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Provides common utility functions
/*
* Copyright (c) CQSE GmbH
*
* 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 org.conqat.lib.commons.filesystem;
import java.io.File;
import java.io.FileFilter;
import java.io.FilenameFilter;
import java.io.IOException;
import java.net.URI;
/**
* This class represents files that are guaranteed to be canonical. For this class methods
* getPath(), getAbsolutePath() and getCanonicalPath() all
* return the same (canonical) path.
*
* @author deissenb
*/
public class CanonicalFile extends File {
/** Version used for serialization. */
private static final long serialVersionUID = 1;
/**
* Create new canonical file from existing file.
*/
public CanonicalFile(File file) throws IOException {
super(file.getCanonicalPath());
}
/**
* Create new canonical file.
*
* @see File#File(String)
*/
public CanonicalFile(String pathname) throws IOException {
super(new File(pathname).getCanonicalPath());
}
/**
* Create new canonical file.
*
* @see File#File(File, String)
*/
public CanonicalFile(File parent, String child) throws IOException {
this(new File(parent, child));
}
/**
* Create new canonical file.
*
* @see File#File(String, String)
*/
public CanonicalFile(String parent, String child) throws IOException {
this(new File(parent, child));
}
/**
* Create new canonical file.
*
* @see File#File(URI)
*/
public CanonicalFile(URI uri) throws IOException {
super(new File(uri).getCanonicalPath());
}
/**
* Returns the canonical file itself. Use {@link #getCanonicalFile()} for consistency reasons.
*/
@Deprecated
@Override
public CanonicalFile getAbsoluteFile() {
return this;
}
/** Returns the canonical file itself. */
@Override
public CanonicalFile getCanonicalFile() {
return this;
}
/**
* Same as {@link File#listFiles()} but returns canonical files. If for some strange reason the
* files below a canonical file cannot be canonized, this may throw an {@link AssertionError}.
*
* If this abstract pathname does not denote a directory, then this method returns {@code null}.
*/
@Override
public CanonicalFile[] listFiles() {
File[] files = super.listFiles();
if (files == null) {
return null;
}
return canonize(files);
}
/**
* Same as {@link File#listFiles(FileFilter)} but returns canonical files. If for some strange
* reason the files below a canonical file cannot be canonized, this may throw an
* {@link AssertionError}.
*
* If this abstract pathname does not denote a directory, then this method returns {@code null}.
*/
@Override
public CanonicalFile[] listFiles(FileFilter filter) {
File[] files = super.listFiles(filter);
if (files == null) {
return null;
}
CanonicalFile[] result = new CanonicalFile[files.length];
for (int i = 0; i < result.length; i++) {
result[i] = canonize(files[i].getAbsoluteFile());
}
return result;
}
/**
* Same as {@link File#listFiles(FilenameFilter)} but returns canonical files. If for some strange
* reason the files below a canonical file cannot be canonized, this may throw an
* {@link AssertionError}.
*
* If this abstract pathname does not denote a directory, then this method returns {@code null}.
*/
@Override
public CanonicalFile[] listFiles(FilenameFilter filter) {
File[] files = super.listFiles(filter);
if (files == null) {
return null;
}
return canonize(files);
}
/**
* Same as {@link File#getParentFile()} but returns a canonical file. If for some strange reason the
* parent file of a canonical file cannot be canonized, this may throw an {@link AssertionError}.
*/
@Override
public CanonicalFile getParentFile() {
File parent = super.getParentFile();
if (parent == null) {
return null;
}
return canonize(parent);
}
/** Checks if this file is a file an can be read. */
public boolean isReadableFile() {
return isFile() && canRead();
}
/**
* This method is overridden to save effort for call to {@link File#getCanonicalPath()}.
*/
@Override
public String getCanonicalPath() {
return super.getPath();
}
/**
* This method is overridden to save effort for call to {@link File#getAbsolutePath()}. Use
* {@link #getCanonicalPath()} for consistency reasons.
*/
@Deprecated
@Override
public String getAbsolutePath() {
return super.getPath();
}
/**
* Use {@link #getCanonicalPath()} for consistency reasons.
*/
@Deprecated
@Override
public String getPath() {
return super.getPath();
}
/**
* Returns the extension of the file.
*
* @return File extension, i.e. "java" for "FileSystemUtils.java", or null, if the file
* has no extension (i.e. if a filename contains no '.'), returns the empty string if the
* '.' is the filename's last character.
*/
public String getExtension() {
return FileSystemUtils.getFileExtension(this);
}
/**
* Canonizes list of filenames. If a file could not be canonized, this throws an
* {@link AssertionError}.
*/
private static CanonicalFile[] canonize(File[] files) {
CanonicalFile[] result = new CanonicalFile[files.length];
for (int i = 0; i < result.length; i++) {
result[i] = canonize(files[i]);
}
return result;
}
/**
* Canonizes filename. If a file could not be canonized, this throws an {@link AssertionError}.
*/
private static CanonicalFile canonize(File file) {
try {
return new CanonicalFile(file);
} catch (IOException e) {
throw new AssertionError("Problems creating canonical path for " + file + ": " + e.getMessage());
}
}
}