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A Java NIO file system provider for HDFS
There is a newer version: 1.0.3
/*
 * Copyright 2016 Damien Carol 
 *
 * 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 hdfs.jsr203;

import java.io.IOException;
import java.net.URI;
import java.nio.channels.FileChannel;
import java.nio.channels.SeekableByteChannel;
import java.nio.file.AccessMode;
import java.nio.file.CopyOption;
import java.nio.file.DirectoryStream;
import java.nio.file.DirectoryStream.Filter;
import java.nio.file.FileStore;
import java.nio.file.FileSystem;
import java.nio.file.FileSystemNotFoundException;
import java.nio.file.LinkOption;
import java.nio.file.OpenOption;
import java.nio.file.Path;
import java.nio.file.ProviderMismatchException;
import java.nio.file.attribute.BasicFileAttributes;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.FileAttributeView;
import java.nio.file.attribute.PosixFileAttributes;
import java.nio.file.spi.FileSystemProvider;
import java.util.Collections;
import java.util.Map;
import java.util.Set;

import org.apache.hadoop.fs.PathFilter;

/**
 * {@link FileSystemProvider} implementation for HDFS.
 * 
 * This provider implements the actual {@code META-INF/services/} entry.
 */
public class HadoopFileSystemProvider extends FileSystemProvider {
    public static final String SCHEME = "hdfs";

    // Copy-cat of
    // org.apache.hadoop.mapreduce.lib.input.FileInputFormat.hiddenFileFilter
    private static final PathFilter hiddenFileFilter = new PathFilter() {
        public boolean accept(org.apache.hadoop.fs.Path p) {
            String name = p.getName();
            return !name.startsWith("_") && !name.startsWith(".");
        }
    };

    // Checks that the given file is a HadoopPath
    static final HadoopPath toHadoopPath(Path path) {
        if (path == null) {
            throw new NullPointerException();
        }
        if (!(path instanceof HadoopPath)) {
            throw new ProviderMismatchException();
        }
        return (HadoopPath) path;
    }

    @Override
    public void checkAccess(Path path, AccessMode... modes) throws IOException {
        toHadoopPath(path).getFileSystem().checkAccess(toHadoopPath(path), modes);
    }

    @Override
    public void copy(Path source, Path target, CopyOption... options) throws IOException {
        toHadoopPath(source).copy(toHadoopPath(target), options);
    }

    @Override
    public void createDirectory(Path dir, FileAttribute... attrs) throws IOException {
        toHadoopPath(dir).createDirectory(attrs);
    }

    @Override
    public void delete(Path path) throws IOException {
        toHadoopPath(path).delete();
    }

    @Override
    public  V getFileAttributeView(Path path, Class type, LinkOption... options) {
        return toHadoopPath(path).getFileSystem().getView(toHadoopPath(path), type);
    }

    @Override
    public FileStore getFileStore(Path path) throws IOException {
        return toHadoopPath(path).getFileStore();
    }

    @Override
    public FileSystem getFileSystem(URI uri) {
        try {
            return newFileSystem(uri, Collections. emptyMap());
        } catch (IOException e) {
            throw new FileSystemNotFoundException(e.getMessage());
        }
    }

    @Override
    public Path getPath(URI uri) {
        return getFileSystem(uri).getPath(uri.getPath());
    }

    @Override
    public String getScheme() {
        return SCHEME;
    }

    @Override
    public boolean isHidden(Path path) throws IOException {
        return !hiddenFileFilter.accept(toHadoopPath(path).getRawResolvedPath());
    }

    @Override
    public boolean isSameFile(Path path, Path path2) throws IOException {
        return toHadoopPath(path).compareTo(toHadoopPath(path2)) == 0;
    }

    @Override
    public void move(Path source, Path target, CopyOption... options) throws IOException {
        toHadoopPath(source).move(toHadoopPath(target), options);
    }

    @Override
    public SeekableByteChannel newByteChannel(Path path, Set options, FileAttribute... attrs)
            throws IOException {
        return toHadoopPath(path).newByteChannel(options, attrs);
    }

    @Override
    public FileChannel newFileChannel(Path path, Set options, FileAttribute... attrs)
            throws IOException {
        return toHadoopPath(path).newFileChannel(options, attrs);
    }

    @Override
    public DirectoryStream newDirectoryStream(Path dir, Filter filter) throws IOException {
        return toHadoopPath(dir).newDirectoryStream(filter);
    }

    @Override
    public FileSystem newFileSystem(URI uri, Map env) throws IOException {
        return new HadoopFileSystem(this, uri.getHost(), uri.getPort());
    }

    @SuppressWarnings("unchecked")
    @Override
    public  A readAttributes(Path path, Class type, LinkOption... options)
            throws IOException {

        if (type == BasicFileAttributes.class || type == HadoopFileAttributes.class)
            return (A) toHadoopPath(path).getAttributes();

        if (type == PosixFileAttributes.class)
            return (A) toHadoopPath(path).getPosixAttributes();

        throw new UnsupportedOperationException("readAttributes:" + type.getName());
    }

    @Override
    public Map readAttributes(Path path, String attributes, LinkOption... options) throws IOException {
        return toHadoopPath(path).getFileSystem().readAttributes(toHadoopPath(path), attributes, options);
    }

    @Override
    public void setAttribute(Path path, String attribute, Object value, LinkOption... options) throws IOException {
        toHadoopPath(path).getFileSystem().setAttribute(toHadoopPath(path), attribute, value, options);
    }
}