Package com.drew.lang

Class ByteArrayReader

java.lang.Object

com.drew.lang.RandomAccessReader

com.drew.lang.ByteArrayReader

public class ByteArrayReader
extends RandomAccessReader

Provides methods to read specific values from a byte array, with a consistent, checked exception structure for issues.

By default, the reader operates with Motorola byte order (big endianness). This can be changed by calling setMotorolaByteOrder(boolean).

Field Summary

Fields

Modifier and Type	Field	Description
private int	_baseOffset
private byte[]	_buffer

Constructor Summary

Constructors

Constructor	Description
ByteArrayReader(byte[] buffer)
ByteArrayReader(byte[] buffer, int baseOffset)

Method Summary

Modifier and Type	Method	Description
byte	getByte(int index)	Gets the byte value at the specified byte index.
byte[]	getBytes(int index, int count)	Returns the required number of bytes from the specified index from the underlying source.
long	getLength()	Returns the length of the data source in bytes.
protected boolean	isValidIndex(int index, int bytesRequested)
int	toUnshiftedOffset(int localOffset)
protected void	validateIndex(int index, int bytesRequested)	Ensures that the buffered bytes extend to cover the specified index.

Methods inherited from class com.drew.lang.RandomAccessReader

getBit, getDouble64, getFloat32, getInt16, getInt24, getInt32, getInt64, getInt8, getNullTerminatedBytes, getNullTerminatedString, getNullTerminatedStringValue, getS15Fixed16, getString, getString, getStringValue, getUInt16, getUInt32, getUInt8, isMotorolaByteOrder, setMotorolaByteOrder

Methods inherited from class java.lang.Object

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

Field Detail

_buffer

private final byte[] _buffer

_baseOffset

private final int _baseOffset

Constructor Detail

ByteArrayReader

public ByteArrayReader(byte[] buffer)

ByteArrayReader

public ByteArrayReader(byte[] buffer,
                       int baseOffset)

Method Detail

toUnshiftedOffset

public int toUnshiftedOffset(int localOffset)

Specified by:

toUnshiftedOffset in class RandomAccessReader

getLength

public long getLength()

Description copied from class: RandomAccessReader

Returns the length of the data source in bytes.

This is a simple operation for implementations (such as RandomAccessFileReader and ByteArrayReader) that have the entire data source available.

Users of this method must be aware that sequentially accessed implementations such as RandomAccessStreamReader will have to read and buffer the entire data source in order to determine the length.

Specified by:

getLength in class RandomAccessReader

Returns:

the length of the data source, in bytes.

getByte

public byte getByte(int index)
             throws java.io.IOException

Description copied from class: RandomAccessReader

Gets the byte value at the specified byte index.

Implementations should not perform any bounds checking in this method. That should be performed in validateIndex and isValidIndex.

Specified by:

getByte in class RandomAccessReader

Parameters:

index - The index from which to read the byte

Returns:

The read byte value

Throws:

BufferBoundsException - if the requested byte is beyond the end of the underlying data source

java.io.IOException - if the byte is unable to be read

validateIndex

protected void validateIndex(int index,
                             int bytesRequested)
                      throws java.io.IOException

Description copied from class: RandomAccessReader

Ensures that the buffered bytes extend to cover the specified index. If not, an attempt is made to read to that point.

If the stream ends before the point is reached, a BufferBoundsException is raised.

Specified by:

validateIndex in class RandomAccessReader

Parameters:

index - the index from which the required bytes start

bytesRequested - the number of bytes which are required

Throws:

java.io.IOException - if the stream ends before the required number of bytes are acquired

isValidIndex

protected boolean isValidIndex(int index,
                               int bytesRequested)
                        throws java.io.IOException

Specified by:

isValidIndex in class RandomAccessReader

Throws:

java.io.IOException

getBytes

public byte[] getBytes(int index,
                       int count)
                throws java.io.IOException

Description copied from class: RandomAccessReader

Returns the required number of bytes from the specified index from the underlying source.

Specified by:

getBytes in class RandomAccessReader

Parameters:

index - The index from which the bytes begins in the underlying source

count - The number of bytes to be returned

Returns:

The requested bytes

Throws:

BufferBoundsException - if the requested bytes extend beyond the end of the underlying data source

java.io.IOException - if the byte is unable to be read