Module org.sejda.sambox

Package org.sejda.sambox.input

Class XrefParser

java.lang.Object

org.sejda.sambox.input.XrefParser

class XrefParser
extends Object

Component responsible for finding and parsing the xref chain (either tables and streams). In case of errors while parsing the xref chain (Ex. invalid offset, bad dictionaries etc) it has a fallback mechanism performing a document full scan searching for xrefs. When parsing the document, xref info are passed to the COSParser which will use them to retrieve COS objects on demand.

See Also:

• XrefFullScanner

Field Summary

Fields

Modifier and Type	Field	Description
private HashSet<Long>	catalogSeenOffsets
private static final int	DEFAULT_TRAIL_BYTECOUNT	How many trailing bytes to read for EOF marker.
private static final org.slf4j.Logger	LOG
private COSParser	parser
private static final String	STARTXREF
private FileTrailer	trailer
private AbstractXrefStreamParser	xrefStreamParser
private AbstractXrefTableParser	xrefTableParser

Constructor Summary

Constructors

Constructor	Description
XrefParser(COSParser parser)

Method Summary

Modifier and Type	Method	Description
private boolean	doParseXref(long xrefOffset)
private long	findXrefOffset()	Looks for the startxref keyword within the latest DEFAULT_TRAIL_BYTECOUNT bytes of the source.
private boolean	isValidXrefOffset(long xrefOffset)
private boolean	isValidXrefStreamOffset(long xrefStreamOffset)
void	parse()	parse the xref using the given parser.
private boolean	parseXref(long xrefOffset)
FileTrailer	trailer()

Methods inherited from class java.lang.Object

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

Field Details

LOG

private static final org.slf4j.Logger LOG

DEFAULT_TRAIL_BYTECOUNT

private static final int DEFAULT_TRAIL_BYTECOUNT

How many trailing bytes to read for EOF marker.

See Also:

• Constant Field Values

STARTXREF

private static final String STARTXREF

See Also:

• Constant Field Values

trailer

private FileTrailer trailer

xrefStreamParser

private AbstractXrefStreamParser xrefStreamParser

xrefTableParser

private AbstractXrefTableParser xrefTableParser

parser

private COSParser parser

catalogSeenOffsets

private HashSet<Long> catalogSeenOffsets

Constructor Details

XrefParser

public XrefParser(COSParser parser)

Method Details

parse

public void parse()
           throws IOException

parse the xref using the given parser.

Throws:

IOException

findXrefOffset

private long findXrefOffset()
                     throws IOException

Looks for the startxref keyword within the latest DEFAULT_TRAIL_BYTECOUNT bytes of the source. If found it returns the Long read after the keyword, if not it returns -1.

Returns:

the xref offset or -1 if the startxref keyword is not found

Throws:

IOException - If something went wrong.

parseXref

private boolean parseXref(long xrefOffset)

doParseXref

private boolean doParseXref(long xrefOffset)
                     throws IOException

Throws:

IOException

isValidXrefOffset

private boolean isValidXrefOffset(long xrefOffset)
                           throws IOException

Parameters:

xrefOffset -

Returns:

true if the given offset points to an xref table or and xref stream

Throws:

IOException

isValidXrefStreamOffset

private boolean isValidXrefStreamOffset(long xrefStreamOffset)
                                 throws IOException

Parameters:

xrefStreamOffset -

Returns:

true if the given offset points to a valid xref stream

Throws:

IOException

trailer

public FileTrailer trailer()