org.apache.lucene.store
Class Directory
public abstract
class
Directory
extends Object
A Directory is a flat list of files. Files may be written once, when they
are created. Once a file is created it may only be opened for read, or
deleted. Random access is permitted both when reading and writing.
Java's i/o APIs not used directly, but rather all i/o is
through this API. This permits things such as:
- implementation of RAM-based indices;
- implementation indices stored in a database, via JDBC;
- implementation of an index as a single file;
Directory locking is implemented by an instance of
LockFactory, and can be changed for each Directory
instance using
Directory.
Author: Doug Cutting
Method Summary |
void | clearLock(String name)
Attempt to clear (forcefully unlock and remove) the
specified lock. |
abstract void | close() Closes the store. |
static void | copy(Directory src, Directory dest, boolean closeDirSrc)
Copy contents of a directory src to a directory dest.
|
abstract IndexOutput | createOutput(String name) Creates a new, empty file in the directory with the given name.
|
abstract void | deleteFile(String name) Removes an existing file in the directory. |
abstract boolean | fileExists(String name) Returns true iff a file with the given name exists. |
abstract long | fileLength(String name) Returns the length of a file in the directory. |
abstract long | fileModified(String name) Returns the time the named file was last modified. |
LockFactory | getLockFactory()
Get the LockFactory that this Directory instance is
using for its locking implementation. |
String | getLockID()
Return a string identifier that uniquely differentiates
this Directory instance from other Directory instances.
|
abstract String[] | list() Returns an array of strings, one for each file in the
directory. |
Lock | makeLock(String name) |
abstract IndexInput | openInput(String name) Returns a stream reading an existing file. |
IndexInput | openInput(String name, int bufferSize) Returns a stream reading an existing file, with the
specified read buffer size. |
abstract void | renameFile(String from, String to) Renames an existing file in the directory.
|
void | setLockFactory(LockFactory lockFactory)
Set the LockFactory that this Directory instance should
use for its locking implementation. |
abstract void | touchFile(String name) Set the modified time of an existing file to now. |
Holds the LockFactory instance (implements locking for
this Directory instance).
public void clearLock(String name)
Attempt to clear (forcefully unlock and remove) the
specified lock. Only call this at a time when you are
certain this lock is no longer in use.
Parameters: name name of the lock to be cleared.
public abstract void close()
Closes the store.
Copy contents of a directory src to a directory dest.
If a file in src already exists in dest then the
one in dest will be blindly overwritten.
Parameters: src source directory dest destination directory closeDirSrc if true
, call close method on source directory
Throws: IOException
Creates a new, empty file in the directory with the given name.
Returns a stream writing this file.
public abstract void deleteFile(String name)
Removes an existing file in the directory.
public abstract boolean fileExists(String name)
Returns true iff a file with the given name exists.
public abstract long fileLength(String name)
Returns the length of a file in the directory.
public abstract long fileModified(String name)
Returns the time the named file was last modified.
Get the LockFactory that this Directory instance is
using for its locking implementation. Note that this
may be null for Directory implementations that provide
their own locking implementation.
public String getLockID()
Return a string identifier that uniquely differentiates
this Directory instance from other Directory instances.
This ID should be the same if two Directory instances
(even in different JVMs and/or on different machines)
are considered "the same index". This is how locking
"scopes" to the right index.
public abstract String[] list()
Returns an array of strings, one for each file in the
directory. This method may return null (for example for
FSDirectory if the underlying directory doesn't
exist in the filesystem or there are permissions
problems).
public
Lock makeLock(String name)
Construct a
Lock.
Parameters: name the name of the lock file
Returns a stream reading an existing file.
public
IndexInput openInput(String name, int bufferSize)
Returns a stream reading an existing file, with the
specified read buffer size. The particular Directory
implementation may ignore the buffer size. Currently
the only Directory implementations that respect this
parameter are
FSDirectory and
CompoundFileReader.
public abstract void renameFile(String from, String to)
Deprecated:
Renames an existing file in the directory.
If a file already exists with the new name, then it is replaced.
This replacement is not guaranteed to be atomic.
Set the LockFactory that this Directory instance should
use for its locking implementation. Each * instance of
LockFactory should only be used for one directory (ie,
do not share a single instance across multiple
Directories).
Parameters: lockFactory instance of LockFactory.
public abstract void touchFile(String name)
Set the modified time of an existing file to now.
Copyright © 2000-2007 Apache Software Foundation. All Rights Reserved.