public static void main(String[] args) throws IOException {
// Open db in temp directory
File f = File.createTempFile("mapdb", "temp");
DB db = DBMaker.newFileDB(f).make();
// Open or create table
Map<String, Person> dbMap = db.getTreeMap("personAndCity");
// Add data
Person bilbo = new Person("Bilbo", "The Shire");
Person sauron = new Person("Sauron", "Mordor");
Person radagast = new Person("Radagast", "Crazy Farm");
dbMap.put("west", bilbo);
dbMap.put("south", sauron);
dbMap.put("mid", radagast);
// Commit and close
db.commit();
db.close();
//
// Second option for using cystom values is to use your own serializer.
// This usually leads to better performance as MapDB does not have to
// analyze the class structure.
//
class CustomSerializer implements ValueSerializer<Person>, Serializable {
@Override
public void serialize(DataOutput out, Person value) throws IOException {
out.writeUTF(value.getName());
out.writeUTF(value.getCity());
}
@Override
public Person deserialize(DataInput in, int available) throws IOException {
return new Person(in.readUTF(), in.readUTF());
}
@Override
public int fixedSize() {
return -1;
}
}
ValueSerializer<Person> serializer = new CustomSerializer();
DB db2 = DBMaker.newTempFileDB().make();
Map<String, Person> map2 = db2.createHashMap("map").valueSerializer(serializer).make();
map2.put("North", new Person("Yet another dwarf", "Somewhere"));
db2.commit();
db2.close();
}
@Override
public ConcurrentMap<String, String> getCacheMap(String namespaceKey) {
final Lock lock = nsLocks.get(namespaceKey);
lock.lock();
try {
String mapDBKey = currentNamespaceCache.get(namespaceKey);
if (mapDBKey == null) {
// Not something created by swapAndClearCache
mapDBKey = namespaceKey;
}
return mmapDB.createHashMap(mapDBKey).makeOrGet();
} finally {
lock.unlock();
}
}
@Override
public ConcurrentMap<String, String> getCacheMap(String namespaceOrCacheKey) {
final Lock lock = nsLocks.get(namespaceOrCacheKey);
lock.lock();
try {
String realKey = currentNamespaceCache.get(namespaceOrCacheKey);
if (realKey == null) {
realKey = namespaceOrCacheKey;
}
final Lock nsLock = nsLocks.get(realKey);
if (lock != nsLock) {
nsLock.lock();
}
try {
return mmapDB.createHashMap(realKey).makeOrGet();
} finally {
if (lock != nsLock) {
nsLock.unlock();
}
}
} finally {
lock.unlock();
}
}