# Class FileSystemProvider

java.lang.Object
java.nio.file.spi.FileSystemProvider

public abstract class FileSystemProvider extends Object
Service-provider class for file systems. The methods defined by the `Files` class will typically delegate to an instance of this class.

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 `URI` `scheme`. The default provider is identified by the URI scheme "file". It creates the `FileSystem` that provides access to the file systems accessible to the Java virtual machine. The `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 `java.nio.file.spi.DefaultFileSystemProvider` is set. In that case, the provider has a one argument constructor whose formal parameter type is `FileSystemProvider`. All other providers have a zero argument constructor that initializes the provider.

A provider is a factory for one or more `FileSystem` instances. Each file system is identified by a `URI` where the URI's scheme matches the provider's `scheme`. The default file system, for example, is identified by the URI `"file:///"`. A memory-based file system, for example, may be identified by a URI such as `"memory:///?name=logfs"`. The `newFileSystem` method may be used to create a file system, and the `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 `newFileSystem` method is invoked. In the case of the default provider, the `FileSystem` is created when the provider is initialized.

All of the methods in this class are safe for use by multiple concurrent threads.

Since:
  1.7

- ## Constructor Summary

  Constructors
  Modifier
  Constructor
  Description
  `protected`
  `FileSystemProvider()`
  Initializes a new instance of this class.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `abstract void`
  `checkAccess(Path path, AccessMode... modes)`
  Checks the existence, and optionally the accessibility, of a file.
  `abstract void`
  `copy(Path source, Path target, CopyOption... options)`
  Copy a file to a target file.
  `abstract void`
  `createDirectory(Path dir, FileAttribute<?>... attrs)`
  Creates a new directory.
  `void`
  `createLink(Path link, Path existing)`
  Creates a new link (directory entry) for an existing file.
  `void`
  `createSymbolicLink(Path link, Path target, FileAttribute<?>... attrs)`
  Creates a symbolic link to a target.
  `abstract void`
  `delete(Path path)`
  Deletes a file.
  `boolean`
  `deleteIfExists(Path path)`
  Deletes a file if it exists.
  `boolean`
  `exists(Path path, LinkOption... options)`
  Tests whether a file exists.
  `abstract <V extends FileAttributeView>
  V`
  `getFileAttributeView(Path path, Class<V> type, LinkOption... options)`
  Returns a file attribute view of a given type.
  `abstract FileStore`
  `getFileStore(Path path)`
  Returns the `FileStore` representing the file store where a file is located.
  `abstract FileSystem`
  `getFileSystem(URI uri)`
  Returns an existing `FileSystem` created by this provider.
  `abstract Path`
  `getPath(URI uri)`
  Return a `Path` object by converting the given `URI`.
  `abstract String`
  `getScheme()`
  Returns the URI scheme that identifies this provider.
  `static List<FileSystemProvider>`
  `installedProviders()`
  Returns a list of the installed file system providers.
  `abstract boolean`
  `isHidden(Path path)`
  Tells whether or not a file is considered hidden.
  `abstract boolean`
  `isSameFile(Path path, Path path2)`
  Tests if two paths locate the same file.
  `abstract void`
  `move(Path source, Path target, CopyOption... options)`
  Move or rename a file to a target file.
  `AsynchronousFileChannel`
  `newAsynchronousFileChannel(Path path, Set<? extends OpenOption> options, ExecutorService executor, FileAttribute<?>... attrs)`
  Opens or creates a file for reading and/or writing, returning an asynchronous file channel to access the file.
  `abstract SeekableByteChannel`
  `newByteChannel(Path path, Set<? extends OpenOption> options, FileAttribute<?>... attrs)`
  Opens or creates a file, returning a seekable byte channel to access the file.
  `abstract DirectoryStream<Path>`
  `newDirectoryStream(Path dir, DirectoryStream.Filter<? super Path> filter)`
  Opens a directory, returning a `DirectoryStream` to iterate over the entries in the directory.
  `FileChannel`
  `newFileChannel(Path path, Set<? extends OpenOption> options, FileAttribute<?>... attrs)`
  Opens or creates a file for reading and/or writing, returning a file channel to access the file.
  `abstract FileSystem`
  `newFileSystem(URI uri, Map<String,?> env)`
  Constructs a new `FileSystem` object identified by a URI.
  `FileSystem`
  `newFileSystem(Path path, Map<String,?> env)`
  Constructs a new `FileSystem` to access the contents of a file as a file system.
  `InputStream`
  `newInputStream(Path path, OpenOption... options)`
  Opens a file, returning an input stream to read from the file.
  `OutputStream`
  `newOutputStream(Path path, OpenOption... options)`
  Opens or creates a file, returning an output stream that may be used to write bytes to the file.
  `abstract <A extends BasicFileAttributes>
  A`
  `readAttributes(Path path, Class<A> type, LinkOption... options)`
  Reads a file's attributes as a bulk operation.
  `abstract Map<String,Object>`
  `readAttributes(Path path, String attributes, LinkOption... options)`
  Reads a set of file attributes as a bulk operation.
  `<A extends BasicFileAttributes>
  A`
  `readAttributesIfExists(Path path, Class<A> type, LinkOption... options)`
  Reads a file's attributes as a bulk operation if it exists.
  `Path`
  `readSymbolicLink(Path link)`
  Reads the target of a symbolic link.
  `abstract void`
  `setAttribute(Path path, String attribute, Object value, LinkOption... options)`
  Sets the value of a file attribute.

