/**
* @author : Paul Taylor
* @author : Eric Farng
*
* Version @version:$Id: AbstractID3v2FrameBody.java 976 2011-06-08 10:05:34Z paultaylor $
*
* MusicTag Copyright (C)2003,2004
*
* This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser
* General Public License as published by the Free Software Foundation; either version 2.1 of the License,
* or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
* the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License along with this library; if not,
* you can get a copy from http://www.opensource.org/licenses/lgpl-license.php or write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Description:
* Abstract Superclass of all Frame Bodys
*
*/
package org.jaudiotagger.tag.id3.framebody;
import org.jaudiotagger.audio.mp3.MP3File;
import org.jaudiotagger.tag.InvalidDataTypeException;
import org.jaudiotagger.tag.InvalidFrameException;
import org.jaudiotagger.tag.InvalidTagException;
import org.jaudiotagger.tag.datatype.AbstractDataType;
import org.jaudiotagger.tag.id3.AbstractTagFrameBody;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
/**
* Contains the content for an ID3v2 frame, (the header is held directly within the frame
*/
public abstract class AbstractID3v2FrameBody extends AbstractTagFrameBody
{
protected static final String TYPE_BODY = "body";
/**
* Frame Body Size, originally this is size as indicated in frame header
* when we come to writing data we recalculate it.
*/
private int size;
/**
* Create Empty Body. Super Constructor sets up Object list
*/
protected AbstractID3v2FrameBody()
{
}
/**
* Create Body based on another body
* @param copyObject
*/
protected AbstractID3v2FrameBody(AbstractID3v2FrameBody copyObject)
{
super(copyObject);
}
/**
* Creates a new FrameBody dataType from file. The super
* Constructor sets up the Object list for the frame.
*
* @param byteBuffer from where to read the frame body from
* @param frameSize
* @throws org.jaudiotagger.tag.InvalidTagException
*/
protected AbstractID3v2FrameBody(ByteBuffer byteBuffer, int frameSize) throws InvalidTagException
{
super();
setSize(frameSize);
this.read(byteBuffer);
}
/**
* Return the ID3v2 Frame Identifier, must be implemented by concrete subclasses
*
* @return the frame identifier
*/
public abstract String getIdentifier();
/**
* Return size of frame body,if frameBody already exist will take this value from the frame header
* but it is always recalculated before writing any changes back to disk.
*
* @return size in bytes of this frame body
*/
public int getSize()
{
return size;
}
/**
* Set size based on size passed as parameter from frame header,
* done before read
* @param size
*/
public void setSize(int size)
{
this.size = size;
}
/**
* Set size based on size of the DataTypes making up the body,done after write
*/
public void setSize()
{
size = 0;
for (AbstractDataType object : objectList)
{
size += object.getSize();
}
}
/**
* Are two bodies equal
*
* @param obj
*/
public boolean equals(Object obj)
{
return (obj instanceof AbstractID3v2FrameBody) && super.equals(obj);
}
/**
* This reads a frame body from a ByteBuffer into the appropriate FrameBody class and update the position of the
* buffer to be just after the end of this frameBody
* <p/>
* The ByteBuffer represents the tag and its position should be at the start of this frameBody. The size as
* indicated in the header is passed to the frame constructor when reading from file.
*
* @param byteBuffer file to read
* @throws InvalidFrameException if unable to construct a frameBody from the ByteBuffer
*/
//TODO why don't we just slice byteBuffer, set limit to size and convert readByteArray to take a ByteBuffer
//then we wouldn't have to temporary allocate space for the buffer, using lots of needless memory
//and providing extra work for the garbage collector.
public void read(ByteBuffer byteBuffer) throws InvalidTagException
{
int size = getSize();
logger.config("Reading body for" + this.getIdentifier() + ":" + size);
//Allocate a buffer to the size of the Frame Body and read from file
byte[] buffer = new byte[size];
byteBuffer.get(buffer);
//Offset into buffer, incremented by length of previous dataType
//this offset is only used internally to decide where to look for the next
//dataType within a frameBody, it does not decide where to look for the next frame body
int offset = 0;
//Go through the ObjectList of the Frame reading the data into the
for (AbstractDataType object : objectList)
//correct dataType.
{
logger.finest("offset:" + offset);
//The read has extended further than the defined frame size (ok to extend upto
//size because the next datatype may be of length 0.)
if (offset > (size))
{
logger.warning("Invalid Size for FrameBody");
throw new InvalidFrameException("Invalid size for Frame Body");
}
//Try and load it with data from the Buffer
//if it fails frame is invalid
try
{
object.readByteArray(buffer, offset);
}
catch (InvalidDataTypeException e)
{
logger.warning("Problem reading datatype within Frame Body:" + e.getMessage());
throw e;
}
//Increment Offset to start of next datatype.
offset += object.getSize();
}
}
/**
* Write the contents of this datatype to the byte array
*
* @param tagBuffer
* @throws IOException on any I/O error
*/
public void write(ByteArrayOutputStream tagBuffer)
{
logger.config("Writing frame body for" + this.getIdentifier() + ":Est Size:" + size);
//Write the various fields to file in order
for (AbstractDataType object : objectList)
{
byte[] objectData = object.writeByteArray();
if (objectData != null)
{
try
{
tagBuffer.write(objectData);
}
catch (IOException ioe)
{
//This could never happen coz not writing to file, so convert to RuntimeException
throw new RuntimeException(ioe);
}
}
}
setSize();
logger.config("Written frame body for" + this.getIdentifier() + ":Real Size:" + size);
}
/**
* Return String Representation of Datatype *
*/
public void createStructure()
{
MP3File.getStructureFormatter().openHeadingElement(TYPE_BODY, "");
for (AbstractDataType nextObject : objectList)
{
nextObject.createStructure();
}
MP3File.getStructureFormatter().closeHeadingElement(TYPE_BODY);
}
}
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