Package com.github.fge.filesystem.attributes

File attributes and attribute views

See: Description

Package com.github.fge.filesystem.attributes Description

File attributes and attribute views

Warning: attribute loading

Right now, there is a bug with the way classes in this package implement attribute views; they are supposedly only loaded when you need them (Files.getFileAttributeView(java.nio.file.Path, java.lang.Class, java.nio.file.LinkOption...) does not throw an exception), however this package loads them eagerly. At this moment, if attributes fail to load, an UncaughtIOException (unchecked) is thrown.

This will be fixed in a future release.

What this package does

This package provides everything you need to implement attributes; not only the ones defined by the JDK, but also your own. Attribute dispatch (creation, string handling etc) is already done for you in FileSystemDriverBase; you only have to implement attributes and provide a FileAttributesFactory.

Implementing attributes

This package wraps all attribute views in provider classes. After you implement the attribute providers you need, you will need to extend FileAttributesFactory and register your attribute providers. For instance:

     public final class MyFileAttributesProvider
         extends FileAttributesProvider
     {
         public MyFileAttributesProvider()
         {
             // You MUST do this first
             setMetadataClass(MyMetadataClass.class);
             addImplementation("basic", MyBasicFileAttributesProvider.class);
         }
     }

Reminder: the API requires that basic attributes be implemented by all filesystem implementations.

Implementing custom attributes

You are not limited to the basic types provided by the JDK; you can also provide your own attributes. For this, you should first have an implementation for your attributes (either by extending an existing attribute provider class or by directly extending FileAttributesProvider), choose a name for your attribute view and create an AttributesDescriptor for it. You will then register it to the factory -- do this before registering an implementation. The default factory already includes all descriptors for attributes defined by the JDK.

Example:

     public final class MyFileAttributesProvider
         extends FileAttributesProvider
     {
         public MyFileAttributesProvider()
         {
             // You MUST do this first
             setMetadataClass(MyMetadataClass.class);
             addDescriptor(new MyCoolAttributesDescriptor());
             // Provided that the name returned by the descriptor is "cool"
             addImplementation("cool", MyCoolFileAttributesProvider.class);
         }
     }

Note that this is an error to try and register a descriptor with the same name twice.