Package ch.so.agi.gretl.internal.shapefile.core

Class ShxWriter

java.lang.Object

ch.so.agi.gretl.internal.shapefile.core.ShxWriter

All Implemented Interfaces:

AutoCloseable

public final class ShxWriter
extends Object
implements AutoCloseable

Low-level writer for the .shx index file.

The index shares the same 100-byte header layout as the .shp file. Each index entry is 8 bytes: the offset and content length, both big-endian and measured in 16-bit words. The offset points at the start of the corresponding .shp record, including its 8-byte record header.

The FileChannel is owned by ShapefileDatasetWriter; close() therefore does not close the channel.

Constructor Summary

Constructors

Constructor	Description
ShxWriter(FileChannel channel)

Method Summary

Modifier and Type	Method	Description
void	close()
void	writeHeader(ShapefileHeader header)	Writes (or patches) the 100-byte index header at the start of the file.
void	writeIndexEntry(long shpOffsetWords, int contentLengthWords)	Appends a single 8-byte index entry at the current channel position.

Methods inherited from class java.lang.Object

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

Constructor Details

ShxWriter

public ShxWriter(FileChannel channel)

Method Details

writeHeader

public void writeHeader(ShapefileHeader header)
                 throws IOException,
ShapefileMappingException

Writes (or patches) the 100-byte index header at the start of the file.

Throws:

IOException

ShapefileMappingException

writeIndexEntry

public void writeIndexEntry(long shpOffsetWords,
 int contentLengthWords)
                     throws IOException,
ShapefileMappingException

Appends a single 8-byte index entry at the current channel position.

Throws:

IOException

ShapefileMappingException

close

public void close()

Specified by:

close in interface AutoCloseable