public abstract class FileStore extends Object
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.
| Modifier | Constructor | Description |
|---|---|---|
protected |
Initializes a new instance of this class. |
| Modifier and Type | Method | Description |
|---|---|---|
abstract Object |
getAttribute |
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> |
getFileStoreAttributeView |
Returns a FileStoreAttributeView of the given type. |
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 |
Tells whether or not this file store supports the file attributes identified by the given file attribute view. |
abstract boolean |
supportsFileAttributeView |
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. |
protected FileStore()
public abstract String name()
The string returned by this method may differ from the string returned by the toString method.
public abstract String type()
public abstract boolean isReadOnly()
IOException to be thrown.true if, and only if, this file store is read-onlypublic abstract long getTotalSpace() throws IOException
Long.MAX_VALUE, then Long.MAX_VALUE will be returned.IOException - if an I/O error occurspublic abstract long getUsableSpace() throws IOException
Long.MAX_VALUE, then Long.MAX_VALUE will be returned. 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.
IOException - if an I/O error occurspublic abstract long getUnallocatedSpace() throws IOException
Long.MAX_VALUE, then Long.MAX_VALUE will be returned. 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.
IOException - if an I/O error occurspublic long getBlockSize() throws IOException
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.
UnsupportedOperationException.IOException - if an I/O error occursUnsupportedOperationException - if the operation is not supportedpublic abstract boolean supportsFileAttributeView(Class<? extends FileAttributeView> type)
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.
type - the file attribute view typetrue if, and only if, the file attribute view is supportedpublic abstract boolean supportsFileAttributeView(String name)
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.
name - the name of file attribute viewtrue if, and only if, the file attribute view is supportedpublic abstract <V extends FileStoreAttributeView> V getFileStoreAttributeView(Class<V> type)
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.
V - The FileStoreAttributeView typetype - the Class object corresponding to the attribute viewnull if the attribute view is not availablepublic abstract Object getAttribute(String attribute) throws IOException
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");
attribute - the attribute to readnull may be valid for some attributesUnsupportedOperationException - if the attribute view is not available or it does not support reading the attributeIOException - if an I/O error occurs
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/FileStore.html