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package de.lmu.ifi.dbs.elki.utilities;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2011
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;
import java.util.zip.GZIPInputStream;
/**
* Various static helper methods to deal with files and file names.
*
* @author Erich Schubert
*/
public final class FileUtil {
/**
* Returns the lower case extension of the selected file.
*
* If no file is selected, <code>null</code> is returned.
*
* @param file File object
* @return Returns the extension of the selected file in lower case or
* <code>null</code>
*/
public static String getFilenameExtension(File file) {
return getFilenameExtension(file.getName());
}
/**
* Returns the lower case extension of the selected file.
*
* If no file is selected, <code>null</code> is returned.
*
* @param name File name
* @return Returns the extension of the selected file in lower case or
* <code>null</code>
*/
public static String getFilenameExtension(String name) {
if(name == null) {
return null;
}
int index = name.lastIndexOf(".");
if(index >= name.length() - 1) {
return null;
}
return name.substring(name.lastIndexOf(".") + 1).toLowerCase();
}
/**
* Try to open a file, first trying the file system,
* then falling back to the classpath.
*
* @param filename File name in system notation
* @return Input stream
* @throws FileNotFoundException When no file was found.
*/
public static InputStream openSystemFile(String filename) throws FileNotFoundException {
try {
return new FileInputStream(filename);
}
catch(FileNotFoundException e) {
// try with classloader
String resname = filename.replace(File.separatorChar, '/');
InputStream result = ClassLoader.getSystemResourceAsStream(resname);
if (result == null) {
throw e;
}
return result;
}
}
/**
* Try to open a stream as gzip, if it starts with the gzip magic.
*
* TODO: move to utils package.
*
* @param in original input stream
* @return old input stream or a {@link GZIPInputStream} if appropriate.
* @throws IOException on IO error
*/
public static InputStream tryGzipInput(InputStream in) throws IOException {
// try autodetecting gzip compression.
if (!in.markSupported()) {
PushbackInputStream pb = new PushbackInputStream(in, 16);
in = pb;
// read a magic from the file header
byte[] magic = {0, 0};
pb.read(magic);
pb.unread(magic);
if (magic[0] == 31 && magic[1] == -117) {
in = new GZIPInputStream(pb);
}
} else
if (in.markSupported()) {
in.mark(16);
if (in.read() == 31 && in.read() == -117) {
in.reset();
in = new GZIPInputStream(in);
} else {
// just rewind the stream
in.reset();
}
}
return in;
}
/**
* Try to locate an file in the filesystem, given a partial name and a prefix.
*
* @param name file name
* @param basedir extra base directory to try
* @return file, if the file could be found. {@code null} otherwise
*/
public static File locateFile(String name, String basedir) {
// Try exact match first.
File f = new File(name);
if(f.exists()) {
return f;
}
// Try with base directory
if(basedir != null) {
f = new File(basedir, name);
// logger.warning("Trying: "+f.getAbsolutePath());
if(f.exists()) {
return f;
}
}
// try stripping whitespace
{
String name2 = name.trim();
if(!name.equals(name2)) {
// logger.warning("Trying without whitespace.");
f = locateFile(name2, basedir);
if(f != null) {
return f;
}
}
}
// try substituting path separators
{
String name2 = name.replace('/',File.separatorChar);
if (!name.equals(name2)) {
// logger.warning("Trying with replaced separators.");
f = locateFile(name2, basedir);
if(f != null) {
return f;
}
}
name2 = name.replace('\\',File.separatorChar);
if (!name.equals(name2)) {
// logger.warning("Trying with replaced separators.");
f = locateFile(name2, basedir);
if(f != null) {
return f;
}
}
}
// try stripping extra characters, such as quotes.
if(name.length() > 2 && name.charAt(0) == '"' && name.charAt(name.length() - 1) == '"') {
// logger.warning("Trying without quotes.");
f = locateFile(name.substring(1, name.length() - 1), basedir);
if(f != null) {
return f;
}
}
return null;
}
}
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