org.codelibs.elasticsearch.taste.common.iterator.FileLineIterator.java Source code

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Here is the source code for org.codelibs.elasticsearch.taste.common.iterator.FileLineIterator.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.codelibs.elasticsearch.taste.common.iterator;

import java.io.BufferedReader;
import java.io.Closeable;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.util.zip.GZIPInputStream;
import java.util.zip.ZipInputStream;

import org.codelibs.elasticsearch.taste.common.SkippingIterator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Charsets;
import com.google.common.collect.AbstractIterator;
import com.google.common.io.Closeables;
import com.google.common.io.Files;

/**
 * Iterates over the lines of a text file. This assumes the text file's lines are delimited in a manner
 * consistent with how {@link BufferedReader} defines lines.
 * <p/>
 * This class will uncompress files that end in .zip or .gz accordingly, too.
 */
public final class FileLineIterator extends AbstractIterator<String>
        implements SkippingIterator<String>, Closeable {

    private final BufferedReader reader;

    private static final Logger log = LoggerFactory.getLogger(FileLineIterator.class);

    /**
     * Creates a {@link FileLineIterator} over a given file, assuming a UTF-8 encoding.
     *
     * @throws java.io.FileNotFoundException if the file does not exist
     * @throws IOException
     *           if the file cannot be read
     */
    public FileLineIterator(File file) throws IOException {
        this(file, Charsets.UTF_8, false);
    }

    /**
     * Creates a {@link FileLineIterator} over a given file, assuming a UTF-8 encoding.
     *
     * @throws java.io.FileNotFoundException if the file does not exist
     * @throws IOException                   if the file cannot be read
     */
    public FileLineIterator(File file, boolean skipFirstLine) throws IOException {
        this(file, Charsets.UTF_8, skipFirstLine);
    }

    /**
     * Creates a {@link FileLineIterator} over a given file, using the given encoding.
     *
     * @throws java.io.FileNotFoundException if the file does not exist
     * @throws IOException                   if the file cannot be read
     */
    public FileLineIterator(File file, Charset encoding, boolean skipFirstLine) throws IOException {
        this(getFileInputStream(file), encoding, skipFirstLine);
    }

    public FileLineIterator(InputStream is) throws IOException {
        this(is, Charsets.UTF_8, false);
    }

    public FileLineIterator(InputStream is, boolean skipFirstLine) throws IOException {
        this(is, Charsets.UTF_8, skipFirstLine);
    }

    public FileLineIterator(InputStream is, Charset encoding, boolean skipFirstLine) throws IOException {
        reader = new BufferedReader(new InputStreamReader(is, encoding));
        if (skipFirstLine) {
            reader.readLine();
        }
    }

    public FileLineIterator(InputStream is, Charset encoding, boolean skipFirstLine, String filename)
            throws IOException {
        InputStream compressedInputStream;

        if ("gz".equalsIgnoreCase(Files.getFileExtension(filename.toLowerCase()))) {
            compressedInputStream = new GZIPInputStream(is);
        } else if ("zip".equalsIgnoreCase(Files.getFileExtension(filename.toLowerCase()))) {
            compressedInputStream = new ZipInputStream(is);
        } else {
            compressedInputStream = is;
        }

        reader = new BufferedReader(new InputStreamReader(compressedInputStream, encoding));
        if (skipFirstLine) {
            reader.readLine();
        }
    }

    static InputStream getFileInputStream(File file) throws IOException {
        InputStream is = new FileInputStream(file);
        String name = file.getName();
        if ("gz".equalsIgnoreCase(Files.getFileExtension(name.toLowerCase()))) {
            return new GZIPInputStream(is);
        } else if ("zip".equalsIgnoreCase(Files.getFileExtension(name.toLowerCase()))) {
            return new ZipInputStream(is);
        } else {
            return is;
        }
    }

    @Override
    protected String computeNext() {
        String line;
        try {
            line = reader.readLine();
        } catch (IOException ioe) {
            try {
                close();
            } catch (IOException e) {
                log.error(e.getMessage(), e);
            }
            throw new IllegalStateException(ioe);
        }
        return line == null ? endOfData() : line;
    }

    @Override
    public void skip(int n) {
        try {
            for (int i = 0; i < n; i++) {
                if (reader.readLine() == null) {
                    break;
                }
            }
        } catch (IOException ioe) {
            try {
                close();
            } catch (IOException e) {
                throw new IllegalStateException(e);
            }
        }
    }

    @Override
    public void close() throws IOException {
        endOfData();
        Closeables.close(reader, true);
    }

}