  ### Methods declared in class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Constructor Details

  - ### FileSystemProvider

    protected FileSystemProvider()
    Initializes a new instance of this class.

    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.

- ## Method Details

  - ### installedProviders

    public static List<FileSystemProvider> installedProviders()
    Returns a list of the installed file system providers.

    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 `FileSystems` class.

    Returns:
      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

  - ### getScheme

    public abstract String getScheme()
    Returns the URI scheme that identifies this provider.
    Returns:
      The URI scheme

  - ### newFileSystem

    public abstract FileSystem newFileSystem(URI uri, Map<String,?> env) throws IOException
    Constructs a new `FileSystem` object identified by a URI. This method is invoked by the `FileSystems.newFileSystem(URI,Map)` method to open a new file system identified by a URI.

    The `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 `env` parameter is a map of provider specific properties to configure the file system.

    This method throws `FileSystemAlreadyExistsException` if the file system already exists because it was previously created by an invocation of this method. Once a file system is `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.

    Parameters:
      `uri` - URI reference
      `env` - A map of provider specific properties to configure the file system; may be empty
    Returns:
      A new file system
    Throws:
      `IllegalArgumentException` - If the pre-conditions for the `uri` parameter aren't met, or the `env` parameter does not contain properties required by the provider, or a property value is invalid
      `IOException` - An I/O error occurs creating the file system
      `FileSystemAlreadyExistsException` - If the file system has already been created

  - ### getFileSystem

    public abstract FileSystem getFileSystem(URI uri)
    Returns an existing `FileSystem` created by this provider.

    This method returns a reference to a `FileSystem` that was created by invoking the `newFileSystem(URI,Map)` method. File systems created by the `newFileSystem(Path,Map)` method are not returned by this method. The file system is identified by its `URI`. Its exact form is highly provider dependent. In the case of the default provider the URI's path component is `"/"` and the authority, query and fragment components are undefined (Undefined components are represented by `null`).

    Once a file system created by this provider is `closed` it is provider-dependent if this method returns a reference to the closed file system or throws `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 `newFileSystem` method).

    Parameters:
      `uri` - URI reference
    Returns:
      The file system
    Throws:
      `IllegalArgumentException` - If the pre-conditions for the `uri` parameter aren't met
      `FileSystemNotFoundException` - If the file system does not exist

  - ### getPath

    public abstract Path getPath(URI uri)
    Return a `Path` object by converting the given `URI`. The resulting `Path` is associated with a `FileSystem` that already exists or is constructed automatically.

