| /* |
| * Copyright (c) 2007, 2009, 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.spi; |
| |
| import java.nio.file.*; |
| import java.nio.file.attribute.FileAttribute; |
| import java.nio.channels.*; |
| import java.net.URI; |
| import java.util.*; |
| import java.util.concurrent.ExecutorService; |
| import java.security.AccessController; |
| import java.security.PrivilegedAction; |
| import java.io.IOException; |
| |
| /** |
| * Service-provider class for file systems. |
| * |
| * <p> A file system provider is a concrete implementation of this class that |
| * implements the abstract methods defined by this class. A provider is |
| * identified by a {@code URI} {@link #getScheme() scheme}. The default provider |
| * is identified by the URI scheme "file". It creates the {@link FileSystem} that |
| * provides access to the file systems accessible to the Java virtual machine. |
| * The {@link FileSystems} class defines how file system providers are located |
| * and loaded. The default provider is typically a system-default provider but |
| * may be overridden if the system property {@code |
| * java.nio.file.spi.DefaultFileSystemProvider} is set. In that case, the |
| * provider has a one argument constructor whose formal parameter type is {@code |
| * FileSystemProvider}. All other providers have a zero argument constructor |
| * that initializes the provider. |
| * |
| * <p> A provider is a factory for one or more {@link FileSystem} instances. Each |
| * file system is identified by a {@code URI} where the URI's scheme matches |
| * the provider's {@link #getScheme scheme}. The default file system, for example, |
| * is identified by the URI {@code "file:///"}. A memory-based file system, |
| * for example, may be identified by a URI such as {@code "memory:///?name=logfs"}. |
| * The {@link #newFileSystem newFileSystem} method may be used to create a file |
| * system, and the {@link #getFileSystem getFileSystem} method may be used to |
| * obtain a reference to an existing file system created by the provider. Where |
| * a provider is the factory for a single file system then it is provider dependent |
| * if the file system is created when the provider is initialized, or later when |
| * the {@code newFileSystem} method is invoked. In the case of the default |
| * provider, the {@code FileSystem} is created when the provider is initialized. |
| * |
| * <p> In addition to file systems, a provider is also a factory for {@link |
| * FileChannel} and {@link AsynchronousFileChannel} channels. The {@link |
| * #newFileChannel newFileChannel} and {@link #newAsynchronousFileChannel |
| * AsynchronousFileChannel} methods are defined to open or create files, returning |
| * a channel to access the file. These methods are invoked by static factory |
| * methods defined in the {@link java.nio.channels} package. |
| * |
| * <p> All of the methods in this class are safe for use by multiple concurrent |
| * threads. |
| * |
| * @since 1.7 |
| */ |
| |
| public abstract class FileSystemProvider { |
| // lock using when loading providers |
| private static final Object lock = new Object(); |
| |
| // installed providers |
| private static volatile List<FileSystemProvider> installedProviders; |
| |
| // used to avoid recursive loading of instaled providers |
| private static boolean loadingProviders = false; |
| |
| private static Void checkPermission() { |
| SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) |
| sm.checkPermission(new RuntimePermission("fileSystemProvider")); |
| return null; |
| } |
| private FileSystemProvider(Void ignore) { } |
| |
| /** |
| * Initializes a new instance of this class. |
| * |
| * <p> During construction a provider may safely access files associated |
| * with the default provider but care needs to be taken to avoid circular |
| * loading of other installed providers. If circular loading of installed |
| * providers is detected then an unspecified error is thrown. |
| * |
| * @throws SecurityException |
| * If a security manager has been installed and it denies |
| * {@link RuntimePermission}<tt>("fileSystemProvider")</tt> |
| */ |
| protected FileSystemProvider() { |
| this(checkPermission()); |
| } |
| |
| // loads all installed providers |
| private static List<FileSystemProvider> loadInstalledProviders() { |
