public class WKBWriter
extends java.lang.Object
Geometry
into Well-Known Binary format.
Supports use of an OutStream
, which allows easy use
with arbitrary byte stream sinks.
The WKB format is specified in the OGC Simple Features for SQL specification. This implementation also supports the Extended WKB standard. Extended WKB allows writing 3-dimensional coordinates and including the geometry SRID value. The presence of 3D coordinates is signified by setting the high bit of the wkbType word. The presence of an SRID is signified by setting the third bit of the wkbType word. EWKB format is upward compatible with the original SFS WKB format.
Empty Points cannot be represented in WKB; an
IllegalArgumentException
will be thrown if one is
written.
The WKB specification does not support representing LinearRing
s;
they will be written as LineString
s.
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.
The specification uses a syntax language similar to that used in the C language. Bitfields are specified from hi-order to lo-order bits.
byte = 1 byte uint32 = 32 bit unsigned integer (4 bytes) double = double precision number (8 bytes) abstract Point { } Point2D extends Point { double x; double y; } Point3D extends Point { double x; double y; double z; } LinearRing { uint32 numPoints; Point points[numPoints]; } enum wkbGeometryType { wkbPoint = 1, wkbLineString = 2, wkbPolygon = 3, wkbMultiPoint = 4, wkbMultiLineString = 5, wkbMultiPolygon = 6, wkbGeometryCollection = 7 } enum byteOrder { wkbXDR = 0, // Big Endian wkbNDR = 1 // Little Endian } WKBType { uint32 wkbGeometryType : 8; // values from enum wkbGeometryType } EWKBType { uint32 is3D : 1; // 0 = 2D, 1 = 3D uint32 noData1 : 1; uint32 hasSRID : 1; // 0, no, 1 = yes uint32 noData2 : 21; uint32 wkbGeometryType : 8; // values from enum wkbGeometryType } abstract WKBGeometry { byte byteOrder; // values from enum byteOrder EWKBType wkbType [ uint32 srid; ] // only if hasSRID = yes } WKBPoint extends WKBGeometry { Point point; } WKBLineString extends WKBGeometry { uint32 numCoords; Point points[numCoords]; } WKBPolygon extends WKBGeometry { uint32 numRings; LinearRing rings[numRings]; } WKBMultiPoint extends WKBGeometry { uint32 numElems; WKBPoint elems[numElems]; } WKBMultiLineString extends WKBGeometry { uint32 numElems; WKBLineString elems[numElems]; } wkbMultiPolygon extends WKBGeometry { uint32 numElems; WKBPolygon elems[numElems]; } WKBGeometryCollection extends WKBGeometry { uint32 numElems; WKBGeometry elems[numElems]; }
WKBReader
Constructor | Description |
---|---|
WKBWriter() |
Creates a writer that writes
Geometry s with
output dimension = 2 and BIG_ENDIAN byte order |
WKBWriter(int outputDimension) |
Creates a writer that writes
Geometry s with
the given dimension (2 or 3) for output coordinates
and ByteOrderValues.BIG_ENDIAN byte order. |
WKBWriter(int outputDimension,
boolean includeSRID) |
Creates a writer that writes
Geometry s with
the given dimension (2 or 3) for output coordinates
and ByteOrderValues.BIG_ENDIAN byte order. |
WKBWriter(int outputDimension,
int byteOrder) |
Creates a writer that writes
Geometry s with
the given dimension (2 or 3) for output coordinates
and byte order
If the input geometry has a small coordinate dimension,
coordinates will be padded with Coordinate.NULL_ORDINATE . |
WKBWriter(int outputDimension,
int byteOrder,
boolean includeSRID) |
Creates a writer that writes
Geometry s with
the given dimension (2 or 3) for output coordinates
and byte order. |
Modifier and Type | Method | Description |
---|---|---|
static java.lang.String |
bytesToHex(byte[] bytes) |
Deprecated.
|
static java.lang.String |
toHex(byte[] bytes) |
Converts a byte array to a hexadecimal string.
|
byte[] |
write(Geometry geom) |
Writes a
Geometry into a byte array. |
void |
write(Geometry geom,
OutStream os) |
public WKBWriter()
Geometry
s with
output dimension = 2 and BIG_ENDIAN byte orderpublic WKBWriter(int outputDimension)
Geometry
s with
the given dimension (2 or 3) for output coordinates
and ByteOrderValues.BIG_ENDIAN
byte order.
If the input geometry has a small coordinate dimension,
coordinates will be padded with Coordinate.NULL_ORDINATE
.outputDimension
- the coordinate dimension to output (2 or 3)public WKBWriter(int outputDimension, boolean includeSRID)
Geometry
s with
the given dimension (2 or 3) for output coordinates
and ByteOrderValues.BIG_ENDIAN
byte order. This constructor also
takes a flag to control whether srid information will be
written.
If the input geometry has a smaller coordinate dimension,
coordinates will be padded with Coordinate.NULL_ORDINATE
.outputDimension
- the coordinate dimension to output (2 or 3)includeSRID
- indicates whether SRID should be writtenpublic WKBWriter(int outputDimension, int byteOrder)
Geometry
s with
the given dimension (2 or 3) for output coordinates
and byte order
If the input geometry has a small coordinate dimension,
coordinates will be padded with Coordinate.NULL_ORDINATE
.outputDimension
- the coordinate dimension to output (2 or 3)byteOrder
- the byte ordering to usepublic WKBWriter(int outputDimension, int byteOrder, boolean includeSRID)
Geometry
s with
the given dimension (2 or 3) for output coordinates
and byte order. This constructor also takes a flag to
control whether srid information will be written.
If the input geometry has a small coordinate dimension,
coordinates will be padded with Coordinate.NULL_ORDINATE
.outputDimension
- the coordinate dimension to output (2 or 3)byteOrder
- the byte ordering to useincludeSRID
- indicates whether SRID should be writtenpublic static java.lang.String bytesToHex(byte[] bytes)
bytes
- public static java.lang.String toHex(byte[] bytes)
bytes
- a byte arraypublic byte[] write(Geometry geom)
Geometry
into a byte array.geom
- the geometry to writeCopyright © 2018. All rights reserved.