checkpointutils.java

这是个爬虫和lucece相结合最好了

/* CheckpointUtils
 *
 * $Id: CheckpointUtils.java 4658 2006-09-25 22:40:19Z paul_jack $
 *
 * Created on December 16, 2005.
 *
 * Copyright (C) 2005 Internet Archive.
 *
 * This file is part of the Heritrix web crawler (crawler.archive.org).
 *
 * Heritrix is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * any later version.
 *
 * Heritrix 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 Public License for more details.
 *
 * You should have received a copy of the GNU Lesser Public License
 * along with Heritrix; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package org.archive.crawler.util;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

/**
 * Utilities useful checkpointing.
 * @author stack
 * @version $Date: 2006-09-25 22:40:19 +0000 (Mon, 25 Sep 2006) $ $Revision: 4658 $
 */
public class CheckpointUtils {
    public static final String SERIALIZED_CLASS_SUFFIX = ".serialized";
    
    public static File getBdbSubDirectory(File checkpointDir) {
        return new File(checkpointDir, "bdbje-logs");
    }
    
    public static File getClassCheckpointFile(File checkpointDir,
            final String suffix, Class c) {
        return new File(checkpointDir, getClassCheckpointFilename(c, suffix));
    }
    
    public static File getClassCheckpointFile(File checkpointDir, Class c) {
        return new File(checkpointDir, getClassCheckpointFilename(c, null));
    }
    
    public static String getClassCheckpointFilename(final Class c) {
        return getClassCheckpointFilename(c, null);
    }
    
    public static String getClassCheckpointFilename(final Class c,
            final String suffix) {
        return c.getName() + ((suffix == null)? "": "." + suffix) +
            SERIALIZED_CLASS_SUFFIX;
    }
    
    /**
     * Utility function to serialize an object to a file in current checkpoint
     * dir. Facilities
     * to store related files alongside the serialized object in a directory
     * named with a <code>.auxillary</code> suffix.
     *
     * @param o Object to serialize.
     * @param dir Directory to serialize into.
     * @throws IOException
     */
    public static void writeObjectToFile(final Object o, final File dir)
    throws IOException {
        writeObjectToFile(o, null, dir);
    }
        
    public static void writeObjectToFile(final Object o, final String suffix,
            final File dir)
    throws IOException {
        dir.mkdirs();
        ObjectOutputStream out = new ObjectOutputStream(
            new FileOutputStream(getClassCheckpointFile(dir, suffix,
                o.getClass())));
        try {
            out.writeObject(o);
        } finally {
            out.close();
        }
    }
    
    public static <T> T readObjectFromFile(final Class<T> c, final File dir)
    throws FileNotFoundException, IOException, ClassNotFoundException {
        return readObjectFromFile(c, null, dir);
    }
    
    public static <T> T readObjectFromFile(final Class<T> c, final String suffix,
            final File dir)
    throws FileNotFoundException, IOException, ClassNotFoundException {
        ObjectInputStream in = new ObjectInputStream(
            new FileInputStream(getClassCheckpointFile(dir, suffix, c)));
        T o = null;
        try {
            o = c.cast(in.readObject());
        } finally {
            in.close();
        }
        return o;
    }

    /**
     * @return Instance of filename filter that will let through files ending
     * in '.jdb' (i.e. bdb je log files).
     */
    public static FilenameFilter getJeLogsFilter() {
        return new FilenameFilter() {
            public boolean accept(File dir, String name) {
                return name != null && name.toLowerCase().endsWith(".jdb");
            }
        };
    }
}