Simple threadsafe LevelDB-backed key-value store for Java

KeyValueStore.java

/**
 <dependency>
    <groupId>org.fusesource.leveldbjni</groupId>
    <artifactId>leveldbjni-all</artifactId>
    <version>1.7</version>
 </dependency>
*/

import com.google.common.base.Optional;
import org.iq80.leveldb.DB;
import org.iq80.leveldb.Options;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;

import static org.fusesource.leveldbjni.JniDBFactory.*;

public class KeyValueStore {
    private static final Logger logger = LoggerFactory.getLogger(KeyValueStore.class);
    private static DB db;

    public KeyValueStore(final String dbName) throws IOException {
        db = getDB(dbName);
        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                System.out.println("safely closing database...");
                safeClose(db);
            }
        });
    }

    public synchronized void put(String key, String val) throws IOException {
        db.put(bytes(key), bytes(val));
    }

    public synchronized Optional<String> get(String key) throws IOException {
        String val = asString(db.get(bytes(key)));
        return Optional.fromNullable(val);
    }

    private static DB getDB(final String dbName) {
        final Options options = new Options();
        options.createIfMissing(true);
        try {
            return factory.open(new File(dbName), options);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private static void safeClose(DB db) {
        if (db != null) try {
            db.close();
        } catch (IOException e) {
            logger.error("Exception caught:", e);
        }
    }

    public static void main(String[] args) throws IOException {
        final KeyValueStore exampledb = new KeyValueStore("exampledb");
        for (int i=0; i<10000; i++) {
            Optional<String> stringOptional = exampledb.get(String.valueOf(i));
            System.out.println(stringOptional);
        }
    }
}