- java.lang.Object
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- java.nio.file.FileStore
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public abstract class FileStore extends Object
Storage for files. AFileStorerepresents a storage pool, device, partition, volume, concrete file system or other implementation specific means of file storage. TheFileStorefor where a file is stored is obtained by invoking thegetFileStoremethod, or all file stores can be enumerated by invoking thegetFileStoresmethod.In addition to the methods defined by this class, a file store may support one or more
FileStoreAttributeViewclasses that provide a read-only or updatable view of a set of file store attributes.- Since:
- 1.7
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Constructor Summary
Constructors Modifier Constructor Description protectedFileStore()Initializes a new instance of this class.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description abstract ObjectgetAttribute(String attribute)Reads the value of a file store attribute.longgetBlockSize()Returns the number of bytes per block in this file store.abstract <V extends FileStoreAttributeView>
VgetFileStoreAttributeView(Class<V> type)Returns aFileStoreAttributeViewof the given type.abstract longgetTotalSpace()Returns the size, in bytes, of the file store.abstract longgetUnallocatedSpace()Returns the number of unallocated bytes in the file store.abstract longgetUsableSpace()Returns the number of bytes available to this Java virtual machine on the file store.abstract booleanisReadOnly()Tells whether this file store is read-only.abstract Stringname()Returns the name of this file store.abstract booleansupportsFileAttributeView(Class<? extends FileAttributeView> type)Tells whether or not this file store supports the file attributes identified by the given file attribute view.abstract booleansupportsFileAttributeView(String name)Tells whether or not this file store supports the file attributes identified by the given file attribute view.abstract Stringtype()Returns the type of this file store.
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Method Detail
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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
toStringmethod.- Returns:
- the name of this file store
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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:
- a string representing the type of this file store
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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 anIOExceptionto be thrown.- Returns:
trueif, and only if, this file store is read-only
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getTotalSpace
public abstract long getTotalSpace() throws IOExceptionReturns the size, in bytes, of the file store.- Returns:
- the size of the file store, in bytes
- Throws:
IOException- if an I/O error occurs
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getUsableSpace
public abstract long getUsableSpace() throws IOExceptionReturns 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:
- the number of bytes available
- Throws:
IOException- if an I/O error occurs
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getBlockSize
public long getBlockSize() throws IOExceptionReturns 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:
- a positive value representing the block size of this file store, in bytes
- Throws:
IOException- if an I/O error occursUnsupportedOperationException- if the operation is not supported- Since:
- 10
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getUnallocatedSpace
public abstract long getUnallocatedSpace() throws IOExceptionReturns 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:
- the number of unallocated bytes
- Throws:
IOException- if an I/O error occurs
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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
BasicFileAttributeViewwill always returntrue. 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- the file attribute view type- Returns:
trueif, and only if, the file attribute view is supported
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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 returntrue. 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- thenameof file attribute view- Returns:
trueif, and only if, the file attribute view is supported
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getFileStoreAttributeView
public abstract <V extends FileStoreAttributeView> V getFileStoreAttributeView(Class<V> type)
Returns aFileStoreAttributeViewof 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
typeparameter is the type of the attribute view required and the method returns an instance of that type if supported.- Type Parameters:
V- TheFileStoreAttributeViewtype- Parameters:
type- theClassobject corresponding to the attribute view- Returns:
- a file store attribute view of the specified type or
nullif the attribute view is not available
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getAttribute
public abstract Object getAttribute(String attribute) throws IOException
Reads the value of a file store attribute.The
attributeparameter identifies the attribute to be read and takes the form:view-name:attribute-name
where the character':'stands for itself.view-name is the
nameof aAttributeViewthat 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- the attribute to read- Returns:
- the attribute value;
nullmay be valid for some attributes - Throws:
UnsupportedOperationException- 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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