Package org.apache.pdfbox.io

Class ScratchFileBuffer

java.lang.Object
org.apache.pdfbox.io.ScratchFileBuffer
All Implemented Interfaces:
Closeable, AutoCloseable, RandomAccess, RandomAccessRead, RandomAccessWrite
class ScratchFileBuffer extends Object implements RandomAccess
Implementation of RandomAccess as sequence of multiple fixed size pages handled by ScratchFile.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private byte[]
    currentPage
    The current page data.
    private boolean
    currentPageContentChanged
    true if current page was changed by a write method
    private long
    currentPageOffset
    The offset of the current page within this buffer.
    private int
    currentPagePositionInPageIndexes
    Index of current page in pageIndexes (the nth page within this buffer).
    private int
    pageCount
    number of pages held by this buffer
    private ScratchFile
    pageHandler
    The underlying page handler.
    private int[]
    pageIndexes
    contains ordered list of pages with the index the page is known by page handler (ScratchFile)
    private final int
    pageSize
     
    private int
    positionInPage
    The current position (for next read/write) of the buffer as an offset in the current page.
    private long
    size
    The number of bytes of content in this buffer.

  • Constructor Summary

    Constructors
    Constructor
    Description
    ScratchFileBuffer(ScratchFile pageHandler)
    Creates a new buffer using pages handled by provided ScratchFile.

  • Method Summary

    Modifier and Type
    Method
    Description
    private void
    addPage()
    Adds a new page and positions all pointers to start of new page.
    int
    available()
    Returns an estimate of the number of bytes that can be read.
    private void
    checkClosed()
    Checks if this buffer, or the underlying ScratchFile have been closed, throwing IOException if so.
    final void
    clear()
    Clears all data of the buffer.
    void
    close()
    (package private) void
    close(boolean removeBuffer)
    Release all resources and remove this buffer from ScratchFile.
    private boolean
    ensureAvailableBytesInPage(boolean addNewPageIfNeeded)
    Ensures the current page has at least one byte left (positionInPage in < pageSize).
    long
    getPosition()
    Returns offset of next byte to be returned by a read method.
    boolean
    isClosed()
    Returns true if this stream 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
    peek()
    This will peek at the next byte.
    int
    read()
    Read a single byte of data.
    int
    read(byte[] b)
    Read a buffer of data.
    int
    read(byte[] b, int off, int len)
    Read a buffer of data.
    byte[]
    readFully(int length)
    Reads a given number of bytes.
    void
    rewind(int bytes)
    Seek backwards the given number of bytes.
    void
    seek(long seekToPosition)
    Seek to a position in the data.
    void
    write(byte[] b)
    Write a buffer of data to the stream.
    void
    write(byte[] b, int off, int len)
    Write a buffer of data to the stream.
    void
    write(int b)
    Write a byte to the stream.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • pageSize

      private final int pageSize

    • pageHandler

      private ScratchFile pageHandler
      The underlying page handler.

    • size

      private long size
      The number of bytes of content in this buffer.

    • currentPagePositionInPageIndexes

      private int currentPagePositionInPageIndexes
      Index of current page in pageIndexes (the nth page within this buffer).

    • currentPageOffset

      private long currentPageOffset
      The offset of the current page within this buffer.

    • currentPage

      private byte[] currentPage
      The current page data.

    • positionInPage

      private int positionInPage
      The current position (for next read/write) of the buffer as an offset in the current page.

    • currentPageContentChanged

      private boolean currentPageContentChanged
      true if current page was changed by a write method

    • pageIndexes

      private int[] pageIndexes
      contains ordered list of pages with the index the page is known by page handler (ScratchFile)

    • pageCount

      private int pageCount
      number of pages held by this buffer

  • Constructor Details

    • ScratchFileBuffer

      ScratchFileBuffer(ScratchFile pageHandler) throws IOException
      Creates a new buffer using pages handled by provided ScratchFile.
      Parameters:
      pageHandler - The ScratchFile managing the pages to be used by this buffer.
      Throws:
      IOException - If getting first page failed.

  • Method Details

    • checkClosed

      private void checkClosed() throws IOException
      Checks if this buffer, or the underlying ScratchFile have been closed, throwing IOException if so.
      Throws:
      IOException - If either this buffer, or the underlying ScratchFile have been closed.

