org.apache.commons.vfs2.FileSystem Maven / Gradle / Ivy
Show all versions of commons-vfs2 Show documentation
/*
* 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;
import java.io.File;
/**
* A file system, made up of a hierarchy of files.
*/
public interface FileSystem {
/**
* Returns the root file of this file system.
*
* @return The root FileObject.
* @throws FileSystemException if an error occurs.
*/
FileObject getRoot() throws FileSystemException;
/**
* Returns the name of the root file of this file system. The root name always contains a path String of "/".
*
* @return the root FileName.
*/
FileName getRootName();
/**
* The root URI passed as a file system option or obtained from the rootName.
*
* @return The root URI.
*/
String getRootURI();
/**
* Determines if this file system has a particular capability.
*
* TODO - Move this to another interface, so that set of capabilities can be queried.
*
* @param capability The capability to check for.
* @return true if this filesystem has the requested capability. Note that not all files in the file system may have
* the capability.
*/
boolean hasCapability(Capability capability);
/**
* Returns the parent layer if this is a layered file system.
*
* @return The parent layer, or null if this is not a layered file system.
* @throws FileSystemException if an error occurs.
*/
FileObject getParentLayer() throws FileSystemException;
/**
* Gets the value of an attribute of the file system.
*
* TODO - change to {@code Map getAttributes()} instead?
* TODO - define the standard attribute names, and define which attrs are guaranteed to be present.
*
* @param attrName The name of the attribute.
* @return The value of the attribute.
* @throws org.apache.commons.vfs2.FileSystemException If the file does not exist, or is being written, or if the
* attribute is unknown.
* @see org.apache.commons.vfs2.FileContent#getAttribute
*/
Object getAttribute(String attrName) throws FileSystemException;
/**
* Sets the value of an attribute of the file's content. Creates the file if it does not exist.
*
* @param attrName The name of the attribute.
* @param value The value of the attribute.
* @throws FileSystemException If the file is read-only, or is being read, or if the attribute is not supported, or
* on error setting the attribute.
* @see FileContent#setAttribute
*/
void setAttribute(String attrName, Object value) throws FileSystemException;
/**
* Finds a file in this file system.
*
* @param name The name of the file.
* @return The file. Never returns null.
* @throws FileSystemException if an error occurs.
*/
FileObject resolveFile(FileName name) throws FileSystemException;
/**
* Finds a file in this file system.
*
* @param name The name of the file. This must be an absolute path.
* @return The file. Never returns null.
* @throws FileSystemException if an error occurs.
*/
FileObject resolveFile(String name) throws FileSystemException;
/**
* Adds a listener on a file in this file system.
*
* @param file The file to attach the listener to.
* @param listener The listener to add.
*/
void addListener(FileObject file, FileListener listener);
/**
* Removes a listener from a file in this file system.
*
* @param file The file to remove the listener from.
* @param listener The listener to remove.
*/
void removeListener(FileObject file, FileListener listener);
/**
* Adds a junction to this file system. A junction is a link that attaches the supplied file to a point in this file
* system, making it look like part of the file system.
*
* @param junctionPoint The point in this file system to add the junction.
* @param targetFile The file to link to.
* @throws FileSystemException If this file system does not support junctions, or the junction point or target file
* is invalid (the file system may not support nested junctions, for example).
*/
void addJunction(String junctionPoint, FileObject targetFile) throws FileSystemException;
/**
* Removes a junction from this file system.
*
* @param junctionPoint The junction to remove.
* @throws FileSystemException On error removing the junction.
*/
void removeJunction(String junctionPoint) throws FileSystemException;
/**
* Creates a temporary local copy of a file and its descendants. If this file is already a local file, a copy is not
* made.
*
* Note that the local copy may include additonal files, that were not selected by the given selector.
*
* TODO - Add options to indicate whether the caller is happy to deal with extra files being present locally (eg if
* the file has been replicated previously), or whether the caller expects only the selected files to be present.
*
* @param file The file to replicate.
* @param selector The selector to use to select the files to replicate.
* @return The local copy of this file.
* @throws FileSystemException If this file does not exist, or on error replicating the file.
*/
File replicateFile(FileObject file, FileSelector selector) throws FileSystemException;
/**
* Returns the FileSystemOptions used to instantiate this filesystem.
*
* @return The FileSystemOptions.
*/
FileSystemOptions getFileSystemOptions();
/**
* Returns a reference to the FileSytemManager.
*
* @return The FileSystemManager.
*/
FileSystemManager getFileSystemManager();
/**
* Returns the accuracy of the last modification time.
*
* The local file provider is not very smart in figuring this out, for remote access to file systems the providers
* typically don't know the value of the underlying real file system.
*
* @return the accuracy of the last modification time in milliseconds. A value of 0 means perfectly accurate,
* anything {@literal > 0} might be off by this value. For example, sftp has an accuracy of 1000 ms.
*/
double getLastModTimeAccuracy();
}