    The exact form of the URI is file system provider dependent. In the case of the default provider, the URI scheme is `"file"` and the given URI has a non-empty path component, and undefined query, and fragment components. The resulting `Path` is associated with the default `default` `FileSystem`.

    Parameters:
      `uri` - The URI to convert
    Returns:
      The resulting `Path`
    Throws:
      `IllegalArgumentException` - If the URI scheme does not identify this provider or other preconditions on the uri parameter do not hold
      `FileSystemNotFoundException` - The file system, identified by the URI, does not exist and cannot be created automatically

  - ### newFileSystem

    public FileSystem newFileSystem(Path path, Map<String,?> env) throws IOException
    Constructs a new `FileSystem` to access the contents of a file as a file system.

    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 `env` parameter is a map of provider specific properties to configure the file system.

    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 `UnsupportedOperationException`. The default implementation of this method throws `UnsupportedOperationException`.

    Parameters:
      `path` - The path to the file
      `env` - A map of provider specific properties to configure the file system; may be empty
    Returns:
      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
      `IllegalArgumentException` - If the `env` parameter does not contain properties required by the provider, or a property value is invalid
      `IOException` - If an I/O error occurs

  - ### newInputStream

    public InputStream newInputStream(Path path, OpenOption... options) throws IOException
    Opens a file, returning an input stream to read from the file. This method works in exactly the manner specified by the `Files.newInputStream(Path, OpenOption...)` method.

    The default implementation of this method opens a channel to the file as if by invoking the `newByteChannel(Path, Set, FileAttribute...)` method and constructs a stream that reads bytes from the channel. This method should be overridden where appropriate.

    Parameters:
      `path` - the path to the file to open
      `options` - options specifying how the file is opened
    Returns:
      a new input stream
    Throws:
      `IllegalArgumentException` - if an invalid combination of options is specified
      `UnsupportedOperationException` - if an unsupported option is specified
      `IOException` - if an I/O error occurs

  - ### newOutputStream

    public OutputStream newOutputStream(Path path, OpenOption... options) throws IOException
    Opens or creates a file, returning an output stream that may be used to write bytes to the file. This method works in exactly the manner specified by the `Files.newOutputStream(Path, OpenOption...)` method.

    The default implementation of this method opens a channel to the file as if by invoking the `newByteChannel(Path, Set, FileAttribute...)` method and constructs a stream that writes bytes to the channel. This method should be overridden where appropriate.

    Parameters:
      `path` - the path to the file to open or create
      `options` - options specifying how the file is opened
    Returns:
      a new output stream
    Throws:
      `IllegalArgumentException` - if `options` contains an invalid combination of options
      `UnsupportedOperationException` - if an unsupported option is specified
      `IOException` - if an I/O error occurs
      `FileAlreadyExistsException` - If a file of that name already exists and the `CREATE_NEW` option is specified (optional specific exception)

  - ### newFileChannel

    public FileChannel newFileChannel(Path path, Set<? extends OpenOption> options, FileAttribute<?>... attrs) throws IOException
    Opens or creates a file for reading and/or writing, returning a file channel to access the file. This method works in exactly the manner specified by the `FileChannel.open` method. A provider that does not support all the features required to construct a file channel throws `UnsupportedOperationException`. The default provider is required to support the creation of file channels. When not overridden, the default implementation throws `UnsupportedOperationException`.
    Parameters:
      `path` - the path of the file to open or create
      `options` - options specifying how the file is opened
      `attrs` - an optional list of file attributes to set atomically when creating the file
    Returns:
      a new file channel
    Throws:
      `IllegalArgumentException` - If the set contains an invalid combination of options
      `UnsupportedOperationException` - If this provider that does not support creating file channels, or an unsupported open option or file attribute is specified
      `FileAlreadyExistsException` - If a file of that name already exists and the `CREATE_NEW` option is specified and the file is being opened for writing (optional specific exception)
      `IOException` - If an I/O error occurs

