/*
* Copyright 2002-2005 The Apache Software Foundation.
*
* 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.apache.commons.vfs.provider;
import org.apache.commons.vfs.FileName;
import org.apache.commons.vfs.FileObject;
import org.apache.commons.vfs.FileSystem;
import org.apache.commons.vfs.FileSystemException;
import org.apache.commons.vfs.FileSystemOptions;
/**
* A {@link FileProvider} that is layered on top of another, such as the
* contents of a zip or tar file.
*
* @author <a href="mailto:adammurdoch@apache.org">Adam Murdoch</a>
*/
public abstract class AbstractLayeredFileProvider
extends AbstractFileProvider
implements FileProvider
{
public AbstractLayeredFileProvider()
{
super();
setFileNameParser(LayeredFileNameParser.getInstance());
}
/**
* Locates a file object, by absolute URI.
*/
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.
*/
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;
}