| List<FileSystemProvider> list = new ArrayList<FileSystemProvider>(); |
| |
| ServiceLoader<FileSystemProvider> sl = ServiceLoader |
| .load(FileSystemProvider.class, ClassLoader.getSystemClassLoader()); |
| |
| // ServiceConfigurationError may be throw here |
| for (FileSystemProvider provider: sl) { |
| String scheme = provider.getScheme(); |
| |
| // add to list if the provider is not "file" and isn't a duplicate |
| if (!scheme.equalsIgnoreCase("file")) { |
| boolean found = false; |
| for (FileSystemProvider p: list) { |
| if (p.getScheme().equalsIgnoreCase(scheme)) { |
| found = true; |
| break; |
| } |
| } |
| if (!found) { |
| list.add(provider); |
| } |
| } |
| } |
| return list; |
| } |
| |
| /** |
| * Returns a list of the installed file system providers. |
| * |
| * <p> The first invocation of this method causes the default provider to be |
| * initialized (if not already initialized) and loads any other installed |
| * providers as described by the {@link FileSystems} class. |
| * |
| * @return An unmodifiable list of the installed file system providers. The |
| * list contains at least one element, that is the default file |
| * system provider |
| * |
| * @throws ServiceConfigurationError |
| * When an error occurs while loading a service provider |
| */ |
| public static List<FileSystemProvider> installedProviders() { |
| if (installedProviders == null) { |
| // ensure default provider is initialized |
| FileSystemProvider defaultProvider = FileSystems.getDefault().provider(); |
| |
| synchronized (lock) { |
| if (installedProviders == null) { |
| if (loadingProviders) { |
| throw new Error("Circular loading of installed providers detected"); |
| } |
| loadingProviders = true; |
| |
| List<FileSystemProvider> list = AccessController |
| .doPrivileged(new PrivilegedAction<List<FileSystemProvider>>() { |
| @Override |
| public List<FileSystemProvider> run() { |
| return loadInstalledProviders(); |
| }}); |
| |
| // insert the default provider at the start of the list |
| list.add(0, defaultProvider); |
| |
| installedProviders = Collections.unmodifiableList(list); |
| } |
| } |
| } |
| return installedProviders; |
| } |
| |
| /** |
| * Returns the URI scheme that identifies this provider. |
| * |
| * @return The URI scheme |
| */ |
| public abstract String getScheme(); |
| |
| /** |
| * Constructs a new {@code FileSystem} object identified by a URI. This |
| * method is invoked by the {@link FileSystems#newFileSystem(URI,Map)} |
| * method to open a new file system identified by a URI. |
| * |
| * <p> The {@code uri} parameter is an absolute, hierarchical URI, with a |
| * scheme equal (without regard to case) to the scheme supported by this |
| * provider. The exact form of the URI is highly provider dependent. The |
| * {@code env} parameter is a map of provider specific properties to configure |
| * the file system. |
| * |
| * <p> This method throws {@link FileSystemAlreadyExistsException} if the |
| * file system already exists because it was previously created by an |
| * invocation of this method. Once a file system is {@link FileSystem#close |
| * closed} it is provider-dependent if the provider allows a new file system |
| * to be created with the same URI as a file system it previously created. |
| * |
| * @param uri |
| * URI reference |
| * @param env |
| * A map of provider specific properties to configure the file system; |
| * may be empty |
| * |
| * @return A new file system |
| * |
| * @throws IllegalArgumentException |
| * If the pre-conditions for the {@code uri} parameter aren't met, |
| * or the {@code env} parameter does not contain properties required |
| * by the provider, or a property value is invalid |
| * @throws IOException |
| * An I/O error occurs creating the file system |
| * @throws SecurityException |
| * If a security manager is installed and it denies an unspecified |
| * permission required by the file system provider implementation |
| * @throws FileSystemAlreadyExistsException |
| * If the file system has already been created |
| */ |
| public abstract FileSystem newFileSystem(URI uri, Map<String,?> env) |
| throws IOException; |
| |
| /** |
| * Returns an existing {@code FileSystem} created by this provider. |
| * |
| * <p> This method returns a reference to a {@code FileSystem} that was |
| * created by invoking the {@link #newFileSystem(URI,Map) newFileSystem(URI,Map)} |
