FileStore
public
abstract
class
FileStore
extends Object
java.lang.Object | |
↳ | java.nio.file.FileStore |
Storage for files. A FileStore
represents a storage pool, device,
partition, volume, concrete file system or other implementation specific means
of file storage. The FileStore
for where a file is stored is obtained
by invoking the getFileStore
method, or all file
stores can be enumerated by invoking the getFileStores
method.
In addition to the methods defined by this class, a file store may support
one or more FileStoreAttributeView
classes
that provide a read-only or updatable view of a set of file store attributes.
Summary
Protected constructors | |
---|---|
FileStore()
Initializes a new instance of this class. |
Public methods | |
---|---|
abstract
Object
|
getAttribute(String attribute)
Reads the value of a file store attribute. |
long
|
getBlockSize()
Returns the number of bytes per block in this file store. |
abstract
<V extends FileStoreAttributeView>
V
|
getFileStoreAttributeView(Class<V> type)
Returns a |
abstract
long
|
getTotalSpace()
Returns the size, in bytes, of the file store. |
abstract
long
|
getUnallocatedSpace()
Returns the number of unallocated bytes in the file store. |
abstract
long
|
getUsableSpace()
Returns the number of bytes available to this Java virtual machine on the file store. |
abstract
boolean
|
isReadOnly()
Tells whether this file store is read-only. |
abstract
String
|
name()
Returns the name of this file store. |
abstract
boolean
|
supportsFileAttributeView(String name)
Tells whether or not this file store supports the file attributes identified by the given file attribute view. |
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. |
abstract
String
|
type()
Returns the type of this file store. |
Inherited methods | |
---|---|
Protected constructors
Public methods
getAttribute
public abstract Object getAttribute (String attribute)
Reads the value of a file store attribute.
The attribute
parameter identifies the attribute to be read
and takes the form:
view-name:attribute-namewhere the character
':'
stands for itself.
view-name is the name
of
a AttributeView
that identifies a set of file attributes.
attribute-name is the name of the attribute.
Usage Example: Suppose we want to know if ZFS compression is enabled (assuming the "zfs" view is supported):
boolean compression = (Boolean)fs.getAttribute("zfs:compression");
Parameters | |
---|---|
attribute |
String : the attribute to read |
Returns | |
---|---|
Object |
the attribute value; null may be valid for some
attributes |
Throws | |
---|---|
UnsupportedOperationException |
if the attribute view is not available or it does not support reading the attribute |
IOException |
if an I/O error occurs |
getBlockSize
public long getBlockSize ()
Returns the number of bytes per block in this file store.
File storage is typically organized into discrete sequences of bytes called blocks. A block is the smallest storage unit of a file store. Every read and write operation is performed on a multiple of blocks.
Implementation Requirements:
- The implementation in this class throws an
UnsupportedOperationException
.
Returns | |
---|---|
long |
a positive value representing the block size of this file store, in bytes |
Throws | |
---|---|
IOException |
if an I/O error occurs |
UnsupportedOperationException |
if the operation is not supported |
getFileStoreAttributeView
public abstract V getFileStoreAttributeView (Class<V> type)
Returns a FileStoreAttributeView
of the given type.
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 type
parameter is the type of the attribute view required and
the method returns an instance of that type if supported.
Parameters | |
---|---|
type |
Class : the Class object corresponding to the attribute view |
Returns | |
---|---|
V |
a file store attribute view of the specified type or
null if the attribute view is not available |
getTotalSpace
public abstract long getTotalSpace ()
Returns the size, in bytes, of the file store.
Returns | |
---|---|
long |
the size of the file store, in bytes |
Throws | |
---|---|
IOException |
if an I/O error occurs |
getUnallocatedSpace
public abstract long getUnallocatedSpace ()
Returns the number of unallocated bytes in the file store.
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.
Returns | |
---|---|
long |
the number of unallocated bytes |
Throws | |
---|---|
IOException |
if an I/O error occurs |
getUsableSpace
public abstract long getUsableSpace ()
Returns the number of bytes available to this Java virtual machine on the file store.
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.
Returns | |
---|---|
long |
the number of bytes available |
Throws | |
---|---|
IOException |
if an I/O error occurs |
isReadOnly
public abstract boolean isReadOnly ()
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 IOException
to be thrown.
Returns | |
---|---|
boolean |
true if, and only if, this file store is read-only |
name
public abstract String name ()
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.
The string returned by this method may differ from the string
returned by the toString
method.
Returns | |
---|---|
String |
the name of this file store |
supportsFileAttributeView
public abstract boolean supportsFileAttributeView (String name)
Tells whether or not this file store supports the file attributes identified by the given file attribute view.
Invoking this method to test if the file store supports BasicFileAttributeView
, identified by the name "basic
" will
always return 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.
Parameters | |
---|---|
name |
String : the name of file attribute view |
Returns | |
---|---|
boolean |
true if, and only if, the file attribute view is
supported |
supportsFileAttributeView
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.
Invoking this method to test if the file store supports BasicFileAttributeView
will always return 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.
Parameters | |
---|---|
type |
Class : the file attribute view type |
Returns | |
---|---|
boolean |
true if, and only if, the file attribute view is
supported |
type
public abstract String type ()
Returns the type 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.
Returns | |
---|---|
String |
a string representing the type of this file store |