/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.vfs2.provider;
import org.apache.commons.vfs2.FileName;
import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSystem;
import org.apache.commons.vfs2.FileSystemException;
import org.apache.commons.vfs2.FileSystemOptions;
/**
* A {@link FileProvider} that is layered on top of another, such as the
* contents of a zip or tar file.
*
* @author <a href="http://commons.apache.org/vfs/team-list.html">Commons VFS team</a>
* @version $Revision: 1035122 $ $Date: 2010-11-15 08:22:44 +0530 (Mon, 15 Nov 2010) $
*/
public abstract class AbstractLayeredFileProvider
extends AbstractFileProvider
implements FileProvider
{
public AbstractLayeredFileProvider()
{
super();
setFileNameParser(LayeredFileNameParser.getInstance());
}
/**
* Locates a file object, by absolute URI.
* @param baseFile The base FileObject.
* @param uri The name of the file to locate.
* @param properties The FileSystemOptions.
* @return The FileObject if it is located, null otherwise.
* @throws FileSystemException if an error occurs.
*/
public FileObject findFile(final FileObject baseFile,
final String uri,
final FileSystemOptions properties) throws FileSystemException
{
// Split the URI up into its parts
final LayeredFileName name = (LayeredFileName) parseUri(baseFile != null ? baseFile.getName() : null, uri);
// Make the URI canonical
// Resolve the outer file name
final FileName fileName = name.getOuterName();
final FileObject file = getContext().resolveFile(baseFile, fileName.getURI(), properties);
// Create the file system
final FileObject rootFile = createFileSystem(name.getScheme(), file, properties);
// Resolve the file
return rootFile.resolveFile(name.getPath());
}
/**
* Creates a layered file system.
* @param scheme The protocol to use.
* @param file a FileObject.
* @param fileSystemOptions Options to access the FileSystem.
* @return A FileObject associated with the new FileSystem.
* @throws FileSystemException if an error occurs.
*/
@Override
public synchronized FileObject createFileSystem(final String scheme,
final FileObject file,
final FileSystemOptions fileSystemOptions)
throws FileSystemException
{
// Check if cached
final FileName rootName = file.getName();
FileSystem fs = findFileSystem(rootName, null);
if (fs == null)
{
// Create the file system
fs = doCreateFileSystem(scheme, file, fileSystemOptions);
addFileSystem(rootName, fs);
}
return fs.getRoot();
}
/**
* Creates a layered file system. This method is called if the file system
* is not cached. The file system may implement {@link VfsComponent}.
*
* @param scheme The URI scheme.
* @param file The file to create the file system on top of.
* @return The file system.
*/
protected abstract FileSystem doCreateFileSystem(final String scheme,
final FileObject file,
final FileSystemOptions fileSystemOptions)
throws FileSystemException;
}