/* * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.nio.file; import java.nio.file.attribute.*;import java.io.IOException; /** * Storage for files. A {@code FileStore} represents a storage pool, device, * partition, volume, concrete file system or other implementation specific means * of file storage. The {@code FileStore} for where a file is stored is obtained * by invoking the {@link Files#getFileStore getFileStore} method, or all file * stores can be enumerated by invoking the {@link FileSystem#getFileStores * getFileStores} method. * * <p> In addition to the methods defined by this class, a file store may support * one or more {@link FileStoreAttributeView FileStoreAttributeView} classes * that provide a read-only or updatable view of a set of file store attributes. * * @since 1.7 */ public abstract class FileStore {     /**     * Initializes a new instance of this class.     */    protected FileStore() {    }     /**     * Returns the name of this file store. The format of the name is highly     * implementation specific. It will typically be the name of the storage     * pool or volume.     *     * <p> The string returned by this method may differ from the string     * returned by the {@link Object#toString() toString} method.     *     * @return  the name of this file store     */    public abstract String name();     /**     * Returns the <em>type</em> of this file store. The format of the string     * returned by this method is highly implementation specific. It may     * indicate, for example, the format used or if the file store is local     * or remote.     *     * @return  a string representing the type of this file store     */    public abstract String type();     /**     * Tells whether this file store is read-only. A file store is read-only if     * it does not support write operations or other changes to files. Any     * attempt to create a file, open an existing file for writing etc. causes     * an {@code IOException} to be thrown.     *     * @return  {@code true} if, and only if, this file store is read-only     */    public abstract boolean isReadOnly();     /**     * Returns the size, in bytes, of the file store.     *     * @return  the size of the file store, in bytes     *     * @throws  IOException     *          if an I/O error occurs     */    public abstract long getTotalSpace() throws IOException;     /**     * Returns the number of bytes available to this Java virtual machine on the     * file store.     *     * <p> The returned number of available bytes is a hint, but not a     * guarantee, that it is possible to use most or any of these bytes.  The     * number of usable bytes is most likely to be accurate immediately     * after the space attributes are obtained. It is likely to be made inaccurate     * by any external I/O operations including those made on the system outside     * of this Java virtual machine.     *     * @return  the number of bytes available     *     * @throws  IOException     *          if an I/O error occurs     */    public abstract long getUsableSpace() throws IOException;     /**     * Returns the number of unallocated bytes in the file store.     *     * <p> The returned number of unallocated bytes is a hint, but not a     * guarantee, that it is possible to use most or any of these bytes.  The     * number of unallocated bytes is most likely to be accurate immediately     * after the space attributes are obtained. It is likely to be     * made inaccurate by any external I/O operations including those made on     * the system outside of this virtual machine.     *     * @return  the number of unallocated bytes     *     * @throws  IOException     *          if an I/O error occurs     */    public abstract long getUnallocatedSpace() throws IOException;     /**     * Tells whether or not this file store supports the file attributes     * identified by the given file attribute view.     *     * <p> Invoking this method to test if the file store supports {@link     * BasicFileAttributeView} will always return {@code true}. In the case of     * the default provider, this method cannot guarantee to give the correct     * result when the file store is not a local storage device. The reasons for     * this are implementation specific and therefore unspecified.     *     * @param   type     *          the file attribute view type     *     * @return  {@code true} if, and only if, the file attribute view is     *          supported     */    public abstract boolean supportsFileAttributeView(Class<? extends FileAttributeView> type);     /**     * Tells whether or not this file store supports the file attributes     * identified by the given file attribute view.     *     * <p> Invoking this method to test if the file store supports {@link     * BasicFileAttributeView}, identified by the name "{@code basic}" will     * always return {@code true}. In the case of the default provider, this     * method cannot guarantee to give the correct result when the file store is     * not a local storage device. The reasons for this are implementation     * specific and therefore unspecified.     *     * @param   name     *          the {@link FileAttributeView#name name} of file attribute view     *     * @return  {@code true} if, and only if, the file attribute view is     *          supported     */    public abstract boolean supportsFileAttributeView(String name);     /**     * Returns a {@code FileStoreAttributeView} of the given type.     *     * <p> This method is intended to be used where the file store attribute     * view defines type-safe methods to read or update the file store attributes.     * The {@code type} parameter is the type of the attribute view required and     * the method returns an instance of that type if supported.     *     * @param   type     *          the {@code Class} object corresponding to the attribute view     *     * @return  a file store attribute view of the specified type or     *          {@code null} if the attribute view is not available     */    public abstract <V extends FileStoreAttributeView> V        getFileStoreAttributeView(Class<V> type);     /**     * Reads the value of a file store attribute.     *     * <p> The {@code attribute} parameter identifies the attribute to be read     * and takes the form:     * <blockquote>     * <i>view-name</i><b>:</b><i>attribute-name</i>     * </blockquote>     * where the character {@code ':'} stands for itself.     *     * <p> <i>view-name</i> is the {@link FileStoreAttributeView#name name} of     * a {@link FileStore AttributeView} that identifies a set of file attributes.     * <i>attribute-name</i> is the name of the attribute.     *     * <p> <b>Usage Example:</b>     * Suppose we want to know if ZFS compression is enabled (assuming the "zfs"     * view is supported):     * <pre>     *    boolean compression = (Boolean)fs.getAttribute("zfs:compression");     * </pre>     *     * @param   attribute     *          the attribute to read      * @return  the attribute value; {@code null} may be a valid valid for some     *          attributes     *     * @throws  UnsupportedOperationException     *          if the attribute view is not available or it does not support     *          reading the attribute     * @throws  IOException     *          if an I/O error occurs     */    public abstract Object getAttribute(String attribute) throws IOException;}