Class GroupedRandomAccessSource

  • All Implemented Interfaces:
    RandomAccessSource
    Direct Known Subclasses:
    PagedChannelRandomAccessSource

    class GroupedRandomAccessSource
    extends java.lang.Object
    implements RandomAccessSource
    A RandomAccessSource that is based on a set of underlying sources, treating the sources as if they were a contiguous block of data.
    Since:
    5.3.5
    • Field Detail

      • size

        private final long size
        Cached size of the underlying channel
    • Constructor Detail

      • GroupedRandomAccessSource

        public GroupedRandomAccessSource​(RandomAccessSource[] sources)
                                  throws java.io.IOException
        Constructs a new GroupedRandomAccessSource based on the specified set of sources
        Parameters:
        sources - the sources used to build this group
        Throws:
        java.io.IOException
    • Method Detail

      • getStartingSourceIndex

        protected int getStartingSourceIndex​(long offset)
        For a given offset, return the index of the source that contains the specified offset. This is an optimization feature to help optimize the access of the correct source without having to iterate through every single source each time. It is safe to always return 0, in which case the full set of sources will be searched. Subclasses should override this method if they are able to compute the source index more efficiently (for example FileChannelRandomAccessSource takes advantage of fixed size page buffers to compute the index)
        Parameters:
        offset - the offset
        Returns:
        the index of the input source that contains the specified offset, or 0 if unknown
      • getSourceEntryForOffset

        private GroupedRandomAccessSource.SourceEntry getSourceEntryForOffset​(long offset)
                                                                       throws java.io.IOException
        Returns the SourceEntry that contains the byte at the specified offset sourceReleased is called as a notification callback so subclasses can take care of cleanup when the source is no longer the active source
        Parameters:
        offset - the offset of the byte to look for
        Returns:
        the SourceEntry that contains the byte at the specified offset
        Throws:
        java.io.IOException - if there is a problem with IO (usually the result of the sourceReleased() call)
      • sourceReleased

        protected void sourceReleased​(RandomAccessSource source)
                               throws java.io.IOException
        Called when a given source is no longer the active source. This gives subclasses the abilty to release resources, if appropriate.
        Parameters:
        source - the source that is no longer the active source
        Throws:
        java.io.IOException - if there are any problems
      • sourceInUse

        protected void sourceInUse​(RandomAccessSource source)
                            throws java.io.IOException
        Called when a given source is about to become the active source. This gives subclasses the abilty to retrieve resources, if appropriate.
        Parameters:
        source - the source that is about to become the active source
        Throws:
        java.io.IOException - if there are any problems
      • get

        public int get​(long position)
                throws java.io.IOException
        Gets a byte at the specified position The source that contains the byte at position is retrieved, the correct offset into that source computed, then the value from that offset in the underlying source is returned.
        Specified by:
        get in interface RandomAccessSource
        Returns:
        the byte, or -1 if EOF is reached
        Throws:
        java.io.IOException
      • get

        public int get​(long position,
                       byte[] bytes,
                       int off,
                       int len)
                throws java.io.IOException
        Gets an array at the specified position. If the number of bytes requested cannot be read, the bytes that can be read will be placed in bytes and the number actually read will be returned.
        Specified by:
        get in interface RandomAccessSource
        Parameters:
        position - the position in the RandomAccessSource to read from
        bytes - output buffer
        off - offset into the output buffer where results will be placed
        len - the number of bytes to read
        Returns:
        the number of bytes actually read, or -1 if the file is at EOF
        Throws:
        java.io.IOException
      • length

        public long length()
        Specified by:
        length in interface RandomAccessSource
        Returns:
        the length of this source
      • close

        public void close()
                   throws java.io.IOException
        Closes this source. The underlying data structure or source (if any) will also be closed Closes all of the underlying sources
        Specified by:
        close in interface RandomAccessSource
        Throws:
        java.io.IOException