CentralEnd.java

/*
 * Copyright (C) 2010 Ken Ellinwood
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package kellinwood.zipio;

import java.io.IOException;

import kellinwood.logging.LoggerInterface;
import kellinwood.logging.LoggerManager;

public class CentralEnd 
{
    public int signature = 0x06054b50; // end of central dir signature    4 bytes
    public short numberThisDisk = 0;   // number of this disk             2 bytes     
    public short centralStartDisk = 0; // number of the disk with the start of the central directory  2 bytes
    public short numCentralEntries;    // total number of entries in the central directory on this disk  2 bytes
    public short totalCentralEntries;  // total number of entries in the central directory           2 bytes

    public int centralDirectorySize;   // size of the central directory   4 bytes
    public int centralStartOffset;     // offset of start of central directory with respect to the starting disk number        4 bytes
    public String fileComment;         // .ZIP file comment       (variable size)

    private static LoggerInterface log;

    public static CentralEnd read(ZipInput input) throws IOException
    {

        int signature = input.readInt();
        if (signature != 0x06054b50) {
            // back up to the signature
            input.seek( input.getFilePointer() - 4);
            return null;
        }

        CentralEnd entry = new CentralEnd();

        entry.doRead( input);
        return entry;
    }

    public static LoggerInterface getLogger() {
        if (log == null) log = LoggerManager.getLogger( CentralEnd.class.getName());
        return log;
    }


    private void doRead( ZipInput input) throws IOException
    {

        boolean debug = getLogger().isDebugEnabled();

        numberThisDisk = input.readShort();
        if (debug) log.debug( String.format("This disk number: 0x%04x", numberThisDisk));

        centralStartDisk = input.readShort();
        if (debug) log.debug( String.format("Central dir start disk number: 0x%04x", centralStartDisk));

        numCentralEntries = input.readShort();
        if (debug) log.debug( String.format("Central entries on this disk: 0x%04x", numCentralEntries));

        totalCentralEntries = input.readShort();
        if (debug) log.debug( String.format("Total number of central entries: 0x%04x", totalCentralEntries));

        centralDirectorySize = input.readInt();
        if (debug) log.debug( String.format("Central directory size: 0x%08x", centralDirectorySize));

        centralStartOffset = input.readInt();
        if (debug) log.debug( String.format("Central directory offset: 0x%08x", centralStartOffset));

        short zipFileCommentLen = input.readShort();
        fileComment = input.readString(zipFileCommentLen);
        if (debug) log.debug( ".ZIP file comment: " + fileComment);


    }


    public void write( ZipOutput output) throws IOException
    {

        boolean debug = getLogger().isDebugEnabled();

        output.writeInt( signature);
        output.writeShort( numberThisDisk);
        output.writeShort( centralStartDisk);
        output.writeShort( numCentralEntries);
        output.writeShort( totalCentralEntries);
        output.writeInt( centralDirectorySize );
        output.writeInt( centralStartOffset );
        output.writeShort( (short)fileComment.length());
        output.writeString( fileComment);


    }

}