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Class org.w3c.tools.dbm.jdbm

java.lang.Object
   |
   +----org.w3c.tools.dbm.jdbm

public class jdbm

extends Object

BLOCK_SIZE

CACHE_SIZE

Default cache size.

DIR_BITS

Default directory bits for this database.

STORE_INSERT

Mode for store - Only insert this element if it is not already defined.

STORE_REPLACE

Mode for store - Replace any existing entry with the new provided one.

jdbm(File)

jdbm(String)

Opens a database file in the specified O_ mode.

allocateSpace(int)

Allocate space in the file.

delete(byte[])

Delete the association for the provided key.

delete(String)

Delete the association for the provided String key.

elements()

Enumerate the elements of the database.

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

getBytes(String)

getNextBucket(jdbmEnumerator)

Update this enumeration current bucket to the next one.

keys()

Enumerate the keys of this database.

loadBucket(int)

Load the bucket whose file pointer is given.

lookup(byte[])

Lookup the value associated with the provided key.

lookup(String)

Lookup the value associated to the given String key.

main(String[])

printAvail(PrintStream)

Print the list of available blocks:

printHeader(PrintStream)

Print various database options to the given stream.

reorganize(boolean)

Return a clean instance of that database, after reorganization.

save()

Save thisdatabase to disk.

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

Store the given association of key/value.

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.

trace(String)

unloadBucket()

Select a bucket to be removed from the cache, unload it.

write(jdbmBucket, byte[], byte[])

Allocate and write the provided key/value.

 public static final int STORE_REPLACE

Mode for store - Replace any existing entry with the new provided one.

 public static final int STORE_INSERT

Mode for store - Only insert this element if it is not already defined.

 protected static final int BLOCK_SIZE

 protected static final int DIR_BITS

Default directory bits for this database.

 protected static final int CACHE_SIZE

Default cache size.

 public jdbm(String filename) throws IOException

Opens a database file in the specified O_ mode.

Parameters:

filename - the database file name.

Throws: IOException

if a problem with the file occurs

 public jdbm(File file) throws IOException

 protected final void trace(String msg)

 public void printHeader(PrintStream out)

Print various database options to the given stream.

Parameters:

out - The PrintStream to display info to.

 public void printAvail(PrintStream out)

Print the list of available blocks:

Parameters:

out - The print stream to print to.

 protected int allocateSpace(int size)

Allocate space in the file.

Parameters:

size - The size of the file block we want.

Returns:

The file pointer to the allocated block.

 protected int write(jdbmBucket bucket,
                     byte key[],
                     byte data[]) throws IOException

Allocate and write the provided key/value. This is a short end for writing new associations to the file.

Parameters:

bucket - Suggested bucket to allocate data from.

key - The key part of the item to write.

data - The data part of the item to write.

Returns:

The file position of the written element.

 protected synchronized jdbmBucket unloadBucket() throws IOException

Select a bucket to be removed from the cache, unload it.

Returns:

A bucket ready to be reused.

 protected synchronized LRUEntry loadBucket(int fileptr) throws IOException

Load the bucket whose file pointer is given.

Parameters:

fileptr - The file pointer of the bucket to be loaded.

into - The bucket to resue (or null).

 public void store(byte key[],
                   byte value[],
                   int mode) throws IOException

Store the given association of key/value.

Parameters:

key - The bytes that makes the key.

value - The bytes that makes the value.

mode - The mode of the storing, can be...

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

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: IOException

for whatever

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

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: IOException

for whatever

 public byte[] lookup(byte key[]) throws IOException

Lookup the value associated with the provided key.

Parameters:

key - The bits of the key to look for.

Returns:

The bits that makes the associated value, or null if not found.

 public byte[] lookup(String key) throws IOException

Lookup the value associated to the given String key.

Parameters:

key - The string that we are looking for.

Returns:

The bits that makes the associated value, or null if not found.

 public byte[] fetch(byte key[]) throws IOException

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: IOException

for whatever

 public String fetch(String key) throws IOException

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: IOException

for whatever

 public byte[] fetchBytes(String key) throws IOException

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: IOException

for whatever

 public String fetchString(byte key[]) throws IOException

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: IOException

for whatever

 public boolean delete(byte key[]) throws IOException

Delete the association for the provided key.

Parameters:

key - The key of the element to remove.

Returns:

A boolean true if deletion was succesfull.

 public boolean delete(String key) throws IOException

Delete the association for the provided String key.

Parameters:

key - The key of the element to remove.

Returns:

A boolean true if deletion was succesfull.

 public void save() throws IOException

Save thisdatabase to disk.

 protected boolean getNextBucket(jdbmEnumerator enum) throws IOException

Update this enumeration current bucket to the next one.

Parameters:

enum - The current enumeration state.

Returns:

A boolean true if the end of the database has been reached, falseotherwise.

 public Enumeration keys()

Enumerate the keys of this database. This method will retun an enumeration object suitable to walk through all the keys of the database. You are not guaranteed that the enumerator will not enumerate the same key multiple time.

You are guaranteed, however that you will walk at least once through all the keys that were present at the time you created the enumeration (but not through the one that were deleted while you are walking through the database).

Returns:

An enumeration instance.

 public Enumeration elements()

Enumerate the elements of the database. This method has the same limitations then it's keys counterpart.

Returns:

An enumeration instance.

 public jdbm reorganize(boolean trace)

Return a clean instance of that database, after reorganization. Of course, no accesses should me made to the current database while cleaning it up. Note that this returns a new instance of the database !

Returns:

A clean database, or null if the reorganization failed.

 public static byte[] getBytes(String str)

 public static void main(String args[]) throws Exception

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