| * method. File systems created the {@link #newFileSystem(FileRef,Map) |
| * newFileSystem(FileRef,Map)} method are not returned by this method. |
| * The file system is identified by its {@code URI}. Its exact form |
| * is highly provider dependent. In the case of the default provider the URI's |
| * path component is {@code "/"} and the authority, query and fragment components |
| * are undefined (Undefined components are represented by {@code null}). |
| * |
| * <p> Once a file system created by this provider is {@link FileSystem#close |
| * closed} it is provider-dependent if this method returns a reference to |
| * the closed file system or throws {@link FileSystemNotFoundException}. |
| * If the provider allows a new file system to be created with the same URI |
| * as a file system it previously created then this method throws the |
| * exception if invoked after the file system is closed (and before a new |
| * instance is created by the {@link #newFileSystem newFileSystem} method). |
| * |
| * <p> If a security manager is installed then a provider implementation |
| * may require to check a permission before returning a reference to an |
| * existing file system. In the case of the {@link FileSystems#getDefault |
| * default} file system, no permission check is required. |
| * |
| * @param uri |
| * URI reference |
| * |
| * @return The file system |
| * |
| * @throws IllegalArgumentException |
| * If the pre-conditions for the {@code uri} parameter aren't met |
| * @throws FileSystemNotFoundException |
| * If the file system does not exist |
| * @throws SecurityException |
| * If a security manager is installed and it denies an unspecified |
| * permission. |
| */ |
| public abstract FileSystem getFileSystem(URI uri); |
| |
| /** |
| * Return a {@code Path} object by converting the given {@link URI}. The |
| * resulting {@code Path} is associated with a {@link FileSystem} that |
| * already exists or is constructed automatically. |
| * |
| * <p> The exact form of the URI is file system provider dependent. In the |
| * case of the default provider, the URI scheme is {@code "file"} and the |
| * given URI has a non-empty path component, and undefined query, and |
| * fragment components. The resulting {@code Path} is associated with the |
| * default {@link FileSystems#getDefault default} {@code FileSystem}. |
| * |
| * <p> If a security manager is installed then a provider implementation |
| * may require to check a permission. In the case of the {@link |
| * FileSystems#getDefault default} file system, no permission check is |
| * required. |
| * |
| * @param uri |
| * The URI to convert |
| * |
| * @throws IllegalArgumentException |
| * If the URI scheme does not identify this provider or other |
| * preconditions on the uri parameter do not hold |
| * @throws FileSystemNotFoundException |
| * The file system, identified by the URI, does not exist and |
| * cannot be created automatically |
| * @throws SecurityException |
| * If a security manager is installed and it denies an unspecified |
| * permission. |
| */ |
| public abstract Path getPath(URI uri); |
| |
| /** |
| * Constructs a new {@code FileSystem} to access the contents of a file as a |
| * file system. |
| * |
| * <p> This method is intended for specialized providers of pseudo file |
| * systems where the contents of one or more files is treated as a file |
| * system. The {@code file} parameter is a reference to an existing file |
| * and the {@code env} parameter is a map of provider specific properties to |
| * configure the file system. |
| * |
| * <p> If this provider does not support the creation of such file systems |
| * or if the provider does not recognize the file type of the given file then |
| * it throws {@code UnsupportedOperationException}. The default implementation |
| * of this method throws {@code UnsupportedOperationException}. |
| * |
| * @param file |
| * The file |
| * @param env |
| * A map of provider specific properties to configure the file system; |
| * may be empty |
| * |
| * @return A new file system |
| * |
| * @throws UnsupportedOperationException |
| * If this provider does not support access to the contents as a |
| * file system or it does not recognize the file type of the |
| * given file |
| * @throws IllegalArgumentException |
