org.apache.derby.impl.io
Class URLFile

java.lang.Object
  org.apache.derby.impl.io.InputStreamFile
      org.apache.derby.impl.io.URLFile

All Implemented Interfaces:

StorageFile

class URLFile

extends InputStreamFile

This class provides a class path based implementation of the StorageFile interface. It is used by the database engine to access persistent data and transaction logs under the classpath subsubprotocol.

Field Summary

(package private) int	nameStart
(package private) java.lang.String	path
private URLStorageFactory	storageFactory

Fields inherited from interface org.apache.derby.io.StorageFile

EXCLUSIVE_FILE_LOCK, EXCLUSIVE_FILE_LOCK_NOT_AVAILABLE, NO_FILE_LOCK_SUPPORT

Constructor Summary

(package private)	URLFile(URLFile dir, java.lang.String name)
(package private)	URLFile(URLStorageFactory storageFactory, java.lang.String path)
private	URLFile(URLStorageFactory storageFactory, java.lang.String child, int pathLen)
(package private)	URLFile(URLStorageFactory storageFactory, java.lang.String parent, java.lang.String name)

Method Summary

boolean	canWrite() Determine whether the named file is writable.
boolean	createNewFile() If the named file does not already exist then create it as an empty normal file.
boolean	delete() Deletes the named file or empty directory.
boolean	deleteAll() Deletes the named file and, if it is a directory, all the files and directories it contains.
boolean	equals(java.lang.Object other)
boolean	exists() Tests whether the named file exists.
java.lang.String	getCanonicalPath() Converts this StorageFile into a canonical pathname string.
int	getExclusiveFileLock() Get an exclusive lock with this name.
java.io.InputStream	getInputStream() Creates an input stream from a file name.
java.lang.String	getName()
java.io.OutputStream	getOutputStream() Creates an output stream from a file name.
java.io.OutputStream	getOutputStream(boolean append) Creates an output stream from a file name.
StorageFile	getParentDir() Get the name of the parent directory if this name includes a parent.
(package private) StorageFile	getParentDir(int pathLen) Get the parent of this file.
java.lang.String	getPath() Converts this StorageFile into a pathname string.
StorageRandomAccessFile	getRandomAccessFile(java.lang.String mode) Get a random access file.
int	hashCode()
boolean	isDirectory() Tests whether the named file is a directory, or not.
long	length() Returns the length of the named file if it is not a directory.
java.lang.String[]	list() Get the names of all files and sub-directories in the directory named by this path name.
boolean	mkdir() Creates the named directory.
boolean	mkdirs() Creates the named directory, and all nonexistent parent directories.
void	releaseExclusiveFileLock() Release the resource associated with an earlier acquired exclusive lock
boolean	renameTo(StorageFile newName) Rename the file denoted by this name.
boolean	setReadOnly() Make the named file or directory read-only.
java.lang.String	toString() Get the file name for diagnostic purposes.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

storageFactory

private final URLStorageFactory storageFactory

path

final java.lang.String path

nameStart

final int nameStart

Constructor Detail

URLFile

URLFile(URLStorageFactory storageFactory,
        java.lang.String path)

URLFile

URLFile(URLStorageFactory storageFactory,
        java.lang.String parent,
        java.lang.String name)

URLFile

URLFile(URLFile dir,
        java.lang.String name)

URLFile

private URLFile(URLStorageFactory storageFactory,
                java.lang.String child,
                int pathLen)

Method Detail

exists

public boolean exists()

Tests whether the named file exists.

Specified by:

exists in interface StorageFile

Specified by:

exists in class InputStreamFile

Returns:

true if the named file exists, false if not.

getParentDir

StorageFile getParentDir(int pathLen)

Get the parent of this file.

Specified by:

getParentDir in class InputStreamFile

Parameters:

pathLen - the length of the parent's path name.

getInputStream

public java.io.InputStream getInputStream()
                                   throws java.io.FileNotFoundException

Creates an input stream from a file name.

Specified by:

getInputStream in interface StorageFile

Specified by:

getInputStream in class InputStreamFile

Returns:

an input stream suitable for reading from the file.

Throws:

java.io.FileNotFoundException - if the file is not found.

equals

public boolean equals(java.lang.Object other)

hashCode

public int hashCode()

list

public java.lang.String[] list()

Get the names of all files and sub-directories in the directory named by this path name.

Specified by:

list in interface StorageFile

Returns:

An array of the names of the files and directories in this directory denoted by this abstract pathname. The returned array will have length 0 if this directory is empty. Returns null if this StorageFile is not a directory, or if an I/O error occurs.

canWrite

public boolean canWrite()

Determine whether the named file is writable.

Specified by:

canWrite in interface StorageFile

Returns:

true if the file exists and is writable, false if not.

isDirectory

public boolean isDirectory()

Tests whether the named file is a directory, or not. This is only called in writable storage factories.

Specified by:

isDirectory in interface StorageFile

Returns:

true if named file exists and is a directory, false if not. The return value is undefined if the storage is read-only.

delete

public boolean delete()

Deletes the named file or empty directory. This method does not delete non-empty directories.

Specified by:

delete in interface StorageFile

Returns:

true if the named file or directory is successfully deleted, false if not

deleteAll

public boolean deleteAll()

Deletes the named file and, if it is a directory, all the files and directories it contains.

Specified by:

deleteAll in interface StorageFile

Returns:

true if the named file or directory is successfully deleted, false if not

getPath

public java.lang.String getPath()

Converts this StorageFile into a pathname string. The character returned by StorageFactory.getSeparator() is used to separate the directory and file names in the sequence.

The returned path may include the database directory. Therefore it cannot be directly used to make an StorageFile equivalent to this one.

Specified by:

getPath in interface StorageFile

Returns:

The pathname as a string.