  - ### newAsynchronousFileChannel

    public AsynchronousFileChannel newAsynchronousFileChannel(Path path, Set<? extends OpenOption> options, ExecutorService executor, FileAttribute<?>... attrs) throws IOException
    Opens or creates a file for reading and/or writing, returning an asynchronous file channel to access the file. This method works in exactly the manner specified by the `AsynchronousFileChannel.open` method. A provider that does not support all the features required to construct an asynchronous file channel throws `UnsupportedOperationException`. The default provider is required to support the creation of asynchronous file channels. When not overridden, the default implementation of this method throws `UnsupportedOperationException`.
    Parameters:
      `path` - the path of the file to open or create
      `options` - options specifying how the file is opened
      `executor` - the thread pool or `null` to associate the channel with the default thread pool
      `attrs` - an optional list of file attributes to set atomically when creating the file
    Returns:
      a new asynchronous file channel
    Throws:
      `IllegalArgumentException` - If the set contains an invalid combination of options
      `UnsupportedOperationException` - If this provider that does not support creating asynchronous file channels, or an unsupported open option or file attribute is specified
      `FileAlreadyExistsException` - If a file of that name already exists and the `CREATE_NEW` option is specified and the file is being opened for writing (optional specific exception)
      `IOException` - If an I/O error occurs

  - ### newByteChannel

    public abstract SeekableByteChannel newByteChannel(Path path, Set<? extends OpenOption> options, FileAttribute<?>... attrs) throws IOException
    Opens or creates a file, returning a seekable byte channel to access the file. This method works in exactly the manner specified by the `Files.newByteChannel(Path,Set,FileAttribute[])` method.
    Parameters:
      `path` - the path to the file to open or create
      `options` - options specifying how the file is opened
      `attrs` - an optional list of file attributes to set atomically when creating the file
    Returns:
      a new seekable byte channel
    Throws:
      `IllegalArgumentException` - if the set contains an invalid combination of options
      `UnsupportedOperationException` - if an unsupported open option is specified or the array contains attributes that cannot be set atomically when creating the file
      `FileAlreadyExistsException` - If a file of that name already exists and the `CREATE_NEW` option is specified and the file is being opened for writing (optional specific exception)
      `IOException` - if an I/O error occurs

  - ### newDirectoryStream

    public abstract DirectoryStream<Path> newDirectoryStream(Path dir, DirectoryStream.Filter<? super Path> filter) throws IOException
    Opens a directory, returning a `DirectoryStream` to iterate over the entries in the directory. This method works in exactly the manner specified by the `Files.newDirectoryStream(java.nio.file.Path, java.nio.file.DirectoryStream.Filter)` method.
    Parameters:
      `dir` - the path to the directory
      `filter` - the directory stream filter
    Returns:
      a new and open `DirectoryStream` object
    Throws:
      `NotDirectoryException` - if the file could not otherwise be opened because it is not a directory (optional specific exception)
      `IOException` - if an I/O error occurs

  - ### createDirectory

    public abstract void createDirectory(Path dir, FileAttribute<?>... attrs) throws IOException
    Creates a new directory. This method works in exactly the manner specified by the `Files.createDirectory(Path, FileAttribute...)` method.
    Parameters:
      `dir` - the directory to create
      `attrs` - an optional list of file attributes to set atomically when creating the directory
    Throws:
      `UnsupportedOperationException` - if the array contains an attribute that cannot be set atomically when creating the directory
      `FileAlreadyExistsException` - if a directory could not otherwise be created because a file of that name already exists (optional specific exception)
      `IOException` - if an I/O error occurs or the parent directory does not exist

  - ### createSymbolicLink

    public void createSymbolicLink(Path link, Path target, FileAttribute<?>... attrs) throws IOException
    Creates a symbolic link to a target. This method works in exactly the manner specified by the `Files.createSymbolicLink(Path, Path, FileAttribute...)` method.

    The default implementation of this method throws `UnsupportedOperationException`.

