com.googlecode.jweb1t.IndexCreator.java Source code

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Here is the source code for com.googlecode.jweb1t.IndexCreator.java

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/*
 * Copyright 2007 FBK-irst http://www.itc.it/)
 *
 * 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 com.googlecode.jweb1t;

import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.LineNumberReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.io.IOUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Creates an index showing which ngrams (indexed by the first two characters) are to be found in which files on the disk.
 * 
 * @author Claudio Giuliano
 */
public class IndexCreator {
    private final Log logger = LogFactory.getLog(this.getClass());

    private final Map<String, List<File>> map;

    private final File baseDir;

    public IndexCreator(final File aBaseDir, final String aNGramSize) throws IOException {
        map = new HashMap<String, List<File>>();

        baseDir = aBaseDir;

        final File ngramFile = new File(aBaseDir + "/" + aNGramSize + "gms/");
        final File indexFile = new File(aBaseDir + "/" + "index-" + aNGramSize + "gms");

        if (ngramFile.isFile()) {
            read(ngramFile);
        } else {
            final FolderScanner scanner = new FolderScanner(ngramFile);
            scanner.setFilter(new IndexFilter());

            int count = 0;
            while (scanner.hasNext()) {
                final File[] files = scanner.next();
                logger.info((count++) + " : " + files.length);
                for (int i = 0; i < files.length; i++) {
                    final long begin = System.currentTimeMillis();
                    read(files[i]);

                    final long end = System.currentTimeMillis();
                    logger.info(count + ", " + files[i] + " read in " + (end - begin) + " ms");
                    count++;
                }
            }
        }

        write(indexFile);
    }

    private void write(final File outputFile) throws IOException {
        PrintWriter writer = null;

        try {
            writer = new PrintWriter(new FileWriter(outputFile));

            for (final String ch : map.keySet()) {
                final List<File> fileList = map.get(ch);
                writer.print(ch);
                for (final File file : fileList) {
                    // store only the path relative to the index file
                    final String relative = baseDir.toURI().relativize(file.toURI()).getPath();
                    writer.print("\t" + relative);
                }
                writer.print("\n");
            }
            writer.flush();
        } finally {
            IOUtils.closeQuietly(writer);
        }
    }

    private void read(final File aFile) throws IOException {
        LineNumberReader reader = null;
        try {
            reader = new LineNumberReader(new FileReader(aFile));
            String line = null;
            String ch = null;

            // first line
            if ((line = reader.readLine()) != null) {
                ch = line.substring(0, 2).trim();
            }

            String old = ch;

            // second line
            while ((line = reader.readLine()) != null) {
                ch = line.substring(0, 2).trim();

                if (!ch.equals(old)) {
                    put(old, aFile);
                    old = ch;
                }
            }

            put(old, aFile);
        } finally {
            IOUtils.closeQuietly(reader);
        }
    }

    private void put(final String ch, final File aFile) {
        List<File> fileList = map.get(ch);

        if (fileList == null) {
            fileList = new ArrayList<File>();
            fileList.add(aFile);
            map.put(ch, fileList);
            return;
        }

        fileList.add(aFile);
    }
}