abstractlyrics3v2fieldframebody.java

java+eclipse做的TTPlayer

/**
 *  @author : Paul Taylor
 *  @author : Eric Farng
 *
 *  Version @version:$Id: AbstractLyrics3v2FieldFrameBody.java,v 1.8 2007/08/07 14:36:16 paultaylor Exp $
 *
 *  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:
 */
package com.hadeslee.audiotag.tag.lyrics3;

import com.hadeslee.audiotag.tag.id3.AbstractTagFrameBody;
import com.hadeslee.audiotag.tag.InvalidTagException;
import com.hadeslee.audiotag.tag.TagOptionSingleton;
import com.hadeslee.audiotag.tag.datatype.AbstractDataType;

import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.util.Iterator;

public abstract class AbstractLyrics3v2FieldFrameBody extends AbstractTagFrameBody
{
    public AbstractLyrics3v2FieldFrameBody()
    {
    }

    public AbstractLyrics3v2FieldFrameBody(AbstractLyrics3v2FieldFrameBody copyObject)
    {
        super(copyObject);
    }

    /**
     * This is called by superclass when attempt to read data from file.
     *
     * @param file 
     * @return 
     * @throws InvalidTagException 
     * @throws IOException         
     */
    protected int readHeader(RandomAccessFile file)
        throws InvalidTagException, IOException
    {
        int size;
        byte[] buffer = new byte[5];

        // read the 5 character size
        file.read(buffer, 0, 5);
        size = Integer.parseInt(new String(buffer, 0, 5));

        if ((size == 0) && (TagOptionSingleton.getInstance().isLyrics3KeepEmptyFieldIfRead() == false))
        {
            throw new InvalidTagException("Lyircs3v2 Field has size of zero.");
        }

        return size;
    }

    /**
     * This is called by superclass when attempt to write data from file.
     *
     * @param file 
     * @param size 
     * @throws IOException 
     */
    protected void writeHeader(RandomAccessFile file, int size)
        throws IOException
    {
        String str;
        int offset = 0;
        byte[] buffer = new byte[5];

        /**
         * @todo change this to use pad String
         */
        str = Integer.toString(getSize());

        for (int i = 0; i < (5 - str.length()); i++)
        {
            buffer[i] = (byte) '0';
        }

        offset += (5 - str.length());

        for (int i = 0; i < str.length(); i++)
        {
            buffer[i + offset] = (byte) str.charAt(i);
        }

        file.write(buffer);
    }

    /**
     * This reads a frame body from its file into the appropriate FrameBody class
     * Read the data from the given file into this datatype. The file needs to
     * have its file pointer in the correct location. The size as indicated in the
     * header is passed to the frame constructor when reading from file.
     *
     * @param byteBuffer file to read
     * @throws IOException         on any I/O error
     * @throws InvalidTagException if there is any error in the data format.
     */
    public void read(ByteBuffer byteBuffer) throws InvalidTagException
    {
        int size = getSize();
        //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 MP3Object
        int offset = 0;

        //Go through the ObjectList of the Frame reading the data into the
        //correct datatype.
        AbstractDataType object;
        Iterator iterator = objectList.listIterator();
        while (iterator.hasNext())
        {
            //The read has extended further than the defined frame size
            if (offset > (size - 1))
            {
                throw new InvalidTagException("Invalid size for Frame Body");
            }

            //Get next Object and load it with data from the Buffer
            object = (AbstractDataType) iterator.next();
            object.readByteArray(buffer, offset);
            //Increment Offset to start of next datatype.
            offset += object.getSize();
        }
    }

    /**
     * Write the contents of this datatype to the file at the position it is
     * currently at.
     *
     * @param file destination file
     * @throws IOException on any I/O error
     */
    public void write(RandomAccessFile file)
        throws IOException
    {
        //Write the various fields to file in order
        byte[] buffer;
        AbstractDataType object;
        Iterator iterator = objectList.listIterator();
        while (iterator.hasNext())
        {
            object = (AbstractDataType) iterator.next();
            buffer = object.writeByteArray();
            file.write(buffer);
        }
    }

}