LevelDB JNI gives you a Java interface to the LevelDB C++ library which is a fast key-value storage library written at Google that provides an ordered mapping from string keys to string values.
This LevelDB JNI is based on leveldb-1.23 and snappy-1.1.9 .
Maybe you need this LevelDB JNI ?
NOTE: If you are using org.fusesource.leveldbjni/leveldbjni-all/1.8 Here's what you need to know this jni:
suspendCompactionsandresumeCompactionsare no longer supported.- 1.23.1 +, iterator.prev() changed, see change
Just add the following jar to your java project: leveldbjni-all-1.23.1.jar
dependencies {
implementation 'com.halibobor:leveldbjni-all:1.23.1'
} <dependency>
<groupId>com.halibobor</groupId>
<artifactId>leveldbjni-all</artifactId>
<version>1.23.1</version>
</dependency>
Recommended Package imports:
import org.iq80.leveldb.*;
import static org.fusesource.leveldbjni.JniDBFactory.*;
import java.io.*;Opening and closing the database.
Options options = new Options();
options.createIfMissing(true);
DB db = factory.open(new File("example"), options);
try {
// Use the db in here....
} finally {
// Make sure you close the db to shutdown the
// database and avoid resource leaks.
db.close();
}Putting, Getting, and Deleting key/values.
db.put(bytes("Tampa"), bytes("rocks"));
String value = asString(db.get(bytes("Tampa")));
db.delete(bytes("Tampa"));Performing Batch/Bulk/Atomic Updates.
WriteBatch batch = db.createWriteBatch();
try {
batch.delete(bytes("Denver"));
batch.put(bytes("Tampa"), bytes("green"));
batch.put(bytes("London"), bytes("red"));
db.write(batch);
} finally {
// Make sure you close the batch to avoid resource leaks.
batch.close();
}Iterating key/values.
DBIterator iterator = db.iterator();
try {
for(iterator.seekToFirst(); iterator.Valid(); iterator.next()) {
String key = asString(iterator.key());
String value = asString(iterator.value());
System.out.println(key+" = "+value);
}
} finally {
// Make sure you close the iterator to avoid resource leaks.
iterator.close();
}
try {
for(iterator.seekToLast(); iterator.Valid(); iterator.prev()) {
String key = asString(iterator.key());
String value = asString(iterator.value());
System.out.println(key+" = "+value);
}
} finally {
// Make sure you close the iterator to avoid resource leaks.
iterator.close();
}Working against a Snapshot view of the Database.
ReadOptions ro = new ReadOptions();
ro.snapshot(db.getSnapshot());
try {
// All read operations will now use the same
// consistent view of the data.
... = db.iterator(ro);
... = db.get(bytes("Tampa"), ro);
} finally {
// Make sure you close the snapshot to avoid resource leaks.
ro.snapshot().close();
}Using a custom Comparator.
DBComparator comparator = new DBComparator(){
public int compare(byte[] key1, byte[] key2) {
return new String(key1).compareTo(new String(key2));
}
public String name() {
return "simple";
}
public byte[] findShortestSeparator(byte[] start, byte[] limit) {
return start;
}
public byte[] findShortSuccessor(byte[] key) {
return key;
}
};
Options options = new Options();
options.comparator(comparator);
DB db = factory.open(new File("example"), options); Disabling Compression.
Options options = new Options();
options.compressionType(CompressionType.NONE);
DB db = factory.open(new File("example"), options);Configuring the Cache.
Options options = new Options();
options.cacheSize(100 * 1048576); // 100MB cache
DB db = factory.open(new File("example"), options);Configuring the BloomFilter.
Options options = new Options();
options.bitsPerKey(10);
DB db = factory.open(new File("example"), options);Getting approximate sizes.
long[] sizes = db.getApproximateSizes(new Range(bytes("a"), bytes("k")), new Range(bytes("k"), bytes("z")));
System.out.println("Size: "+sizes[0]+", "+sizes[1]);Getting database status.