    • addPage

      private void addPage() throws IOException
      Adds a new page and positions all pointers to start of new page.
      Throws:
      IOException - if requesting a new page fails

    • length

      public long length() throws IOException
      The total number of bytes that are available.
      Specified by:
      length in interface RandomAccessRead
      Returns:
      The number of bytes available.
      Throws:
      IOException - If there is an IO error while determining the length of the data stream.

    • ensureAvailableBytesInPage

      private boolean ensureAvailableBytesInPage(boolean addNewPageIfNeeded) throws IOException
      Ensures the current page has at least one byte left (positionInPage in < pageSize).

      If this is not the case we go to next page (writing current one if changed). If current buffer has no more pages we add a new one.

      Parameters:
      addNewPageIfNeeded - if true it is allowed to add a new page in case we are currently at end of last buffer page
      Returns:
      true if we were successful positioning pointer before end of page; we might return false if it is not allowed to add another page and current pointer points at end of last page
      Throws:
      IOException

    • write

      public void write(int b) throws IOException
      Write a byte to the stream.
      Specified by:
      write in interface RandomAccessWrite
      Parameters:
      b - The byte to write.
      Throws:
      IOException - If there is an IO error while writing.

    • write

      public void write(byte[] b) throws IOException
      Write a buffer of data to the stream.
      Specified by:
      write in interface RandomAccessWrite
      Parameters:
      b - The buffer to get the data from.
      Throws:
      IOException - If there is an error while writing the data.

    • write

      public void write(byte[] b, int off, int len) throws IOException
      Write a buffer of data to the stream.
      Specified by:
      write in interface RandomAccessWrite
      Parameters:
      b - The buffer to get the data from.
      off - An offset into the buffer to get the data from.
      len - The length of data to write.
      Throws:
      IOException - If there is an error while writing the data.

    • clear

      public final void clear() throws IOException
      Clears all data of the buffer.
      Specified by:
      clear in interface RandomAccessWrite
      Throws:
      IOException

    • getPosition

      public long getPosition() throws IOException
      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:
      IOException

    • seek

      public void seek(long seekToPosition) throws IOException
      Seek to a position in the data.
      Specified by:
      seek in interface RandomAccessRead
      Parameters:
      seekToPosition - The position to seek to.
      Throws:
      IOException - If there is an error while seeking.

    • isClosed

      public boolean isClosed()
      Returns true if this stream has been closed.
      Specified by:
      isClosed in interface RandomAccessRead

    • peek

      public int peek() throws IOException
      This will peek at the next byte.
      Specified by:
      peek in interface RandomAccessRead
      Returns:
      The next byte on the stream, leaving it as available to read.
      Throws:
      IOException - If there is an error reading the next byte.

    • rewind

      public void rewind(int bytes) throws IOException
      Seek backwards the given number of bytes.
      Specified by:
      rewind in interface RandomAccessRead
      Parameters:
      bytes - the number of bytes to be seeked backwards
      Throws:
      IOException - If there is an error while seeking

    • readFully

      public byte[] readFully(int length) throws IOException
      Reads a given number of bytes.
      Specified by:
      readFully in interface RandomAccessRead
      Parameters:
      length - the number of bytes to be read
      Returns:
      a byte array containing the bytes just read
      Throws:
      IOException - if an I/O error occurs while reading data

    • isEOF

      public boolean isEOF() throws IOException
      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:
      IOException - If there is an error reading the next byte.

    • available

      public int available() throws IOException
      Returns an estimate of the number of bytes that can be read.
      Specified by:
      available in interface RandomAccessRead
      Returns:
      the number of bytes that can be read
      Throws:
      IOException - if this random access has been closed

    • read

      public int read() throws IOException
      Read a single byte of data.
      Specified by:
      read in interface RandomAccessRead
      Returns:
      The byte of data that is being read.
      Throws:
      IOException - If there is an error while reading the data.

    • read

      public int read(byte[] b) throws IOException
      Read a buffer of data.
      Specified by:
      read in interface RandomAccessRead
      Parameters:
      b - The buffer to write the data to.
      Returns:
      The number of bytes that were actually read.
      Throws:
      IOException - If there was an error while reading the data.

    • read

      public int read(byte[] b, int off, int len) throws IOException
      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:
      IOException - If there was an error while reading the data.

    • close

      public void close() throws IOException
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Throws:
      IOException

    • close

      void close(boolean removeBuffer)
      Release all resources and remove this buffer from ScratchFile.
      Parameters:
      removeBuffer - remove buffer from ScratchFile if set to true