In addition to the methods defined by this class, a file store may support * one or more {@link FileStoreAttributeView FileStoreAttributeView} classes * that provide a read-only or updatable view of a set of file store attributes. * * @since 1.7 */ public abstract class FileStore { /** * Initializes a new instance of this class. */ protected FileStore() { } /** * 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 {@link Object#toString() toString} method. * * @return the name of this file store */ public abstract String name(); /** * 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. * * @return a string representing the type of this file store */ public abstract String type(); /** * 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 {@code IOException} to be thrown. * * @return {@code true} if, and only if, this file store is read-only */ public abstract boolean isReadOnly(); /** * Returns the size, in bytes, of the file store. * * @return the size of the file store, in bytes * * @throws IOException * if an I/O error occurs */ public abstract long getTotalSpace() throws IOException; /** * 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. * * @return the number of bytes available * * @throws IOException * if an I/O error occurs */ public abstract long getUsableSpace() throws IOException; /** * Returns block size in Bytes to this Java virtual machine on the file * store. * * @return block size * * @throws IOException * if an I/O error occurs */ public abstract int getBlockSize() throws IOException; /** * 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. * * @return the number of unallocated bytes * * @throws IOException * if an I/O error occurs */ public abstract long getUnallocatedSpace() throws IOException; /** * 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 {@link * BasicFileAttributeView} will always return {@code 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. * * @param type * the file attribute view type * * @return {@code true} if, and only if, the file attribute view is * supported */ public abstract boolean supportsFileAttributeView(Class 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 {@link * BasicFileAttributeView}, identified by the name "{@code basic}" will * always return {@code 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. * * @param name * the {@link FileAttributeView#name name} of file attribute view * * @return {@code true} if, and only if, the file attribute view is * supported */ public abstract boolean supportsFileAttributeView(String name); /** * Returns a {@code 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 {@code type} parameter is the type of the attribute view required and
* the method returns an instance of that type if supported.
*
* @param The {@code attribute} parameter identifies the attribute to be read
* and takes the form:
* view-name is the {@link FileStoreAttributeView#name name} of
* a {@link FileStore 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):
*
* view-name:attribute-name
*
* where the character {@code ':'} stands for itself.
*
*
* boolean compression = (Boolean)fs.getAttribute("zfs:compression");
*
*
* @param attribute
* the attribute to read
* @return the attribute value; {@code null} may be valid for some
* attributes
*
* @throws UnsupportedOperationException
* if the attribute view is not available or it does not support
* reading the attribute
* @throws IOException
* if an I/O error occurs
*/
public abstract Object getAttribute(String attribute) throws IOException;
}