Java tutorial
/*********************************************************************************************************************** * * Copyright (C) 2010 by the Stratosphere project (http://stratosphere.eu) * * 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. * **********************************************************************************************************************/ /** * This file is based on source code from the Hadoop Project (http://hadoop.apache.org/), licensed by the Apache * Software Foundation (ASF) under the Apache License, Version 2.0. See the NOTICE file distributed with this work for * additional information regarding copyright ownership. */ package eu.stratosphere.nephele.fs.file; import java.io.File; import java.io.FileNotFoundException; import java.io.IOException; import java.net.InetAddress; import java.net.URI; import java.net.UnknownHostException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import eu.stratosphere.nephele.fs.BlockLocation; import eu.stratosphere.nephele.fs.FSDataInputStream; import eu.stratosphere.nephele.fs.FSDataOutputStream; import eu.stratosphere.nephele.fs.FileStatus; import eu.stratosphere.nephele.fs.FileSystem; import eu.stratosphere.nephele.fs.Path; /** * The class <code>LocalFile</code> provides an implementation of the {@link FileSystem} interface for the local file * system. * * @author warneke */ public class LocalFileSystem extends FileSystem { /** * Path pointing to the current working directory. */ private Path workingDir = null; /** * The URI representing the local file system. */ private final URI name = URI.create("file:///"); /** * The host name of this machine; */ private final String hostName; private static final Log LOG = LogFactory.getLog(LocalFileSystem.class); /** * Constructs a new <code>LocalFileSystem</code> object. */ public LocalFileSystem() { this.workingDir = new Path(System.getProperty("user.dir")).makeQualified(this); String tmp = "unknownHost"; try { tmp = InetAddress.getLocalHost().getHostName(); } catch (UnknownHostException e) { LOG.error(e); } this.hostName = tmp; } /** * {@inheritDoc} */ @Override public BlockLocation[] getFileBlockLocations(final FileStatus file, final long start, final long len) throws IOException { final BlockLocation[] blockLocations = new BlockLocation[1]; blockLocations[0] = new LocalBlockLocation(this.hostName, file.getLen()); return blockLocations; } /** * {@inheritDoc} */ @Override public FileStatus getFileStatus(Path f) throws IOException { final File path = pathToFile(f); if (path.exists()) { return new LocalFileStatus(pathToFile(f), this); } else { throw new FileNotFoundException("File " + f + " does not exist."); } } /** * {@inheritDoc} */ @Override public URI getUri() { return name; } /** * {@inheritDoc} */ @Override public Path getWorkingDirectory() { return workingDir; } /** * {@inheritDoc} */ @Override public void initialize(final URI name) throws IOException { // TODO Auto-generated method stub } /** * {@inheritDoc} */ @Override public FSDataInputStream open(final Path f, final int bufferSize) throws IOException { return open(f); } /** * {@inheritDoc} */ @Override public FSDataInputStream open(final Path f) throws IOException { final File file = pathToFile(f); return new LocalDataInputStream(file); } /** * {@inheritDoc} */ private File pathToFile(Path path) { if (!path.isAbsolute()) { path = new Path(getWorkingDirectory(), path); } return new File(path.toUri().getPath()); } /** * {@inheritDoc} */ @Override public FileStatus[] listStatus(final Path f) throws IOException { final File localf = pathToFile(f); FileStatus[] results; if (!localf.exists()) { return null; } if (localf.isFile()) { return new FileStatus[] { new LocalFileStatus(localf, this) }; } final String[] names = localf.list(); if (names == null) { return null; } results = new FileStatus[names.length]; for (int i = 0; i < names.length; i++) { results[i] = getFileStatus(new Path(f, names[i])); } return results; } /** * {@inheritDoc} */ @Override public boolean delete(final Path f, final boolean recursive) throws IOException { final File file = pathToFile(f); if (file.isFile()) { return file.delete(); } else if ((!recursive) && file.isDirectory() && (file.listFiles().length != 0)) { throw new IOException("Directory " + file.toString() + " is not empty"); } return delete(file); } /** * Deletes the given file or directory. * * @param f * the file to be deleted * @return <code>true</code> if all files were deleted successfully, <code>false</code> otherwise * @throws IOException * thrown if an error occurred while deleting the files/directories */ private boolean delete(final File f) throws IOException { if (f.isDirectory()) { final File[] files = f.listFiles(); for (int i = 0; i < files.length; i++) { final boolean del = delete(files[i]); if (del == false) { return false; } } } else { return f.delete(); } // Now directory is empty return f.delete(); } /** * Recursively creates the directory specified by the provided path. * * @return <code>true</code>if the directories either already existed or have been created successfully, * <code>false</code> otherwise * @throws IOException * thrown if an error occurred while creating the directory/directories */ public boolean mkdirs(final Path f) throws IOException { final Path parent = f.getParent(); final File p2f = pathToFile(f); return (parent == null || mkdirs(parent)) && (p2f.mkdir() || p2f.isDirectory()); } /** * {@inheritDoc} */ @Override public FSDataOutputStream create(final Path f, final boolean overwrite, final int bufferSize, final short replication, final long blockSize) throws IOException { if (exists(f) && !overwrite) { throw new IOException("File already exists:" + f); } final Path parent = f.getParent(); if (parent != null && !mkdirs(parent)) { throw new IOException("Mkdirs failed to create " + parent.toString()); } final File file = pathToFile(f); return new LocalDataOutputStream(file); } /** * {@inheritDoc} */ @Override public FSDataOutputStream create(final Path f, final boolean overwrite) throws IOException { return create(f, overwrite, 0, (short) 0, 0); } /** * {@inheritDoc} */ @Override public boolean rename(final Path src, final Path dst) throws IOException { final File srcFile = pathToFile(src); final File dstFile = pathToFile(dst); return srcFile.renameTo(dstFile); } }