    Parameters:
      `link` - the path of the symbolic link to create
      `target` - the target of the symbolic link
      `attrs` - the array of attributes to set atomically when creating the symbolic link
    Throws:
      `UnsupportedOperationException` - if the implementation does not support symbolic links or the array contains an attribute that cannot be set atomically when creating the symbolic link
      `FileAlreadyExistsException` - if a file with the name already exists (optional specific exception)
      `IOException` - if an I/O error occurs

  - ### createLink

    public void createLink(Path link, Path existing) throws IOException
    Creates a new link (directory entry) for an existing file. This method works in exactly the manner specified by the `Files.createLink(Path, Path)` method.

    The default implementation of this method throws `UnsupportedOperationException`.

    Parameters:
      `link` - the link (directory entry) to create
      `existing` - a path to an existing file
    Throws:
      `UnsupportedOperationException` - if the implementation does not support adding an existing file to a directory
      `FileAlreadyExistsException` - if the entry could not otherwise be created because a file of that name already exists (optional specific exception)
      `IOException` - if an I/O error occurs

  - ### delete

    public abstract void delete(Path path) throws IOException
    Deletes a file. This method works in exactly the manner specified by the `Files.delete(Path)` method.
    Parameters:
      `path` - the path to the file to delete
    Throws:
      `NoSuchFileException` - if the file does not exist (optional specific exception)
      `DirectoryNotEmptyException` - if the file is a directory and could not otherwise be deleted because the directory is not empty (optional specific exception)
      `IOException` - if an I/O error occurs

  - ### deleteIfExists

    public boolean deleteIfExists(Path path) throws IOException
    Deletes a file if it exists. This method works in exactly the manner specified by the `Files.deleteIfExists(Path)` method.

    The default implementation of this method simply invokes `delete(Path)` ignoring the `NoSuchFileException` when the file does not exist. It may be overridden where appropriate.

    Parameters:
      `path` - the path to the file to delete
    Returns:
      `true` if the file was deleted by this method; `false` if the file could not be deleted because it did not exist
    Throws:
      `DirectoryNotEmptyException` - if the file is a directory and could not otherwise be deleted because the directory is not empty (optional specific exception)
      `IOException` - if an I/O error occurs

  - ### readSymbolicLink

    public Path readSymbolicLink(Path link) throws IOException
    Reads the target of a symbolic link. This method works in exactly the manner specified by the `Files.readSymbolicLink(Path)` method.

    The default implementation of this method throws `UnsupportedOperationException`.

    Parameters:
      `link` - the path to the symbolic link
    Returns:
      The target of the symbolic link
    Throws:
      `UnsupportedOperationException` - if the implementation does not support symbolic links
      `NotLinkException` - if the target could otherwise not be read because the file is not a symbolic link (optional specific exception)
      `IOException` - if an I/O error occurs

  - ### copy

    public abstract void copy(Path source, Path target, CopyOption... options) throws IOException
    Copy a file to a target file. This method works in exactly the manner specified by the `Files.copy(Path,Path,CopyOption[])` method except that both the source and target paths must be associated with this provider.
    Parameters:
      `source` - the path to the file to copy
      `target` - the path to the target file
      `options` - options specifying how the copy should be done
    Throws:
      `UnsupportedOperationException` - if the array contains a copy option that is not supported
      `FileAlreadyExistsException` - if the target file exists but cannot be replaced because the `REPLACE_EXISTING` option is not specified (optional specific exception)
      `DirectoryNotEmptyException` - the `REPLACE_EXISTING` option is specified but the file cannot be replaced because it is a non-empty directory (optional specific exception)
      `IOException` - if an I/O error occurs

  - ### move

    public abstract void move(Path source, Path target, CopyOption... options) throws IOException
    Move or rename a file to a target file. This method works in exactly the manner specified by the `Files.move(Path, Path, CopyOption...)` method except that both the source and target paths must be associated with this provider.
    Parameters:
      `source` - the path to the file to move
      `target` - the path to the target file
      `options` - options specifying how the move should be done
    Throws:
      `UnsupportedOperationException` - if the array contains a copy option that is not supported
      `FileAlreadyExistsException` - if the target file exists but cannot be replaced because the `REPLACE_EXISTING` option is not specified (optional specific exception)
      `DirectoryNotEmptyException` - the `REPLACE_EXISTING` option is specified but the file cannot be replaced because it is a non-empty directory (optional specific exception)
      `AtomicMoveNotSupportedException` - if the options array contains the `ATOMIC_MOVE` option but the file cannot be moved as an atomic file system operation.
      `IOException` - if an I/O error occurs

