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Class jdbm.Database

java.lang.Object
   |
   +----jdbm.Database

public class Database

extends Object

implements Serializable

Version:

$Revision: 1.4 $ $Date: 1998/05/22 19:52:52 $

Author:

Gunther Schadow

O_CREATE

Opens database file as a writer and creates a new database file if it does not already exist.

O_FAST

Opens database file in fast update mode.

O_NEWDB

Opens database file as a writer and creates a new database file regardless whether or not it already exists.

O_READER

Opens database file as a reader

O_WRITER

Opens database file as a writer

S_INSERT

Raises KeyExistsException if a data is attempted to be stored by a key that already exists.

S_REPLACE

Overwrites the data of a key if the key exists.

Database(File, int)

Opens a database file in the specified O_ mode.

Database(String, int)

Opens a database file in the specified O_ mode.

close()

Closes a data base

delete(byte[])

Deletes a key data pair from the database.

disableFastUpdateMode()

Disables the fast mode for updates.

enableFastUpdateMode()

Enables the fast mode for updates.

exists(byte[])

Checks whether the given key exists in the data base

exists(String)

Checks whether the given key exists in the data base

fetch(byte[])

Fetch the data if the given key exists in the data base

fetch(String)

Fetch the data if the given key exists in the data base

fetchBytes(String)

Fetch the data if the given key exists in the data base

fetchString(byte[])

Fetch the data if the given key exists in the data base

finalize()

firstkey()

For iteration: get first key in database.

nextkey(byte[])

For iteration: get next key in database following the given key.

reorganize()

Frees space in the data base after data has been deleted.

setCacheSize(int)

Sets the bucket cache size.

store(byte[], byte[], int)

Store the data for the given key in the specified S_ mode.

store(String, byte[], int)

Store the data for the given key in the specified S_ mode.

store(String, String, int)

Store the data for the given key in the specified S_ mode.

sync()

Synchronizes the data base on disk with recent updates in memory if database is in fast update mode.

 public static final int O_READER

Opens database file as a reader

 public static final int O_WRITER

Opens database file as a writer

 public static final int O_CREATE

Opens database file as a writer and creates a new database file if it does not already exist.

 public static final int O_NEWDB

Opens database file as a writer and creates a new database file regardless whether or not it already exists.

 public static final int O_FAST

Opens database file in fast update mode.

 public static final int S_INSERT

Raises KeyExistsException if a data is attempted to be stored by a key that already exists.

 public static final int S_REPLACE

Overwrites the data of a key if the key exists.

 public Database(File file,
                 int mode) throws IOException

Opens a database file in the specified O_ mode.

Parameters:

file - the database file.

mode - the O_ mode.

Throws: IOException

if a problem with the file occurs

 public Database(String filename,
                 int mode) throws IOException

Opens a database file in the specified O_ mode.

Parameters:

filename - the database file name.

mode - the O_ mode.

Throws: IOException

if a problem with the file occurs

 public native synchronized void close()

Closes a data base

 public native synchronized boolean exists(byte key[])

Checks whether the given key exists in the data base

Parameters:

key - the bytes of the key.

Returns:

true if key exists, false otherwise.

 public boolean exists(String key)

Checks whether the given key exists in the data base

Parameters:

key - the bytes of the key.

Returns:

true if key exists, false otherwise.

 public native synchronized byte[] fetch(byte key[]) throws NoSuchKeyException

Fetch the data if the given key exists in the data base

Parameters:

key - the bytes of the key.

Returns:

the data bytes stored for the key.

Throws: NoSuchKeyException

if key was not in data base.

 public String fetch(String key) throws NoSuchKeyException

Fetch the data if the given key exists in the data base

Parameters:

key - the bytes of the key.

Returns:

the data bytes stored for the key.

Throws: NoSuchKeyException

if key was not in data base.

 public byte[] fetchBytes(String key) throws NoSuchKeyException

Fetch the data if the given key exists in the data base

Parameters:

key - the bytes of the key.

Returns:

the data bytes stored for the key.

Throws: NoSuchKeyException

if key was not in data base.

 public String fetchString(byte key[]) throws NoSuchKeyException

Fetch the data if the given key exists in the data base

Parameters:

key - the bytes of the key.

Returns:

the data bytes stored for the key.

Throws: NoSuchKeyException

if key was not in data base.

 public native synchronized void store(byte key[],
                                       byte data[],
                                       int mode) throws KeyExistsException, IllegalOperationError

Store the data for the given key in the specified S_ mode.

Parameters:

key - the bytes of the key.

data - the bytes of the key.

mode - the S_ mode.

Returns:

the data bytes stored for the key.

Throws: KeyExistsException

if key is already in data base and an S_INSERT store has been attempted.

Throws: IllegalOperationError

if database is in read mode.

 public void store(String key,
                   byte data[],
                   int mode) throws KeyExistsException, IllegalOperationError

Store the data for the given key in the specified S_ mode.

Parameters:

key - the bytes of the key.

data - the bytes of the key.

mode - the S_ mode.

Returns:

the data bytes stored for the key.

Throws: KeyExistsException

if key is already in data base and an S_INSERT store has been attempted.

Throws: IllegalOperationError

if database is in read mode.

 public void store(String key,
                   String data,
                   int mode) throws KeyExistsException, IllegalOperationError

Store the data for the given key in the specified S_ mode.

Parameters:

key - the bytes of the key.

data - the bytes of the key.

mode - the S_ mode.

Returns:

the data bytes stored for the key.

Throws: KeyExistsException

if key is already in data base and an S_INSERT store has been attempted.

Throws: IllegalOperationError

if database is in read mode.

 public native synchronized void delete(byte key[]) throws IllegalOperationError

Deletes a key data pair from the database. No exception is raised if key does not exist. The purpose is that after calling this method the key will not exist, regardless of whether or not it existed before.

Parameters:

key - the bytes of the key.

Throws: IllegalOperationError

if database is in read mode.

 public native synchronized byte[] firstkey()

For iteration: get first key in database.

Returns:

the bytes of the first key or null if database is empty.

 public native synchronized byte[] nextkey(byte key[])

For iteration: get next key in database following the given key.

Returns:

the bytes of the next key or null if database is exhausted.

 public native synchronized void reorganize() throws IllegalOperationError

Frees space in the data base after data has been deleted.

Throws: IllegalOperationError

if database is in read mode.

 public native synchronized void sync()

Synchronizes the data base on disk with recent updates in memory if database is in fast update mode. Otherwise sync does nothing.

 public native synchronized void enableFastUpdateMode()

Enables the fast mode for updates.

 public native synchronized void disableFastUpdateMode()

Disables the fast mode for updates.

 public native synchronized void setCacheSize(int cachesize)

Sets the bucket cache size. This may only be done once.

Parameters:

cachesize - the cache size (default is 100).

Throws: IllegalOperationError

if cache size is set a second time.

 public void finalize()

Overrides:

finalize in class Object

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