uk.ac.starlink.fits
Class SimpleMappedInput

java.lang.Object
  uk.ac.starlink.fits.SimpleMappedInput

All Implemented Interfaces:

BasicInput

public class SimpleMappedInput
extends Object
implements BasicInput

Random-access BasicInput implementation that maps a given region of a file as a monolithic byte buffer. On close, an attempt is made to unmap the buffer.

Note: DO NOT use an instance of this class from multiple threads - see Unmapper.

Since:

1 Dec 2014

Constructor Summary

SimpleMappedInput(FileChannel chan, long pos, int size, String logName)
Constructor.

Method Summary

void	close() Releases resources belonging to this object.
long	getOffset() Returns the curent position in this stream (optional operation).
boolean	isRandom() Indicates whether this object supports random access.
byte	readByte() Reads a byte from the stream.
double	readDouble() Reads an 8-byte floating point value from the stream.
float	readFloat() Reads a 4-byte floating point value from the stream.
int	readInt() Reads a 4-byte integer from the stream.
long	readLong() Reads an 8-byte integer from the stream.
short	readShort() Reads a 2-byte integer from the stream.
void	seek(long pos) Moves the current position of this stream to a given byte offset (optional operation).
void	skip(long nbyte) Skips a given number of bytes forwards through the stream.

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleMappedInput

public SimpleMappedInput(FileChannel chan,
                         long pos,
                         int size,
                         String logName)
                  throws IOException

Constructor.

Parameters:

chan - file channel, preferably read-only

pos - offset into file of stream start

size - number of bytes in stream

logName - name for mapped region used in logging messages

Throws:

IOException

Method Detail

isRandom

public boolean isRandom()

Description copied from interface: BasicInput

Indicates whether this object supports random access. The seek and getOffset methods may only be called if this method returns true.

Specified by:

isRandom in interface BasicInput

Returns:

true iff random access is supported

seek

public void seek(long pos)
          throws EOFException

Description copied from interface: BasicInput

Moves the current position of this stream to a given byte offset (optional operation).

Specified by:

seek in interface BasicInput

Throws:

EOFException

getOffset

public long getOffset()

Description copied from interface: BasicInput

Returns the curent position in this stream (optional operation).

Specified by:

getOffset in interface BasicInput

skip

public void skip(long nbyte)
          throws IOException

Description copied from interface: BasicInput

Skips a given number of bytes forwards through the stream. An exception is thrown if there are not enough bytes left.

Specified by:

skip in interface BasicInput

Parameters:

nbyte - number of bytes to skip

Throws:

IOException

readByte

public byte readByte()
              throws EOFException

Description copied from interface: BasicInput

Reads a byte from the stream. The current position is advanced.

Specified by:

readByte in interface BasicInput

Returns:

byte value

Throws:

EOFException

readShort

public short readShort()
                throws EOFException

Description copied from interface: BasicInput

Reads a 2-byte integer from the stream. The current position is advanced.

Specified by:

readShort in interface BasicInput

Returns:

short value

Throws:

EOFException

readInt

public int readInt()
            throws EOFException

Description copied from interface: BasicInput

Reads a 4-byte integer from the stream. The current position is advanced.

Specified by:

readInt in interface BasicInput

Returns:

int value

Throws:

EOFException

readLong

public long readLong()
              throws EOFException

Description copied from interface: BasicInput

Reads an 8-byte integer from the stream. The current position is advanced.

Specified by:

readLong in interface BasicInput

Returns:

long value

Throws:

EOFException

readFloat

public float readFloat()
                throws EOFException

Description copied from interface: BasicInput

Reads a 4-byte floating point value from the stream. The current position is advanced.

Specified by:

readFloat in interface BasicInput

Returns:

float value

Throws:

EOFException

readDouble

public double readDouble()
                  throws EOFException

Description copied from interface: BasicInput

Reads an 8-byte floating point value from the stream. The current position is advanced.

Specified by:

readDouble in interface BasicInput

Returns:

double value

Throws:

EOFException

close

public void close()

Description copied from interface: BasicInput

Releases resources belonging to this object. Attempts to use it after a call to this method result in undefined behaviour.

Specified by:

close in interface BasicInput