  - ### isSameFile

    public abstract boolean isSameFile(Path path, Path path2) throws IOException
    Tests if two paths locate the same file. This method works in exactly the manner specified by the `Files.isSameFile(Path, Path)` method.
    Parameters:
      `path` - one path to the file
      `path2` - the other path
    Returns:
      `true` if, and only if, the two paths locate the same file
    Throws:
      `IOException` - if an I/O error occurs

  - ### isHidden

    public abstract boolean isHidden(Path path) throws IOException
    Tells whether or not a file is considered hidden. This method works in exactly the manner specified by the `Files.isHidden(Path)` method.

    This method is invoked by the `isHidden` method.

    Parameters:
      `path` - the path to the file to test
    Returns:
      `true` if the file is considered hidden
    Throws:
      `IOException` - if an I/O error occurs

  - ### getFileStore

    public abstract FileStore getFileStore(Path path) throws IOException
    Returns the `FileStore` representing the file store where a file is located. This method works in exactly the manner specified by the `Files.getFileStore(Path)` method.
    Parameters:
      `path` - the path to the file
    Returns:
      the file store where the file is stored
    Throws:
      `IOException` - if an I/O error occurs

  - ### checkAccess

    public abstract void checkAccess(Path path, AccessMode... modes) throws IOException
    Checks the existence, and optionally the accessibility, of a file.

    This method may be used by the `isReadable`, `isWritable` and `isExecutable` methods to check the accessibility of a file.

    This method checks the existence of a file and that this Java virtual machine has appropriate privileges that would allow it access the file according to all of access modes specified in the `modes` parameter as follows:

    Access Modes
    Value | Description
    --- | ---
    `READ` | Checks that the file exists and that the Java virtual machine has permission to read the file.
    `WRITE` | Checks that the file exists and that the Java virtual machine has permission to write to the file,
    `EXECUTE` | Checks that the file exists and that the Java virtual machine has permission to `execute` the file. The semantics may differ when checking access to a directory. For example, on UNIX systems, checking for `EXECUTE` access checks that the Java virtual machine has permission to search the directory in order to access file or subdirectories.

    If the `modes` parameter is of length zero, then the existence of the file is checked.

    This method follows symbolic links if the file referenced by this object is a symbolic link. Depending on the implementation, this method may require to read file permissions, access control lists, or other file attributes in order to check the effective access to the file. To determine the effective access to a file may require access to several attributes and so in some implementations this method may not be atomic with respect to other file system operations.

    Parameters:
      `path` - the path to the file to check
      `modes` - The access modes to check; may have zero elements
    Throws:
      `UnsupportedOperationException` - an implementation is required to support checking for `READ`, `WRITE`, and `EXECUTE` access. This exception is specified to allow for the `Access` enum to be extended in future releases.
      `NoSuchFileException` - if a file does not exist (optional specific exception)
      `AccessDeniedException` - the requested access would be denied or the access cannot be determined because the Java virtual machine has insufficient privileges or other reasons. (optional specific exception)
      `IOException` - if an I/O error occurs

  - ### getFileAttributeView

    public abstract <V extends FileAttributeView> V getFileAttributeView(Path path, Class<V> type, LinkOption... options)
    Returns a file attribute view of a given type. This method works in exactly the manner specified by the `Files.getFileAttributeView(Path, Class, LinkOption...)` method.
    Type Parameters:
      `V` - The `FileAttributeView` type
    Parameters:
      `path` - the path to the file
      `type` - the `Class` object corresponding to the file attribute view
      `options` - options indicating how symbolic links are handled
    Returns:
      a file attribute view of the specified type, or `null` if the attribute view type is not available

