Package gov.nasa.pds.objectAccess

Class ByteWiseFileAccessor

java.lang.Object

gov.nasa.pds.objectAccess.ByteWiseFileAccessor

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class ByteWiseFileAccessor
extends java.lang.Object
implements java.io.Closeable

Class that provides common I/O functionality for PDS data objects.

Constructor Summary

Constructors

Constructor	Description
ByteWiseFileAccessor(java.io.File file, long offset, int length, long records)	Constructs a ByteWiseFileAccessor object which maps a region of a data file into memory.
ByteWiseFileAccessor(java.net.URL url, long offset, int length, long records)	Constructs a ByteWiseFileAccessor object which maps a region of a data file into memory.
ByteWiseFileAccessor(java.net.URL url, long offset, int length, long records, boolean checkSize)
ByteWiseFileAccessor(java.net.URL url, long offset, int length, long records, boolean checkSize, java.io.RandomAccessFile raf)	Constructs a ByteWiseFileAccessor object which maps a region of a data file into memory.

Method Summary

Modifier and Type	Method	Description
void	close()
long	getCurrentPosition()
java.io.RandomAccessFile	getRandomAccessFile()
long	getTotalBytesRead()
long	getTotalFileContentSize()
boolean	hasRemaining()	Checks to see if the buffer can still be read.
void	mark()	Marks the buffer.
byte	readByte()	Reads a byte from the buffer.
byte[]	readRecordBytes(long recordNum, int offset, int length)	Reads length bytes of data from a specified record at the given offset.
void	reset()	Resets the buffer.

Methods inherited from class java.lang.Object

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

Constructor Detail

ByteWiseFileAccessor

public ByteWiseFileAccessor(java.io.File file,
                            long offset,
                            int length,
                            long records)
                     throws java.io.FileNotFoundException,
                            java.io.IOException,
                            InvalidTableException

Constructs a ByteWiseFileAccessor object which maps a region of a data file into memory.

Parameters:

file - the data file

offset - the offset within the data file

length - the record length in bytes

records - the number of records

Throws:

java.io.FileNotFoundException - If file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading

java.io.IOException - If an I/O error occurs

InvalidTableException

MissingDataException

java.lang.IllegalArgumentException

ByteWiseFileAccessor

public ByteWiseFileAccessor(java.net.URL url,
                            long offset,
                            int length,
                            long records)
                     throws java.io.FileNotFoundException,
                            java.io.IOException,
                            InvalidTableException

Constructs a ByteWiseFileAccessor object which maps a region of a data file into memory.

Parameters:

url - the data file

offset - the offset within the data file

length - the record length in bytes

records - the number of records

Throws:

java.io.FileNotFoundException - If file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading

java.io.IOException - If an I/O error occurs

InvalidTableException

MissingDataException

java.lang.IllegalArgumentException

ByteWiseFileAccessor

public ByteWiseFileAccessor(java.net.URL url,
                            long offset,
                            int length,
                            long records,
                            boolean checkSize)
                     throws java.io.FileNotFoundException,
                            java.io.IOException,
                            InvalidTableException

Throws:

java.io.FileNotFoundException

java.io.IOException

InvalidTableException

ByteWiseFileAccessor

public ByteWiseFileAccessor(java.net.URL url,
                            long offset,
                            int length,
                            long records,
                            boolean checkSize,
                            java.io.RandomAccessFile raf)
                     throws java.io.FileNotFoundException,
                            java.io.IOException,
                            InvalidTableException

Constructs a ByteWiseFileAccessor object which maps a region of a data file into memory.

Parameters:

url - the data file

offset - the offset within the data file

length - the record length in bytes

records - the number of records

checkSize - check that the size of the data file is equal to the size of the table (length * records) + offset.

Throws:

java.io.FileNotFoundException - If file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading

java.io.IOException - If an I/O error occurs

InvalidTableException

MissingDataException

Method Detail

readRecordBytes

public byte[] readRecordBytes(long recordNum,
                              int offset,
                              int length)

Reads length bytes of data from a specified record at the given offset.

Parameters:

recordNum - the record number to read bytes from (1-relative)

offset - an offset within the record

length - the number of bytes to read from the record

Returns:

an array of bytes

readByte

public byte readByte()

Reads a byte from the buffer.

Returns:

A byte.

mark

public void mark()

Marks the buffer.

reset

public void reset()

Resets the buffer.

hasRemaining

public boolean hasRemaining()

Checks to see if the buffer can still be read.

Returns:

'true' if there are more bytes to be read. 'false' otherwise.

getCurrentPosition

public long getCurrentPosition()

getTotalFileContentSize

public long getTotalFileContentSize()

getTotalBytesRead

public long getTotalBytesRead()

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

getRandomAccessFile

public java.io.RandomAccessFile getRandomAccessFile()