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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package org.apache.commons.vfs;
    18
    19  import java.io.File;
    20
    21  /***
    22   * A file system, made up of a hierarchy of files.
    23   *
    24   * @author <a href="mailto:adammurdoch@apache.org">Adam Murdoch</a>
    25   * @version $Revision: 484648 $ $Date: 2006-12-08 17:18:36 +0100 (Fr, 08 Dez 2006) $
    26   */
    27  public interface FileSystem
    28  {
    29      /***
    30       * Returns the root file of this file system.
    31       */
    32      FileObject getRoot() throws FileSystemException;
    33
    34      /***
    35       * Returns the name of the root file of this file system.
    36       */
    37      FileName getRootName();
    38
    39      /***
    40       * Determines if this file system has a particular capability.
    41       *
    42       * @param capability The capability to check for.
    43       * @return true if this filesystem has the requested capability.
    44       *         Note that not all files in the file system may have the
    45       *         capability.
    46       * @todo Move this to another interface, so that set of capabilities can be queried.
    47       */
    48      boolean hasCapability(Capability capability);
    49
    50      /***
    51       * Returns the parent layer if this is a layered file system.
    52       *
    53       * @return The parent layer, or null if this is not a layered file system.
    54       */
    55      FileObject getParentLayer() throws FileSystemException;
    56
    57      /***
    58       * Gets the value of an attribute of the file system.
    59       * <p/>
    60       * <p>TODO - change to <code>Map getAttributes()</code> instead?
    61       * <p/>
    62       * <p>TODO - define the standard attribute names, and define which attrs
    63       * are guaranteed to be present.
    64       *
    65       * @param attrName The name of the attribute.
    66       * @return The value of the attribute.
    67       * @throws org.apache.commons.vfs.FileSystemException
    68       *          If the file does not exist, or is being written, or if the
    69       *          attribute is unknown.
    70       * @see org.apache.commons.vfs.FileContent#getAttribute
    71       */
    72      Object getAttribute(String attrName) throws FileSystemException;
    73
    74      /***
    75       * Sets the value of an attribute of the file's content.  Creates the
    76       * file if it does not exist.
    77       *
    78       * @param attrName The name of the attribute.
    79       * @param value    The value of the attribute.
    80       * @throws FileSystemException If the file is read-only, or is being read, or if the attribute
    81       *                             is not supported, or on error setting the attribute.
    82       * @see FileContent#setAttribute
    83       */
    84      void setAttribute(String attrName, Object value)
    85          throws FileSystemException;
    86
    87      /***
    88       * Finds a file in this file system.
    89       *
    90       * @param name The name of the file.
    91       * @return The file.  Never returns null.
    92       */
    93      FileObject resolveFile(FileName name) throws FileSystemException;
    94
    95      /***
    96       * Finds a file in this file system.
    97       *
    98       * @param name The name of the file.  This must be an absolute path.
    99       * @return The file.  Never returns null.
    100      */
    101     FileObject resolveFile(String name) throws FileSystemException;
    102
    103     /***
    104      * Adds a listener on a file in this file system.
    105      *
    106      * @param file     The file to attach the listener to.
    107      * @param listener The listener to add.
    108      */
    109     void addListener(FileObject file, FileListener listener);
    110
    111     /***
    112      * Removes a listener from a file in this file system.
    113      *
    114      * @param file     The file to remove the listener from.
    115      * @param listener The listener to remove.
    116      */
    117     void removeListener(FileObject file, FileListener listener);
    118
    119     /***
    120      * Adds a junction to this file system.  A junction is a link that attaches
    121      * the supplied file to a point in this file system, making it look like
    122      * part of the file system.
    123      *
    124      * @param junctionPoint The point in this file system to add the junction.
    125      * @param targetFile    The file to link to.
    126      * @throws FileSystemException If this file system does not support junctions, or the junction
    127      *                             point or target file is invalid (the file system may not support
    128      *                             nested junctions, for example).
    129      */
    130     void addJunction(String junctionPoint, FileObject targetFile)
    131         throws FileSystemException;
    132
    133     /***
    134      * Removes a junction from this file system.
    135      *
    136      * @param junctionPoint The junction to remove.
    137      * @throws FileSystemException On error removing the junction.
    138      */
    139     void removeJunction(String junctionPoint) throws FileSystemException;
    140
    141     /***
    142      * Creates a temporary local copy of a file and its descendents.  If
    143      * this file is already a local file, a copy is not made.
    144      * <p/>
    145      * <p>Note that the local copy may include additonal files, that were
    146      * not selected by the given selector.
    147      *
    148      * @param file     The file to replicate.
    149      * @param selector The selector to use to select the files to replicate.
    150      * @return The local copy of this file.
    151      * @throws FileSystemException If this file does not exist, or on error replicating the file.
    152      * @todo Add options to indicate whether the caller is happy to deal with
    153      * extra files being present locally (eg if the file has been
    154      * replicated previously), or whether the caller expects only
    155      * the selected files to be present.
    156      */
    157     File replicateFile(FileObject file, FileSelector selector)
    158         throws FileSystemException;
    159
    160     /***
    161      * Returns the FileSystemOptions used to instantiate this filesystem
    162      */
    163     FileSystemOptions getFileSystemOptions();
    164
    165     /***
    166      * Returns a reference to the FileSytemManager
    167      */
    168     FileSystemManager getFileSystemManager();
    169
    170     /***
    171      * Returns the accuracy of the last modification time
    172      *
    173      * @return ms 0 perfectly accurate, >0 might be off by this value e.g. sftp 1000ms
    174      */
    175     double getLastModTimeAccuracy();
    176 }