  - ### readAttributes

    public abstract <A extends BasicFileAttributes> A readAttributes(Path path, Class<A> type, LinkOption... options) throws IOException
    Reads a file's attributes as a bulk operation. This method works in exactly the manner specified by the `Files.readAttributes(Path,Class,LinkOption[])` method.
    Type Parameters:
      `A` - The `BasicFileAttributes` type
    Parameters:
      `path` - the path to the file
      `type` - the `Class` of the file attributes required to read
      `options` - options indicating how symbolic links are handled
    Returns:
      the file attributes
    Throws:
      `UnsupportedOperationException` - if an attributes of the given type are not supported
      `IOException` - if an I/O error occurs

  - ### readAttributes

    public abstract Map<String,Object> readAttributes(Path path, String attributes, LinkOption... options) throws IOException
    Reads a set of file attributes as a bulk operation. This method works in exactly the manner specified by the `Files.readAttributes(Path,String,LinkOption[])` method.
    Parameters:
      `path` - the path to the file
      `attributes` - the attributes to read
      `options` - options indicating how symbolic links are handled
    Returns:
      a map of the attributes returned; may be empty. The map's keys are the attribute names, its values are the attribute values
    Throws:
      `UnsupportedOperationException` - if the attribute view is not available
      `IllegalArgumentException` - if no attributes are specified or an unrecognized attributes is specified
      `IOException` - If an I/O error occurs

  - ### setAttribute

    public abstract void setAttribute(Path path, String attribute, Object value, LinkOption... options) throws IOException
    Sets the value of a file attribute. This method works in exactly the manner specified by the `Files.setAttribute(Path, String, Object, LinkOption...)` method.
    Parameters:
      `path` - the path to the file
      `attribute` - the attribute to set
      `value` - the attribute value
      `options` - options indicating how symbolic links are handled
    Throws:
      `UnsupportedOperationException` - if the attribute view is not available
      `IllegalArgumentException` - if the attribute name is not specified, or is not recognized, or the attribute value is of the correct type but has an inappropriate value
      `ClassCastException` - If the attribute value is not of the expected type or is a collection containing elements that are not of the expected type
      `IOException` - If an I/O error occurs

  - ### exists

    public boolean exists(Path path, LinkOption... options)
    Tests whether a file exists. This method works in exactly the manner specified by the `Files.exists(Path, LinkOption...)` method.
    Implementation Requirements:
      The default implementation of this method invokes the `checkAccess(Path, AccessMode...)` method when symbolic links are followed. If the option `NOFOLLOW_LINKS` is present then symbolic links are not followed and the method `readAttributes(Path, Class, LinkOption...)` is called to determine whether a file exists.
    Parameters:
      `path` - the path to the file to test
      `options` - options indicating how symbolic links are handled
    Returns:
      `true` if the file exists; `false` if the file does not exist or its existence cannot be determined.
    Since:
      20

  - ### readAttributesIfExists

    public <A extends BasicFileAttributes> A readAttributesIfExists(Path path, Class<A> type, LinkOption... options) throws IOException
    Reads a file's attributes as a bulk operation if it exists.

    The `type` parameter is the type of the attributes required and this method returns an instance of that type if supported. All implementations support a basic set of file attributes and so invoking this method with a `type` parameter of `BasicFileAttributes.class` will not throw `UnsupportedOperationException`.

    The `options` array may be used to indicate how symbolic links are handled for the case that the file is a symbolic link. By default, symbolic links are followed and the file attribute of the final target of the link is read. If the option `NOFOLLOW_LINKS` is present then symbolic links are not followed.

    It is implementation specific if all file attributes are read as an atomic operation with respect to other file system operations.

    Implementation Requirements:
      The default implementation of this method invokes the `readAttributes(Path, Class, LinkOption...)` method to read the file's attributes.
    Type Parameters:
      `A` - The `BasicFileAttributes` type
    Parameters:
      `path` - the path to the file
      `type` - the `Class` of the file attributes required to read
      `options` - options indicating how symbolic links are handled
    Returns:
      the file attributes or null if the file does not exist
    Throws:
      `UnsupportedOperationException` - if an attributes of the given type are not supported
      `IOException` - if an I/O error occurs
    Since:
      20