text representation of a Geometry from a Reader.

Parameters:

reader - a Reader which will return a <Geometry Tagged Text> string (see the OpenGIS Simple Features Specification)

Returns:

a Geometry read from reader

Throws:

ParseException - if a parsing problem occurs

getCoordinates

private Coordinate[] getCoordinates()
                             throws java.io.IOException,
                                    ParseException

Returns the next array of Coordinates in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next element returned by the stream should be L_PAREN (the beginning of "(x1 y1, x2 y2, ..., xn yn)") or EMPTY.

Returns:

the next array of Coordinates in the stream, or an empty array if EMPTY is the next element returned by the stream.

Throws:

java.io.IOException - if an I/O error occurs

ParseException - if an unexpected token was encountered

getCoordinatesNoLeftParen

private Coordinate[] getCoordinatesNoLeftParen()
                                        throws java.io.IOException,
                                               ParseException

Throws:

java.io.IOException

ParseException

getPreciseCoordinate

private Coordinate getPreciseCoordinate()
                                 throws java.io.IOException,
                                        ParseException

Throws:

java.io.IOException

ParseException

isNumberNext

private boolean isNumberNext()
                      throws java.io.IOException

Throws:

java.io.IOException

getNextNumber

private double getNextNumber()
                      throws java.io.IOException,
                             ParseException

Parses the next number in the stream. Numbers with exponents are handled. NaN values are handled correctly, and the case of the "NaN" symbol is not significant.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be a number.

Returns:

the next number in the stream

Throws:

ParseException - if the next token is not a valid number

java.io.IOException - if an I/O error occurs

getNextEmptyOrOpener

private java.lang.String getNextEmptyOrOpener()
                                       throws java.io.IOException,
                                              ParseException

Returns the next EMPTY or L_PAREN in the stream as uppercase text.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be EMPTY or L_PAREN.

Returns:

the next EMPTY or L_PAREN in the stream as uppercase text.

Throws:

ParseException - if the next token is not EMPTY or L_PAREN

java.io.IOException - if an I/O error occurs

getNextCloserOrComma

private java.lang.String getNextCloserOrComma()
                                       throws java.io.IOException,
                                              ParseException

Returns the next R_PAREN or COMMA in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be R_PAREN or COMMA.

Returns:

the next R_PAREN or COMMA in the stream

Throws:

ParseException - if the next token is not R_PAREN or COMMA

java.io.IOException - if an I/O error occurs

getNextCloser

private java.lang.String getNextCloser()
                                throws java.io.IOException,
                                       ParseException

Returns the next R_PAREN in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be R_PAREN.

Returns:

the next R_PAREN in the stream

Throws:

ParseException - if the next token is not R_PAREN

java.io.IOException - if an I/O error occurs

getNextWord

private java.lang.String getNextWord()
                              throws java.io.IOException,
                                     ParseException

Returns the next word in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be a word.

Returns:

the next word in the stream as uppercase text

Throws:

ParseException - if the next token is not a word

java.io.IOException - if an I/O error occurs

lookaheadWord

private java.lang.String lookaheadWord()
                                throws java.io.IOException,
                                       ParseException

Returns the next word in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next token must be a word.

Returns:

the next word in the stream as uppercase text

Throws:

ParseException - if the next token is not a word

java.io.IOException - if an I/O error occurs

parseErrorExpected

private void parseErrorExpected(java.lang.String expected)
                         throws ParseException

Throws a formatted ParseException reporting that the current token was unexpected.

Parameters:

expected - a description of what was expected

Throws:

ParseException

AssertionFailedException - if an invalid token is encountered

parseErrorWithLine

private void parseErrorWithLine(java.lang.String msg)
                         throws ParseException

Throws:

ParseException

tokenString

private java.lang.String tokenString()

Gets a description of the current token

Returns:

a description of the current token

readGeometryTaggedText

private Geometry readGeometryTaggedText()
                                 throws java.io.IOException,
                                        ParseException

Creates a Geometry using the next token in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <Geometry Tagged Text>.

Returns:

a Geometry specified by the next token in the stream

Throws:

ParseException - if the coordinates used to create a Polygon shell and holes do not form closed linestrings, or if an unexpected token was encountered

java.io.IOException - if an I/O error occurs

readPointText

private Point readPointText()
                     throws java.io.IOException,
                            ParseException

Creates a Point using the next token in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <Point Text>.

Returns:

a Point specified by the next token in the stream

Throws:

java.io.IOException - if an I/O error occurs

ParseException - if an unexpected token was encountered

readLineStringText

private LineString readLineStringText()
                               throws java.io.IOException,
                                      ParseException

Creates a LineString using the next token in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <LineString Text>.

Returns:

a LineString specified by the next token in the stream

Throws:

java.io.IOException - if an I/O error occurs

ParseException - if an unexpected token was encountered

readLinearRingText

private LinearRing readLinearRingText()
                               throws java.io.IOException,
                                      ParseException

Creates a LinearRing using the next token in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <LineString Text>.

Returns:

a LinearRing specified by the next token in the stream

Throws:

java.io.IOException - if an I/O error occurs

ParseException - if the coordinates used to create the LinearRing do not form a closed linestring, or if an unexpected token was encountered

readMultiPointText

private MultiPoint readMultiPointText()
                               throws java.io.IOException,
                                      ParseException

Creates a MultiPoint using the next tokens in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <MultiPoint Text>.

Returns:

a MultiPoint specified by the next token in the stream

Throws:

java.io.IOException - if an I/O error occurs

ParseException - if an unexpected token was encountered

toPoints

private Point[] toPoints(Coordinate[] coordinates)

Creates an array of Points having the given Coordinate s.

Parameters:

coordinates - the Coordinates with which to create the Points

Returns:

Points created using this WKTReader s GeometryFactory

readPolygonText

private Polygon readPolygonText()
                         throws java.io.IOException,
                                ParseException

Creates a Polygon using the next token in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <Polygon Text>.

Returns:

a Polygon specified by the next token in the stream

Throws:

ParseException - if the coordinates used to create the Polygon shell and holes do not form closed linestrings, or if an unexpected token was encountered.

java.io.IOException - if an I/O error occurs

readMultiLineStringText

private MultiLineString readMultiLineStringText()
                                         throws java.io.IOException,
                                                ParseException

Creates a MultiLineString using the next token in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <MultiLineString Text>.

Returns:

a MultiLineString specified by the next token in the stream

Throws:

java.io.IOException - if an I/O error occurs

ParseException - if an unexpected token was encountered

readMultiPolygonText

private MultiPolygon readMultiPolygonText()
                                   throws java.io.IOException,
                                          ParseException

Creates a MultiPolygon using the next token in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <MultiPolygon Text>.

Returns:

a MultiPolygon specified by the next token in the stream, or if if the coordinates used to create the Polygon shells and holes do not form closed linestrings.

Throws:

java.io.IOException - if an I/O error occurs

ParseException - if an unexpected token was encountered

readGeometryCollectionText

private GeometryCollection readGeometryCollectionText()
                                               throws java.io.IOException,
                                                      ParseException

Creates a GeometryCollection using the next token in the stream.

Parameters:

tokenizer - tokenizer over a stream of text in Well-known Text format. The next tokens must form a <GeometryCollection Text>.

Returns:

a GeometryCollection specified by the next token in the stream

Throws:

ParseException - if the coordinates used to create a Polygon shell and holes do not form closed linestrings, or if an unexpected token was encountered

java.io.IOException - if an I/O error occurs