com.google.cloud.dataflow.sdk.util.FileIOChannelFactory.java Source code

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Here is the source code for com.google.cloud.dataflow.sdk.util.FileIOChannelFactory.java

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/*
 * Copyright (C) 2015 Google Inc.
 *
 * 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.google.cloud.dataflow.sdk.util;

import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.Iterables;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
import java.nio.channels.WritableByteChannel;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.NoSuchFileException;
import java.nio.file.PathMatcher;
import java.nio.file.Paths;
import java.util.Collection;
import java.util.LinkedList;
import java.util.List;
import java.util.regex.Matcher;

/**
 * Implements IOChannelFactory for local files.
 */
public class FileIOChannelFactory implements IOChannelFactory {
    private static final Logger LOG = LoggerFactory.getLogger(FileIOChannelFactory.class);

    // This implementation only allows for wildcards in the file name.
    // The directory portion must exist as-is.
    @Override
    public Collection<String> match(String spec) throws IOException {
        File file = new File(spec);

        File parent = file.getAbsoluteFile().getParentFile();
        if (!parent.exists()) {
            throw new IOException("Unable to find parent directory of " + spec);
        }

        // Method getAbsolutePath() on Windows platform may return something like
        // "c:\temp\file.txt". FileSystem.getPathMatcher() call below will treat
        // '\' (backslash) as an escape character, instead of a directory
        // separator. Replacing backslash with double-backslash solves the problem.
        // We perform the replacement on all platforms, even those that allow
        // backslash as a part of the filename, because Globs.toRegexPattern will
        // eat one backslash.
        String pathToMatch = file.getAbsolutePath().replaceAll(Matcher.quoteReplacement("\\"),
                Matcher.quoteReplacement("\\\\"));

        final PathMatcher matcher = FileSystems.getDefault().getPathMatcher("glob:" + pathToMatch);

        Iterable<File> files = com.google.common.io.Files.fileTreeTraverser().preOrderTraversal(parent);
        Iterable<File> matchedFiles = Iterables.filter(files,
                Predicates.and(com.google.common.io.Files.isFile(), new Predicate<File>() {
                    @Override
                    public boolean apply(File input) {
                        return matcher.matches(input.toPath());
                    }
                }));

        List<String> result = new LinkedList<>();
        for (File match : matchedFiles) {
            result.add(match.getPath());
        }

        return result;
    }

    @Override
    public ReadableByteChannel open(String spec) throws IOException {
        LOG.debug("opening file {}", spec);
        @SuppressWarnings("resource") // The caller is responsible for closing the channel.
        FileInputStream inputStream = new FileInputStream(spec);
        // Use this method for creating the channel (rather than new FileChannel) so that we get
        // regular FileNotFoundException. Closing the underyling channel will close the inputStream.
        return inputStream.getChannel();
    }

    @Override
    public WritableByteChannel create(String spec, String mimeType) throws IOException {
        LOG.debug("creating file {}", spec);
        File file = new File(spec);
        if (file.getAbsoluteFile().getParentFile() != null && !file.getAbsoluteFile().getParentFile().exists()
                && !file.getAbsoluteFile().getParentFile().mkdirs()
                && !file.getAbsoluteFile().getParentFile().exists()) {
            throw new IOException("Unable to create parent directories for '" + spec + "'");
        }
        return Channels.newChannel(new BufferedOutputStream(new FileOutputStream(file)));
    }

    @Override
    public long getSizeBytes(String spec) throws IOException {
        try {
            return Files.size(FileSystems.getDefault().getPath(spec));
        } catch (NoSuchFileException e) {
            throw new FileNotFoundException(e.getReason());
        }
    }

    @Override
    public boolean isReadSeekEfficient(String spec) throws IOException {
        return true;
    }

    @Override
    public String resolve(String path, String other) throws IOException {
        return Paths.get(path).resolve(other).toString();
    }
}