tailfilter.java

java编写的OCR软件

package de.spieleck.app.jacson.filter;

import de.spieleck.config.ConfigNode;
import de.spieleck.config.ConfigVerify.Acceptor;

import de.spieleck.app.jacson.JacsonException;
import de.spieleck.app.jacson.JacsonConfigException;
import de.spieleck.app.jacson.JacsonRegistry;
import de.spieleck.app.jacson.util.ConfigUtil;

/**
 * Block all chunks of a stream, all but the last ones.
 * This is an example for a Filter, acting upon a chunk = null.
 * The usage of this filter renders JacsonState.chunkNo() useless
 * in all later stages of processing.
 * @author fsn
 */
public class TailFilter
    extends FilterBase
    implements FilterNames, Acceptor
{
    /** Cyclical buffer for the last chunks seen. */
    String[] trail;

    /** Current position in the cyclical buffer. */
    protected int pos;

    public void init(ConfigNode config, JacsonRegistry registry)
        throws JacsonConfigException
    {
        int tail = config.getInt(COUNT_NODE, -1);
        if ( tail < 0 )
            throw new JacsonConfigException("HeadFilter needs count > 0");
        trail = new String[tail];
        pos = 0;
        ConfigUtil.verify(config, this);
    }
  
    public boolean accept(ConfigNode node)
    {
        String name = node.getName();
        return COUNT_NODE.equals(name);
    }

    public void putChunk(String chunk)
        throws JacsonException
    {
        if ( chunk == null )
        {
            for(int i = Math.max(0, pos- trail.length); i < pos; i++)
            {
                drain.putChunk(trail[i %  trail.length]);
            }
            drain.putChunk(null);
        }
        else 
        {
            trail[ pos++ %  trail.length ] = chunk;
        }
    }
}
//
//    Jacson - Text Filtering with Java.
//    Copyright (C) 2002 Frank S. Nestel (nestefan -at- users.sourceforge.net)
//
//    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, write to the Free Software
//    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//