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      1 /*
      2  * Copyright (C) 2003-2009 JNode.org
      3  *               2009,2010 Matthias Treydte <mt (at) waldheinz.de>
      4  *
      5  * This library is free software; you can redistribute it and/or modify it
      6  * under the terms of the GNU Lesser General Public License as published
      7  * by the Free Software Foundation; either version 2.1 of the License, or
      8  * (at your option) any later version.
      9  *
     10  * This library is distributed in the hope that it will be useful, but
     11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
     12  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
     13  * License for more details.
     14  *
     15  * You should have received a copy of the GNU Lesser General Public License
     16  * along with this library; If not, write to the Free Software Foundation, Inc.,
     17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
     18  */
     19 
     20 package de.waldheinz.fs;
     21 
     22 import java.io.IOException;
     23 
     24 /**
     25  * Abstract class with common things in different FileSystem implementations.
     26  *
     27  * @author Fabien DUMINY
     28  * @author Matthias Treydte &lt;waldheinz at gmail.com&gt;
     29  */
     30 public abstract class AbstractFileSystem implements FileSystem {
     31     private final boolean readOnly;
     32     private boolean closed;
     33 
     34     /**
     35      * Creates a new {@code AbstractFileSystem}.
     36      *
     37      * @param readOnly if the file system should be read-only
     38      */
     39     public AbstractFileSystem(boolean readOnly) {
     40         this.closed = false;
     41         this.readOnly = readOnly;
     42     }
     43 
     44     @Override
     45     public void close() throws IOException {
     46         if (!isClosed()) {
     47             if (!isReadOnly()) {
     48                 flush();
     49             }
     50 
     51             closed = true;
     52         }
     53     }
     54 
     55     @Override
     56     public final boolean isClosed() {
     57         return closed;
     58     }
     59 
     60     @Override
     61     public final boolean isReadOnly() {
     62         return readOnly;
     63     }
     64 
     65     /**
     66      * Checks if this {@code FileSystem} was already closed, and throws an
     67      * exception if it was.
     68      *
     69      * @throws IllegalStateException if this {@code FileSystem} was
     70      *      already closed
     71      * @see #isClosed()
     72      * @see #close()
     73      */
     74     protected final void checkClosed() throws IllegalStateException {
     75         if (isClosed()) {
     76             throw new IllegalStateException("file system was already closed");
     77         }
     78     }
     79 
     80     /**
     81      * Checks if this {@code FileSystem} is read-only, and throws an
     82      * exception if it is.
     83      *
     84      * @throws ReadOnlyException if this {@code FileSystem} is read-only
     85      * @see #isReadOnly()
     86      */
     87     protected final void checkReadOnly() throws ReadOnlyException {
     88         if (isReadOnly()) {
     89             throw new ReadOnlyException();
     90         }
     91     }
     92 }
     93