String stats = db.getProperty("leveldb.stats");
System.out.println(stats);Getting database approximate-memory-usage.
String approximate = db.getProperty("leveldb.approximate-memory-usage");
System.out.println(approximate);Getting informational log messages.
Logger logger = new Logger() {
public void log(String message) {
System.out.println(message);
}
};
Options options = new Options();
options.logger(logger);
DB db = factory.open(new File("example"), options);Destroying a database.
Options options = new Options();
factory.destroy(new File("example"), options);Repairing a database.
Options options = new Options();
factory.repair(new File("example"), options);Using a memory pool to make native memory allocations more efficient:
JniDBFactory.pushMemoryPool(1024 * 512);
try {
// .. work with the DB in here,
} finally {
JniDBFactory.popMemoryPool();
}The following Steps work on mac, linux well, other platforms are not verified yet.
Welcome to contribute to other platforms.
The following worked for me on:
- OS X Mojave with X Code 11 (x86_64)
- OS X Monterey with X Code 13 (aarch64)
- CentOS (x86_64 | i386 | aarch64)
- GNU compiler toolchain,gcc-c++
- openssl, openssl-devel(cmake required)
- JAVA(1.8+)，make sure the current session $JAVA_HOME is set.
- cmake3.1+
- git
- maven3
- automake
- autoconf
- pkg-configls,build-essential,libtool (linux maybe required)
Then download the snappy, leveldb, leveldbjni,leveldbjni-all project source code.
git clone https://github.com/halibobor/leveldbjni-all.git
cd leveldbjni-all
git submodule update --init --recursive
cd third_party cd snappy
mkdir build && cd build
cmake -DCMAKE_BUILD_TYPE=Release ../
make && make DESTDIR=/tmp install
cd ../../ cd leveldb
export LIBRARY_PATH=/tmp/usr/local/lib
# export LIBRARY_PATH=/tmp/usr/local/lib64
export CPLUS_INCLUDE_PATH=/tmp/usr/local/include
mkdir build && cd build
cmake -DCMAKE_BUILD_TYPE=Release .. && cmake --build .
./db_test
./db_bench
make DESTDIR=/tmp install
cd ../../ cd leveldbjni
export SNAPPY_HOME=/tmp/usr/local
export LEVELDB_HOME=/tmp/usr/local
mvn clean package -P ${platform}Replace ${platform} with one of the following platform identifiers (depending on the platform your building on):
- osx
- linux32
- linux64
- linux64-aarch64
- linux64-ppc64le
- linux64-sunos64-amd64
- linux64-sunos64-sparcv9
- win32
- win64
- freebsd64
leveldbjni-${platform}/target/native-build/target/lib/leveldbjni-${version}.[jnilib|so|dll]: native library using your currently platform.leveldbjni/target/leveldbjni-${version}-native-src.zip: A GNU style source project which you can use to build the native library on other systems.leveldbjni-${platform}/target/leveldbjni-${platform}-${version}.jar: A jar file containing the built native library using your currently platform.
git clone https://github.com/halibobor/leveldbjni-all.git
cd leveldbjni-all
cd src/main/resources/META-INF/
# mkdir for native library
mkdir -p ${os}${bit-model}/${arch}
# cp native library to ${os}${bit-model}/${arch}
cp ${native_library_path}/leveldbjni-1.23.jnilib ${os}${bit-model}/${arch}
# update pom.xml
# add new config to Bundle-NativeCode
# such as META-INF/native/osx64/aarch64/libleveldbjni.jnilib;osname=macosx;processor=aarch64
mvn clean install${os},${bit-model},${arch} values, such as osx,64,x86_64.
${platform}=${os}${bit-model},such as osx64.
Please refer to Library.java to get more.
leveldbjni/target/leveldbjni-all-${version}.jar: The java class file to the library.