See Also:

StorageFactory.getSeparator()

getCanonicalPath

public java.lang.String getCanonicalPath()
                                  throws java.io.IOException

Description copied from interface: StorageFile

Converts this StorageFile into a canonical pathname string. The form of the canonical path is system dependent.

Specified by:

getCanonicalPath in interface StorageFile

Returns:

The pathname as a string.

Throws:

java.io.IOException - if an I/O error occurred while finding the canonical name

getName

public java.lang.String getName()

Specified by:

getName in interface StorageFile

Returns:

The last segment in the path name, "" if the path name sequence is empty.

createNewFile

public boolean createNewFile()
                      throws java.io.IOException

If the named file does not already exist then create it as an empty normal file. The implementation must synchronize with other threads accessing the same file (in the same or a different process). If two threads both attempt to create a file with the same name at the same time then at most one should succeed.

Specified by:

createNewFile in interface StorageFile

Returns:

true if this thread's invocation of createNewFile successfully created the named file; false if not, i.e. false if the named file already exists or if another concurrent thread created it.

Throws:

java.io.IOException - - If the directory does not exist or some other I/O error occurred

renameTo

public boolean renameTo(StorageFile newName)

Rename the file denoted by this name. Note that StorageFile objects are immutable. This method renames the underlying file, it does not change this StorageFile object. The StorageFile object denotes the same name as before, however the exists() method will return false after the renameTo method executes successfully.

It is not specified whether this method will succeed if a file already exists under the new name.

Specified by:

renameTo in interface StorageFile

Parameters:

newName - the new name.

Returns:

true if the rename succeeded, false if not.

mkdir

public boolean mkdir()

Creates the named directory.

Specified by:

mkdir in interface StorageFile

Returns:

true if the directory was created; false if not.

mkdirs

public boolean mkdirs()

Creates the named directory, and all nonexistent parent directories.

Specified by:

mkdirs in interface StorageFile

Returns:

true if the directory was created, false if not

length

public long length()

Returns the length of the named file if it is not a directory. The return value is not specified if the file is a directory.

Specified by:

length in interface StorageFile

Returns:

The length, in bytes, of the named file if it exists and is not a directory, 0 if the file does not exist, or any value if the named file is a directory.

getParentDir

public StorageFile getParentDir()

Get the name of the parent directory if this name includes a parent.

Specified by:

getParentDir in interface StorageFile

Returns:

An StorageFile denoting the parent directory of this StorageFile, if it has a parent, null if it does not have a parent.

setReadOnly

public boolean setReadOnly()

Make the named file or directory read-only. This interface does not specify whether this also makes the file undeletable.

Specified by:

setReadOnly in interface StorageFile

Returns:

true if the named file or directory was made read-only, or it already was read-only; false if not.

getOutputStream

public java.io.OutputStream getOutputStream()
                                     throws java.io.FileNotFoundException

Creates an output stream from a file name. If a normal file already exists with this name it will first be truncated to zero length.

Specified by:

getOutputStream in interface StorageFile

Returns:

an output stream suitable for writing to the file.

Throws:

java.io.FileNotFoundException - if the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason.

getOutputStream

public java.io.OutputStream getOutputStream(boolean append)
                                     throws java.io.FileNotFoundException

Creates an output stream from a file name. If a normal file already exists with this name it will first be truncated to zero length.

Specified by:

getOutputStream in interface StorageFile

Parameters:

append - If true then data will be appended to the end of the file, if it already exists. If false and a normal file already exists with this name the file will first be truncated to zero length.

Returns:

an output stream suitable for writing to the file.

Throws:

java.io.FileNotFoundException - if the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason.

getExclusiveFileLock

public int getExclusiveFileLock()

Get an exclusive lock with this name. This is used to ensure that two or more JVMs do not open the same database at the same time.

Specified by:

getExclusiveFileLock in interface StorageFile

Returns:

EXCLUSIVE_FILE_LOCK_NOT_AVAILABLE if the lock cannot be acquired because it is already held.
EXCLUSIVE_FILE_LOCK if the lock was successfully acquired.
NO_FILE_LOCK_SUPPORT if the system does not support exclusive locks.

releaseExclusiveFileLock

public void releaseExclusiveFileLock()

Release the resource associated with an earlier acquired exclusive lock

Specified by:

releaseExclusiveFileLock in interface StorageFile

See Also:

InputStreamFile.getExclusiveFileLock()

getRandomAccessFile

public StorageRandomAccessFile getRandomAccessFile(java.lang.String mode)
                                            throws java.io.FileNotFoundException

Get a random access file.

Specified by:

getRandomAccessFile in interface StorageFile

Parameters:

mode - "r", "rw", "rws", or "rwd". The "rws" and "rwd" modes specify that the data is to be written to persistent store, consistent with the java.io.RandomAccessFile class ("synchronized" with the persistent storage, in the file system meaning of the word "synchronized"). However the implementation is not required to implement the "rws" or "rwd" modes. The implementation may treat "rws" and "rwd" as "rw". It is up to the user of this interface to call the StorageRandomAccessFile.sync method. However, if the "rws" or "rwd" modes are supported and the RandomAccessFile was opened in "rws" or "rwd" mode then the implementation of StorageRandomAccessFile.sync need not do anything.

Returns:

an object that can be used for random access to the file.

Throws:

java.lang.IllegalArgumentException - if the mode argument is not equal to one of "r", "rw", "rws", or "rwd".

java.io.FileNotFoundException - if the file exists but is a directory rather than a regular file, or cannot be opened or created for any other reason .

See Also:

java.io.RandomAccessFile

toString

public java.lang.String toString()

Get the file name for diagnostic purposes. Usually the same as getPath().

Specified by:

toString in interface StorageFile

Returns:

the file name