com.bc.ceres.binio

Interface IOHandler

All Known Implementing Classes:

ByteArrayIOHandler, FileChannelIOHandler, FilterIOHandler, ImageIOHandler, MappedFileChannelIOHandler, RandomAccessFileIOHandler

public interface IOHandler

Provides the mechanism to read and write byte data at a specified position within a random access data file, stream or memory buffer.

Method Summary

Modifier and Type	Method and Description
long	getMaxPosition() Returns the current size of the backing file, array or stream.
void	read(DataContext context, byte[] data, long position) Reads a sequence of up to data.length bytes into the given array starting from the the given position.
void	write(DataContext context, byte[] data, long position) Writes a sequence of up to data.length bytes to the file, starting at the given position.

Method Detail

read

void read(DataContext context,
          byte[] data,
          long position)
   throws IOException

Reads a sequence of up to data.length bytes into the given array starting from the the given position. If the position is greater than the file's current size then no bytes are read.

A read operation might not fill the array, and in fact it might not read any bytes at all. Whether or not it does so, depends upon the state of the file, e.g. only bytes that remain in the file starting from the given position will be read.

Parameters:

context - The I/O context.

data - The data array into which bytes are to be transferred.

position - The file position at which the transfer is to begin; must be non-negative.

Throws:

IOException - If an I/O error occurs.

write

void write(DataContext context,
           byte[] data,
           long position)
    throws IOException

Writes a sequence of up to data.length bytes to the file, starting at the given position. If the given position is greater than the file's current size then the file will be grown to accommodate the new bytes; the values of any bytes between the previous end-of-file and the newly-written bytes are unspecified.

Parameters:

context - The I/O context.

data - The data array from which bytes are to be transferred.

position - The file position at which the transfer is to begin; must be non-negative.

Throws:

IOException - If an I/O error occurs.

getMaxPosition

long getMaxPosition()
             throws IOException

Returns the current size of the backing file, array or stream.

This value may change, while writing to a growing file or array. If the value is unknown -1 will be returned.

Returns:

Te maximum position.

Throws:

IOException - If an I/O error occurs.