Package org.apache.pdfbox.io

Class ScratchFileBuffer

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      private void addPage()
      Adds a new page and positions all pointers to start of new page.
      private void checkClosed()
      Checks if this buffer, or the underlying ScratchFile have been closed, throwing IOException if so.
      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.
      RandomAccessReadView createView​(long startPosition, long streamLength)
      Creates a random access read view starting at the given position with the given length.
      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 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.
      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 Detail

      • 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 Detail

      • ScratchFileBuffer

        ScratchFileBuffer​(ScratchFile pageHandler)
           throws java.io.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:
        java.io.IOException - If getting first page failed.

    • Method Detail

      • checkClosed

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

      • addPage

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

      • length

        public long length()
            throws java.io.IOException
        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.

      • ensureAvailableBytesInPage

        private boolean ensureAvailableBytesInPage​(boolean addNewPageIfNeeded)
                                    throws java.io.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:
        java.io.IOException

      • write

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

      • write

        public void write​(byte[] b)
           throws java.io.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:
        java.io.IOException - If there is an error while writing the data.

      • write

        public void write​(byte[] b,
                  int off,
                  int len)
           throws java.io.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:
        java.io.IOException - If there is an error while writing the data.

      • clear

        public final void clear()
                 throws java.io.IOException
        Clears all data of the buffer.
        Specified by:
        clear in interface RandomAccessWrite
        Throws:
        java.io.IOException - If there is an error while clearing the data.

      • getPosition

        public long getPosition()
                 throws java.io.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:
        java.io.IOException - If there was an error while getting the current position

      • seek

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

      • isClosed

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

      • isEOF

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

      • read

        public int read()
         throws java.io.IOException
        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
        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.

      • 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

      • close

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

      • 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