com.drew.metadata.jpeg
Class JpegReader

java.lang.Object
  com.drew.metadata.jpeg.JpegReader

All Implemented Interfaces:

MetadataReader

public class JpegReader
extends Object
implements MetadataReader

Decodes Jpeg SOF0 data, populating a Metadata object with tag values in a JpegDirectory.

Author:

Darrell Silver http://www.darrellsilver.com and Drew Noakes

Field Summary

private byte[]

_data The SOF0 data segment.

Constructor Summary

JpegReader(byte[] data)
Creates a JpegReader for a byte[] containing JPEG data.

JpegReader(File jpegFile)
Creates a new JpegReader for the specified Jpeg jpegFile.

JpegReader(InputStream is)
Creates a JpegReader for a JPEG stream.

Method Summary

Metadata	extract() Performs the Jpeg data extraction, returning a new instance of Metadata.
Metadata	extract(Metadata metadata) Performs the Jpeg data extraction, adding found values to the specified instance of Metadata.
private int	get16Bits(int offset) Returns an int calculated from one byte of data at the specified offset.
private int	get32Bits(int offset) Returns an int calculated from two bytes of data at the specified offset (MSB, LSB).

Methods inherited from class java.lang.Object

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

Field Detail

_data

private final byte[] _data

The SOF0 data segment.

Constructor Detail

JpegReader

public JpegReader(File jpegFile)
           throws JpegProcessingException

Creates a new JpegReader for the specified Jpeg jpegFile.

Throws:

JpegProcessingException

JpegReader

public JpegReader(InputStream is)
           throws JpegProcessingException

Creates a JpegReader for a JPEG stream.

Parameters:

is - JPEG stream. Stream will be closed.

Throws:

JpegProcessingException

JpegReader

public JpegReader(byte[] data)

Creates a JpegReader for a byte[] containing JPEG data.

Parameters:

data - the contents of an entire JPEG file as a byte[]

Method Detail

extract

public Metadata extract()

Performs the Jpeg data extraction, returning a new instance of Metadata.

Specified by:

extract in interface MetadataReader

Returns:

The populated Metadata object.

extract

public Metadata extract(Metadata metadata)

Performs the Jpeg data extraction, adding found values to the specified instance of Metadata.

Specified by:

extract in interface MetadataReader

Returns:

The updated Metadata object.

get32Bits

private int get32Bits(int offset)
               throws MetadataException

Returns an int calculated from two bytes of data at the specified offset (MSB, LSB).

Parameters:

offset - position within the data buffer to read first byte

Returns:

the 32 bit int value, between 0x0000 and 0xFFFF

Throws:

MetadataException

get16Bits

private int get16Bits(int offset)
               throws MetadataException

Returns an int calculated from one byte of data at the specified offset.

Parameters:

offset - position within the data buffer to read byte

Returns:

the 16 bit int value, between 0x00 and 0xFF

Throws:

MetadataException