com.github.fge.filesystem.attributes

Class FileAttributesFactory

java.lang.Object

com.github.fge.filesystem.attributes.FileAttributesFactory

@ParametersAreNonnullByDefault
public class FileAttributesFactory
extends Object

File attributes factory

This class allows you to register attribute providers and add implementations. You must provide one such factory per filesystem and at least provide an implementation of the basic file attributes, as required by the API.

It is also responsible for generating instances of attribute provider classes at runtime (using MethodHandles).

You must extend this class, provide the metadata class used when building attribute providers and then register your attribute provider classes using addImplementation(String, Class); you can even register your own attribute views using addDescriptor(AttributesDescriptor) (do this before registering implementations).

See this pagefor a sample use.

Unless otherwise noted, all methods of this class will throw a NullPointerException if a null argument is passed.

See Also:

FileSystemDriverBase

Constructor Summary

Constructors

Constructor and Description
FileAttributesFactory() Constructor to extend

Method Summary

Methods

Modifier and Type	Method and Description
protected void	addDescriptor(AttributesDescriptor descriptor) Add an attribute view descriptor
protected void	addImplementation(String name, Class<? extends FileAttributesProvider> providerClass) Add an implementation for a given attribute view
Map<String,AttributesDescriptor>	getDescriptors() Return a list of all attribute descriptors registered with this factory
<A extends BasicFileAttributes> A	getFileAttributes(Class<A> targetClass, Object metadata) Generate an attribute provider matching the target attributes class
<V extends FileAttributeView> V	getFileAttributeView(Class<V> targetClass, Object metadata) Generate an attribute provider implementing the target attribute view class
FileAttributesProvider	getProvider(String name, Object metadata) Instantiate a new provider for a given attribute view with the given metadata
protected void	setMetadataClass(Class<?> metadataClass) Set the metadata class used when constructing new attribute provider instances
boolean	supportsFileAttributeView(Class<? extends FileAttributeView> viewClass)
boolean	supportsFileAttributeView(String name)

Methods inherited from class java.lang.Object

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

Constructor Detail

FileAttributesFactory

public FileAttributesFactory()

Constructor to extend

Method Detail

supportsFileAttributeView

public final boolean supportsFileAttributeView(Class<? extends FileAttributeView> viewClass)

supportsFileAttributeView

public final boolean supportsFileAttributeView(String name)

getDescriptors

@Nonnull
public final Map<String,AttributesDescriptor> getDescriptors()

Return a list of all attribute descriptors registered with this factory

Returns:

an immutable map (where keys are the names of the views and values are the descriptors themselves)

getProvider

@Nullable
public final FileAttributesProvider getProvider(String name,
                                          Object metadata)
                                         throws IOException

Instantiate a new provider for a given attribute view with the given metadata

Parameters:

name - the attribute view name

metadata - the metadata to use to instantiate the provider

Returns:

the provider, or null if this view is not supported

Throws:

IOException - failed to generate the provider

See Also:

FileSystemDriverBase.readAttributes(Path, String, LinkOption...), FileSystemDriverBase.setAttribute(Path, String, Object, LinkOption...), MethodHandle.invoke(Object...)

getFileAttributeView

@Nullable
public final <V extends FileAttributeView> V getFileAttributeView(Class<V> targetClass,
                                                            Object metadata)
                                                       throws IOException

Generate an attribute provider implementing the target attribute view class

Note that the returned target may not "strictly" implement the view; it may be a subclass of it. For instance, if you only have an implementation for DosFileAttributeView, this is what will be returned if you ask for a BasicFileAttributeView (since the former extends the latter).

Type Parameters:

V - type parameter of the target view

Parameters:

targetClass - the target view

metadata - the metadata to generate the provider with

Returns:

a matching provider downcast to the given class, or null if this view is not supported

Throws:

IOException - failed to generate the attribute provider

See Also:

FileSystemDriverBase.getFileAttributeView(Path, Class, LinkOption...)

getFileAttributes

@Nullable
public final <A extends BasicFileAttributes> A getFileAttributes(Class<A> targetClass,
                                                           Object metadata)
                                                      throws IOException

Generate an attribute provider matching the target attributes class

Note that the returned target may not "strictly" implement the attribute class; it may be a subclass of it. For instance, if you only have an implementation for DosFileAttributes, this is what will be returned if you ask for a BasicFileAttributes (since the former extends the latter).

Type Parameters:

A - type parameter of the target attribute class

Parameters:

targetClass - the target attribute class

metadata - the metadata to generate the provider with

Returns:

a matching provider downcast to the given class, or null if this attribute class is not supported

Throws:

IOException - failed to generate the attribute provider

See Also:

FileSystemDriverBase.readAttributes(Path, Class, LinkOption...)

setMetadataClass

protected final void setMetadataClass(Class<?> metadataClass)

Set the metadata class used when constructing new attribute provider instances

This method must be called before registering attribute provider implementations.

Parameters:

metadataClass - the class

Throws:

IllegalArgumentException - a metadata class has already been set

See Also:

FileSystemDriver.getPathMetadata(Path)

addDescriptor

protected final void addDescriptor(AttributesDescriptor descriptor)

Add an attribute view descriptor

Parameters:

descriptor - the descriptor to add

Throws:

IllegalArgumentException - a descriptor by that name is already registered

See Also:

AttributesDescriptor.getName()

addImplementation

protected final void addImplementation(String name,
                     Class<? extends FileAttributesProvider> providerClass)

Add an implementation for a given attribute view

Parameters:

name - the name of the view

providerClass - the attribute provider class

Throws:

IllegalArgumentException - no metadata class has been set, or no descriptor associated with that view

InvalidAttributeProviderException - provided class is not a concrete class; or no suitable constructor has been found; or it is not a subclass of the associated view class and (if any) attribute class

See Also:

AttributesDescriptor.getViewClass(), AttributesDescriptor.getAttributeClass()