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 * 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
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 *      http://www.apache.org/licenses/LICENSE-2.0
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 * distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.commons.vfs2.impl;

import java.util.Collection;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.vfs2.Capability;
import org.apache.commons.vfs2.FileName;
import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSystemException;
import org.apache.commons.vfs2.FileSystemOptions;
import org.apache.commons.vfs2.FileType;
import org.apache.commons.vfs2.NameScope;
import org.apache.commons.vfs2.provider.AbstractFileName;
import org.apache.commons.vfs2.provider.AbstractFileSystem;
import org.apache.commons.vfs2.provider.DelegateFileObject;

A logical file system, made up of set of junctions, or links, to files from other file systems.

TODO - Handle nested junctions.

/** * A logical file system, made up of set of junctions, or links, to files from other file systems. * <p> * TODO - Handle nested junctions. * </p> */
public class VirtualFileSystem extends AbstractFileSystem { private final Map<FileName, FileObject> junctions = new HashMap<>(); public VirtualFileSystem(final AbstractFileName rootName, final FileSystemOptions fileSystemOptions) { super(rootName, null, fileSystemOptions); }
Adds the capabilities of this file system.
/** * Adds the capabilities of this file system. */
@Override protected void addCapabilities(final Collection<Capability> caps) { // TODO - this isn't really true caps.add(Capability.ATTRIBUTES); caps.add(Capability.CREATE); caps.add(Capability.DELETE); caps.add(Capability.GET_TYPE); caps.add(Capability.JUNCTIONS); caps.add(Capability.GET_LAST_MODIFIED); caps.add(Capability.SET_LAST_MODIFIED_FILE); caps.add(Capability.SET_LAST_MODIFIED_FOLDER); caps.add(Capability.LIST_CHILDREN); caps.add(Capability.READ_CONTENT); caps.add(Capability.SIGNING); caps.add(Capability.WRITE_CONTENT); caps.add(Capability.APPEND_CONTENT); }
Creates a file object. This method is called only if the requested file is not cached.
/** * Creates a file object. This method is called only if the requested file is not cached. */
@Override protected FileObject createFile(final AbstractFileName name) throws Exception { // Find the file that the name points to final FileName junctionPoint = getJunctionForFile(name); final FileObject file; if (junctionPoint != null) { // Resolve the real file final FileObject junctionFile = junctions.get(junctionPoint); final String relName = junctionPoint.getRelativeName(name); file = junctionFile.resolveFile(relName, NameScope.DESCENDENT_OR_SELF); } else { file = null; } // Return a wrapper around the file return new DelegateFileObject(name, this, file); }
Adds a junction to this file system.
Params:
  • junctionPoint – The location of the junction.
  • targetFile – The target file to base the junction on.
Throws:
/** * Adds a junction to this file system. * * @param junctionPoint The location of the junction. * @param targetFile The target file to base the junction on. * @throws FileSystemException if an error occurs. */
@Override public void addJunction(final String junctionPoint, final FileObject targetFile) throws FileSystemException { final FileName junctionName = getFileSystemManager().resolveName(getRootName(), junctionPoint); // Check for nested junction - these are not supported yet if (getJunctionForFile(junctionName) != null) { throw new FileSystemException("vfs.impl/nested-junction.error", junctionName); } try { // Add to junction table junctions.put(junctionName, targetFile); // Attach to file final DelegateFileObject junctionFile = (DelegateFileObject) getFileFromCache(junctionName); if (junctionFile != null) { junctionFile.setFile(targetFile); } // Create ancestors of junction point FileName childName = junctionName; boolean done = false; for (AbstractFileName parentName = (AbstractFileName) childName.getParent(); !done && parentName != null; childName = parentName, parentName = (AbstractFileName) parentName .getParent()) { DelegateFileObject file = (DelegateFileObject) getFileFromCache(parentName); if (file == null) { file = new DelegateFileObject(parentName, this, null); putFileToCache(file); } else { done = file.exists(); } // As this is the parent of our junction it has to be a folder file.attachChild(childName, FileType.FOLDER); } // TODO - attach all cached children of the junction point to their real file } catch (final Exception e) { throw new FileSystemException("vfs.impl/create-junction.error", junctionName, e); } }
Removes a junction from this file system.
Params:
  • junctionPoint – The junction to remove.
Throws:
/** * Removes a junction from this file system. * * @param junctionPoint The junction to remove. * @throws FileSystemException if an error occurs. */
@Override public void removeJunction(final String junctionPoint) throws FileSystemException { final FileName junctionName = getFileSystemManager().resolveName(getRootName(), junctionPoint); junctions.remove(junctionName); // TODO - remove from parents of junction point // TODO - detach all cached children of the junction point from their real file }
Locates the junction point for the junction containing the given file.
Params:
  • name – The FileName.
Returns:the FileName where the junction occurs.
/** * Locates the junction point for the junction containing the given file. * * @param name The FileName. * @return the FileName where the junction occurs. */
private FileName getJunctionForFile(final FileName name) { if (junctions.containsKey(name)) { // The name points to the junction point directly return name; } // Find matching junction for (final FileName junctionPoint : junctions.keySet()) { if (junctionPoint.isDescendent(name)) { return junctionPoint; } } // None return null; } @Override public void close() { super.close(); junctions.clear(); } }