| * If the {@code env} parameter does not contain properties required |
| * by the provider, or a property value is invalid |
| * @throws IOException |
| * If an I/O error occurs |
| * @throws SecurityException |
| * If a security manager is installed and it denies an unspecified |
| * permission. |
| */ |
| public FileSystem newFileSystem(FileRef file, Map<String,?> env) |
| throws IOException |
| { |
| throw new UnsupportedOperationException(); |
| } |
| |
| /** |
| * Opens or creates a file for reading and/or writing, returning a file |
| * channel to access the file. |
| * |
| * <p> This method is invoked by the {@link FileChannel#open(Path,Set,FileAttribute[]) |
| * FileChannel.open} method to open a file channel. A provider that does not |
| * support all the features required to construct a file channel throws |
| * {@code UnsupportedOperationException}. The default provider is required |
| * to support the creation of file channels. When not overridden, the |
| * default implementation throws {@code UnsupportedOperationException}. |
| * |
| * @param path |
| * The path of the file to open or create |
| * @param options |
| * Options specifying how the file is opened |
| * @param attrs |
| * An optional list of file attributes to set atomically when |
| * creating the file |
| * |
| * @return A new file channel |
| * |
| * @throws IllegalArgumentException |
| * If the set contains an invalid combination of options |
| * @throws UnsupportedOperationException |
| * If this provider that does not support creating file channels, |
| * or an unsupported open option or file attribute is specified |
| * @throws IOException |
| * If an I/O error occurs |
| * @throws SecurityException |
| * In the case of the default file system, the {@link |
| * SecurityManager#checkRead(String)} method is invoked to check |
| * read access if the file is opened for reading. The {@link |
| * SecurityManager#checkWrite(String)} method is invoked to check |
| * write access if the file is opened for writing |
| */ |
| public FileChannel newFileChannel(Path path, |
| Set<? extends OpenOption> options, |
| FileAttribute<?>... attrs) |
| throws IOException |
| { |
| throw new UnsupportedOperationException(); |
| } |
| |
| /** |
| * Opens or creates a file for reading and/or writing, returning an |
| * asynchronous file channel to access the file. |
| * |
| * <p> This method is invoked by the {@link |
| * AsynchronousFileChannel#open(Path,Set,ExecutorService,FileAttribute[]) |
| * AsynchronousFileChannel.open} method to open an asynchronous file channel. |
| * A provider that does not support all the features required to construct |
| * an asynchronous file channel throws {@code UnsupportedOperationException}. |
| * The default provider is required to support the creation of asynchronous |
| * file channels. When not overridden, the default implementation of this |
| * method throws {@code UnsupportedOperationException}. |
| * |
| * @param path |
| * The path of the file to open or create |
| * @param options |
| * Options specifying how the file is opened |
| * @param executor |
| * The thread pool or {@code null} to associate the channel with |
| * the default thread pool |
| * @param attrs |
| * An optional list of file attributes to set atomically when |
| * creating the file |
| * |
| * @return A new asynchronous file channel |
| * |
| * @throws IllegalArgumentException |
| * If the set contains an invalid combination of options |
| * @throws UnsupportedOperationException |
| * If this provider that does not support creating asynchronous file |
| * channels, or an unsupported open option or file attribute is |
| * specified |
| * @throws IOException |
| * If an I/O error occurs |
| * @throws SecurityException |
| * In the case of the default file system, the {@link |
| * SecurityManager#checkRead(String)} method is invoked to check |
| * read access if the file is opened for reading. The {@link |
| * SecurityManager#checkWrite(String)} method is invoked to check |
| * write access if the file is opened for writing |
| */ |
| public AsynchronousFileChannel newAsynchronousFileChannel(Path path, |
| Set<? extends OpenOption> options, |
| ExecutorService executor, |
| FileAttribute<?>... attrs) |
| throws IOException |
| { |
| throw new UnsupportedOperationException(); |
| } |
| } |
