uk.ac.starlink.fits

Class BufferedRandomInput

java.lang.Object

uk.ac.starlink.fits.BufferedRandomInput

All Implemented Interfaces:

BasicInput

public class BufferedRandomInput
extends Object
implements BasicInput

BasicInput implementation based on a RandomAccessFile. Buffering of the underlying file is performed on the assumption that access will be largely sequential.

Since:

8 Nov 2017

Author:

Mark Taylor

Field Summary

Fields

Modifier and Type	Field and Description
static int	DFLT_BUFSIZE

Constructor Summary

Constructors

Constructor and Description
BufferedRandomInput(RandomAccessFile file, long offset0) Constructs a BufferedRandomInput with a default sized buffer.
BufferedRandomInput(RandomAccessFile file, long offset0, int bufsize) Constructs a BufferedRandomInput with a buffer of specified size.

Method Summary

Modifier and Type	Method and Description
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.
void	readBytes(byte[] bbuf) Reads bytes into an array 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 offset) Moves the current position of this stream to a given byte offset (optional operation).
void	skip(long nbytes) 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

Field Detail

DFLT_BUFSIZE

public static final int DFLT_BUFSIZE

Constructor Detail

BufferedRandomInput

public BufferedRandomInput(RandomAccessFile file,
                           long offset0)
                    throws IOException

Constructs a BufferedRandomInput with a default sized buffer.

Parameters:

file - file

offset0 - offset into file of stream start

Throws:

IOException

BufferedRandomInput

public BufferedRandomInput(RandomAccessFile file,
                           long offset0,
                           int bufsize)
                    throws IOException

Constructs a BufferedRandomInput with a buffer of specified size.

Parameters:

file - file

offset0 - offset into file of stream start

bufsize - buffer size

Throws:

IOException

Method Detail

readByte

public byte readByte()
              throws IOException

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:

IOException

readShort

public short readShort()
                throws IOException

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:

IOException

readInt

public int readInt()
            throws IOException

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:

IOException

readLong

public long readLong()
              throws IOException

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:

IOException

readFloat

public float readFloat()
                throws IOException

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:

IOException

readDouble

public double readDouble()
                  throws IOException

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:

IOException

readBytes

public void readBytes(byte[] bbuf)
               throws IOException

Description copied from interface: BasicInput

Reads bytes into an array from the stream. The current position is advanced.

Specified by:

readBytes in interface BasicInput

Parameters:

bbuf - array into which the bytes are read; the number of bytes read is the length of the array

Throws:

IOException

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

skip

public void skip(long nbytes)
          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:

nbytes - number of bytes to skip

Throws:

IOException

getOffset

public long getOffset()

Description copied from interface: BasicInput

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

Specified by:

getOffset in interface BasicInput

seek

public void seek(long offset)
          throws IOException

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:

IOException

close

public void close()
           throws IOException

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

Throws:

IOException