Tokyo Cabinet is a library of routines for managing a database. The database is a simple data file containing records, each is a pair of a key and a value. Every key and value is serial bytes with variable length. Both binary data and character string can be used as a key and a value. There is neither concept of data tables nor data types. Records are organized in hash table, B+ tree, or fixed-length array.
As for database of hash table, each key must be unique within a database, so it is impossible to store two or more records with a key overlaps. The following access methods are provided to the database: storing a record with a key and a value, deleting a record by a key, retrieving a record by a key. Moreover, traversal access to every key are provided, although the order is arbitrary. These access methods are similar to ones of DBM (or its followers: NDBM and GDBM) library defined in the UNIX standard. Tokyo Cabinet is an alternative for DBM because of its higher performance.
As for database of B+ tree, records whose keys are duplicated can be stored. Access methods of storing, deleting, and retrieving are provided as with the database of hash table. Records are stored in order by a comparison function assigned by a user. It is possible to access each record with the cursor in ascending or descending order. According to this mechanism, forward matching search for strings and range search for integers are realized.
As for database of fixed-length array, records are stored with unique natural numbers. It is impossible to store two or more records with a key overlaps. Moreover, the length of each record is limited by the specified length. Provided operations are the same as ones of hash database.
Install the latest version of Tokyo Cabinet beforehand and get the package of the Java binding of Tokyo Cabinet.
Enter the directory of the extracted package then perform installation.
./configure make make check su make install
When a series of work finishes, the JAR file `tokyocabinet.jar' and the shared object files `libjtokyocabinet.so' and so on are installed under `/usr/local/lib'.
Let the class search path include `/usr/local/lib/tokyocabinet.jar' and let the library search path include `/usr/local/lib'.
CLASSPATH="$CLASSPATH:/usr/local/lib/tokyocabinet.jar" LD_LIBRARY_PATH="$LD_LIBRARY_PATH:/usr/local/lib" export CLASSPATH LD_LIBRARY_PATH
The above settings can be specified by options of the runtime command.
java -cp tokyocabinet.jar -Djava.library.path=. FooBarBaz ...
All symbols of Tokyo Cabinet are defined in the package `tokyocabinet'. You can access them without any prefix by importing the package.
import tokyocabinet.*;
The following code is an example to use a hash database.
import tokyocabinet.*;
public class TCHDBEX {
public static void main(String[] args){
// create the object
HDB hdb = new HDB();
// open the database
if(!hdb.open("casket.hdb", HDB.OWRITER | HDB.OCREAT)){
int ecode = hdb.ecode();
System.err.println("open error: " + hdb.errmsg(ecode));
}
// store records
if(!hdb.put("foo", "hop") ||
!hdb.put("bar", "step") ||
!hdb.put("baz", "jump")){
int ecode = hdb.ecode();
System.err.println("put error: " + hdb.errmsg(ecode));
}
// retrieve records
String value = hdb.get("foo");
if(value != null){
System.out.println(value);
} else {
int ecode = hdb.ecode();
System.err.println("get error: " + hdb.errmsg(ecode));
}
// traverse records
hdb.iterinit();
String key;
while((key = hdb.iternext2()) != null){
value = hdb.get(key);
if(value != null){
System.out.println(key + ":" + value);
}
}
// close the database
if(!hdb.close()){
int ecode = hdb.ecode();
System.err.println("close error: " + hdb.errmsg(ecode));
}
}
}
The following code is an example to use a B+ tree database.
import tokyocabinet.*;
public class TCBDBEX {
public static void main(String[] args){
// create the object
BDB bdb = new BDB();
// open the database
if(!bdb.open("casket.bdb", BDB.OWRITER | BDB.OCREAT)){
int ecode = bdb.ecode();
System.err.println("open error: " + bdb.errmsg(ecode));
}
// store records
if(!bdb.put("foo", "hop") ||
!bdb.put("bar", "step") ||
!bdb.put("baz", "jump")){
int ecode = bdb.ecode();
System.err.println("put error: " + bdb.errmsg(ecode));
}
// retrieve records
String value = bdb.get("foo");
if(value != null){
System.out.println(value);
} else {
int ecode = bdb.ecode();
System.err.println("get error: " + bdb.errmsg(ecode));
}
// traverse records
BDBCUR cur = new BDBCUR(bdb);
cur.first();
String key;
while((key = cur.key2()) != null){
value = cur.val2();
if(value != null){
System.out.println(key + ":" + value);
}
cur.next();
}
// close the database
if(!bdb.close()){
int ecode = bdb.ecode();
System.err.println("close error: " + bdb.errmsg(ecode));
}
}
}
The following code is an example to use a B+ tree database.
import tokyocabinet.*;
public class TCFDBEX {
public static void main(String[] args){
// create the object
FDB fdb = new FDB();
// open the database
if(!fdb.open("casket.fdb", FDB.OWRITER | FDB.OCREAT)){
int ecode = fdb.ecode();
System.err.println("open error: " + fdb.errmsg(ecode));
}
// store records
if(!fdb.put("1", "one") ||
!fdb.put("12", "twelve") ||
!fdb.put("144", "one forty four")){
int ecode = fdb.ecode();
System.err.println("put error: " + fdb.errmsg(ecode));
}
// retrieve records
String value = fdb.get("1");
if(value != null){
System.out.println(value);
} else {
int ecode = fdb.ecode();
System.err.println("get error: " + fdb.errmsg(ecode));
}
// traverse records
fdb.iterinit();
String key;
while((key = fdb.iternext2()) != null){
value = fdb.get(key);
if(value != null){
System.out.println(key + ":" + value);
}
}
// close the database
if(!fdb.close()){
int ecode = fdb.ecode();
System.err.println("close error: " + fdb.errmsg(ecode));
}
}
}
The Java binding of Tokyo Cabinet is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License or any later version. The Java binding of Tokyo Cabinet is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the Java binding of Tokyo Cabinet; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.