Package org.apache.pdfbox.io

Class RandomAccessReadBufferedFile

java.lang.Object

org.apache.pdfbox.io.RandomAccessReadBufferedFile

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, RandomAccessRead

public class RandomAccessReadBufferedFile
extends java.lang.Object
implements RandomAccessRead

Provides random access to portions of a file combined with buffered reading of content. Start of next bytes to read can be set via seek method. File is accessed via FileChannel and is read in ByteBuffer chunks which are cached.

Field Summary

Fields

Modifier and Type	Field	Description
private java.nio.ByteBuffer	curPage
private long	curPageOffset
private java.nio.channels.FileChannel	fileChannel
private long	fileLength
private long	fileOffset
private boolean	isClosed
private java.nio.ByteBuffer	lastRemovedCachePage
private static int	MAX_CACHED_PAGES
private int	offsetWithinPage
private static long	PAGE_OFFSET_MASK
private static int	PAGE_SIZE
private static int	PAGE_SIZE_SHIFT
private java.util.Map<java.lang.Long,java.nio.ByteBuffer>	pageCache	Create a LRU page cache.
private java.nio.file.Path	path
private java.util.concurrent.ConcurrentMap<java.lang.Long,RandomAccessReadBufferedFile>	rafCopies

Constructor Summary

Constructors

Constructor	Description
RandomAccessReadBufferedFile(java.io.File file)	Create a random access buffered file instance for the given file.
RandomAccessReadBufferedFile(java.lang.String filename)	Create a random access buffered file instance for the file with the given name.
RandomAccessReadBufferedFile(java.nio.file.Path path)	Create a random access buffered file instance using the given path.

Method Summary

Modifier and Type	Method	Description
private void	checkClosed()	Ensure that the RandomAccessBuffer is not closed
void	close()
RandomAccessReadView	createView(long startPosition, long streamLength)	Creates a random access read view starting at the given position with the given length.
long	getPosition()	Returns offset of next byte to be returned by a read method.
boolean	isClosed()	Returns true if this source has been closed.
boolean	isEOF()	A simple test to see if we are at the end of the data.
long	length()	The total number of bytes that are available.
int	read()	Read a single byte of data.
int	read(byte[] b, int off, int len)	Read a buffer of data.
private java.nio.ByteBuffer	readPage()	Reads a page with data from current file position.
void	seek(long position)	Seeks to new position.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.pdfbox.io.RandomAccessRead

available, peek, read, rewind, skip

Field Detail

PAGE_SIZE_SHIFT

private static final int PAGE_SIZE_SHIFT

See Also:

Constant Field Values

PAGE_SIZE

private static final int PAGE_SIZE

See Also:

Constant Field Values

PAGE_OFFSET_MASK

private static final long PAGE_OFFSET_MASK

See Also:

Constant Field Values

MAX_CACHED_PAGES

private static final int MAX_CACHED_PAGES

See Also:

Constant Field Values

rafCopies

private final java.util.concurrent.ConcurrentMap<java.lang.Long,RandomAccessReadBufferedFile> rafCopies

lastRemovedCachePage

private java.nio.ByteBuffer lastRemovedCachePage

pageCache

private final java.util.Map<java.lang.Long,java.nio.ByteBuffer> pageCache

Create a LRU page cache.

curPageOffset

private long curPageOffset

curPage

private java.nio.ByteBuffer curPage

offsetWithinPage

private int offsetWithinPage

fileChannel

private final java.nio.channels.FileChannel fileChannel

path

private final java.nio.file.Path path

fileLength

private final long fileLength

fileOffset

private long fileOffset

isClosed

private boolean isClosed

Constructor Detail

RandomAccessReadBufferedFile

public RandomAccessReadBufferedFile(java.lang.String filename)
                             throws java.io.IOException

Create a random access buffered file instance for the file with the given name.

Parameters:

filename - the filename of the file to be read.

Throws:

java.io.IOException - if something went wrong while accessing the given file.

RandomAccessReadBufferedFile

public RandomAccessReadBufferedFile(java.io.File file)
                             throws java.io.IOException

Create a random access buffered file instance for the given file.

Parameters:

file - the file to be read.

Throws:

java.io.IOException - if something went wrong while accessing the given file.

RandomAccessReadBufferedFile

public RandomAccessReadBufferedFile(java.nio.file.Path path)
                             throws java.io.IOException

Create a random access buffered file instance using the given path.

Parameters:

path - path of the file to be read.

Throws:

java.io.IOException - if something went wrong while accessing the given file.

Method Detail

getPosition

public long getPosition()
                 throws java.io.IOException

Description copied from interface: RandomAccessRead

Returns offset of next byte to be returned by a read method.

Specified by:

getPosition in interface RandomAccessRead

Returns:

offset of next byte which will be returned with next RandomAccessRead.read() (if no more bytes are left it returns a value >= length of source)

Throws:

java.io.IOException - If there was an error while getting the current position

seek

public void seek(long position)
          throws java.io.IOException

Seeks to new position. If new position is outside of current page the new page is either taken from cache or read from file and added to cache.

Specified by:

seek in interface RandomAccessRead

Parameters:

position - the position to seek to.

Throws:

java.io.IOException - if something went wrong.

readPage

private java.nio.ByteBuffer readPage()
                              throws java.io.IOException

Reads a page with data from current file position. If we have a previously removed page from cache the buffer of this page is reused. Otherwise a new byte buffer is created.

Throws:

java.io.IOException

read

public int read()
         throws java.io.IOException

Description copied from interface: RandomAccessRead

Read a single byte of data.

Specified by:

read in interface RandomAccessRead

Returns:

The byte of data that is being read.

Throws:

java.io.IOException - If there is an error while reading the data.

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Description copied from interface: RandomAccessRead

Read a buffer of data.

Specified by:

read in interface RandomAccessRead

Parameters:

b - The buffer to write the data to.

off - Offset into the buffer to start writing.

len - The amount of data to attempt to read.

Returns:

The number of bytes that were actually read.

Throws:

java.io.IOException - If there was an error while reading the data.

length

public long length()
            throws java.io.IOException

Description copied from interface: RandomAccessRead

The total number of bytes that are available.

Specified by:

length in interface RandomAccessRead

Returns:

The number of bytes available.

Throws:

java.io.IOException - If there is an IO error while determining the length of the data stream.

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Throws:

java.io.IOException

isClosed

public boolean isClosed()

Description copied from interface: RandomAccessRead

Returns true if this source has been closed.

Specified by:

isClosed in interface RandomAccessRead

Returns:

true if the source has been closed

checkClosed

private void checkClosed()
                  throws java.io.IOException

Ensure that the RandomAccessBuffer is not closed

Throws:

java.io.IOException - If RandomAccessBuffer already closed

isEOF

public boolean isEOF()
              throws java.io.IOException

Description copied from interface: RandomAccessRead

A simple test to see if we are at the end of the data.

Specified by:

isEOF in interface RandomAccessRead

Returns:

true if we are at the end of the data.

Throws:

java.io.IOException - If there is an error reading the next byte.

createView

public RandomAccessReadView createView(long startPosition,
                                       long streamLength)
                                throws java.io.IOException

Description copied from interface: RandomAccessRead

Creates a random access read view starting at the given position with the given length.

Specified by:

createView in interface RandomAccessRead

Parameters:

startPosition - start position within the underlying random access read

streamLength - stream length

Returns:

the random access read view

Throws:

java.io.IOException - if something went wrong when creating the view for the RandomAccessRead