Java RocksDB安装与应用-eolink官网

Java RocksDB安装与应用

rocksDB 是一个可嵌入的，持久性的 key-value存储。

以下介绍来自rocksDB 中文官网

https://rocksdb.org.cn/

它有以下四个特点

1 高性能：RocksDB使用一套日志结构的数据库引擎，为了更好的性能，这套引擎是用C++编写的。 Key和value是任意大小的字节流。

2 为快速存储而优化：RocksDB为快速而又低延迟的存储设备（例如闪存或者高速硬盘）而特殊优化处理。 RocksDB将最大限度的发挥闪存和RAM的高度率读写性能。

3 可适配性：RocksDB适合于多种不同工作量类型。从像MyRocks这样的数据存储引擎，到应用数据缓存, 甚至是一些嵌入式工作量，RocksDB都可以从容面对这些不同的数据工作量需求。

4 基础和高级的数据库操作 RocksDB提供了一些基础的操作，例如打开和关闭数据库。对于合并和压缩过滤等高级操作，也提供了读写支持。

RockDB 安装与使用

rocksDB 安装有多种方式。由于官方没有提供对应平台的二进制库，所以需要自己编译使用。

rocksDB 的安装很简单，但是需要转变一下对于rocksDB 的看法。它不是一个重量级别的数据库，是一个嵌入式的key-value 存储。这意味着你只要在你的Maven项目中添加 rocksDB的依赖，就可以在开发环境中自我尝试了。如果你没有理解这点，你就可能会走入下面这两种不推荐的安装方式。

方式一去查看rocksDB 的官网发现要写一个C++ 程序（不推荐）

#include

#include "rocksdb/db.h"

rocksdb::DB* db;

rocksdb::Options options;

options.create_if_missing = true;

rocksdb::Status status =

rocksdb::DB::Open(options, "/tmp/testdb", &db);

assert(status.ok());

创建一个数据库？？？？怎么和之前用的mysql 或者mongo 不一样，为啥没有一个start.sh 或者start.bat 之类的脚本。难道要我写。写完了编译发现还不知道怎么和rocksDB 库进行关联，怎么办，我C++都忘完了。

方式二使用pyrocksDB （不推荐）

http://pyrocksdb.readthedocs.io/en/latest/installation.html

详细的安装文档见pyrocksDB 的官网安装文档。

以上两种方式对于熟悉C++ 或者python 的开发者来说都比较友好，但对于java 开发者来说不是太友好。

接下来就介绍第三种方式。

方式AFWnsgkXf三使用maven （推荐）

新建maven 项目，修改pom.xml 依赖里面添加

org.rocksdb

rocksdbjni

5.8.6

可以选择你喜欢的版本。

然后更高maven 的语言级别，我这里全局设置为了1.8

jdk18

true

1.8

到这里，环境就装好了，是不是又回到了熟悉的java 世界。

然后copy 源码包下的一个类，在IDE中修改一下运行配置，加一个程序运行中数据库存储路径，就可以运行测试了。我会在文章最后给出这个类。

运行控制台会有日志输出，同时也文件中也会出现一下新的文件。

后面会更新更多关于rockDB 开发API 的介绍，以及在生产中的应用，希望大家关注。

// This source code is licensed under both the GPLv2 (found in the

// COPYING file in the root directory) and Apache 2.0 License

// (found in the LICENSE.Apache file in the root directory).

import org.rocksdb.*;

import org.rocksdb.util.SizeUnit;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import java.util.Map;

public class RocksDBSamplAFWnsgkXfe {

static {

RocksDB.loadLibrary();

}

public static void main(final String[] args) {

if (args.length < 1) {

System.out.println("usage: RocksDBSample db_path");

System.exit(-1);

}

final String db_path = args[0];

final String db_path_not_found = db_path + "_not_found";

System.out.println("RocksDBSample");

try (final Options options = new Options();

final Filter bloomFilter = new BloomFilter(10);

final ReadOptions readOptions = new ReadOptions()

.setFillCache(false);

final Statistics stats = new Statistics();

final RateLimiter rateLimiter = new RateLimiter(10000000,10000, 10)) {

try (final RocksDB db = RocksDB.open(options, db_path_not_found)) {

assert (false);

} catch (final RocksDBException e) {

System.out.format("Caught the expected exception -- %s\n", e);

}

try {

options.setCreateIfMissing(true)

.setStatistics(stats)

.setWriteBufferSize(8 * SizeUnit.KB)

.setMaxWriteBufferNumber(3)

.setMaxBackgroundCompactions(10)

.setCompressionType(CompressionType.SNAPPY_COMPRESSION)

.setCompactionStyle(CompactionStyle.UNIVERSAL);

} catch (final IllegalArgumentException e) {

assert (false);

}

assert (options.createIfMissing() == true);

assert (options.writeBufferSize() == 8 * SizeUnit.KB);

assert (options.maxWriteBufferNumber() == 3);

assert (options.maxBackgroundCompactions() == 10);

assert (options.compressionType() == CompressionType.SNAPPY_COMPRESSION);

assert (options.compactionStyle() == CompactionStyle.UNIVERSAL);

assert (options.memTableFactoryName().equals("SkipListFactory"));

options.setMemTableConfig(

new HashSkipListMemTableConfig()

.setHeight(4)

.setBranchingFactor(4)

.setBucketCount(2000000));

assert (options.memTableFactoryName().equals("HashSkipListRepFactory"));

options.setMemTableConfig(

new HashLinkedListMemTableConfig()

.setBucketCount(100000));

assert (options.memTableFactoryName().equals("HashLinkedListRepFactory"));

options.setMemTableConfig(

new VectorMemTableConfig().setReservedSize(10000));

assert (options.memTableFactoryName().equals("VectorRepFactory"));

options.setMemTableConfig(new SkipListMemTableConfig());

assert (options.memTableFactoryName().equals("SkipListFactory"));

options.setTableFormatConfig(new PlainTableConfig());

// Plain-Table requires mmap read

options.setAllowMmapReads(true);

assert (options.tableFactoryName().equals("PlainTable"));

options.setRateLimiter(rateLimiter);

final BlockBasedTableConfig table_options = new BlockBasedTableConfig();

table_options.setBlockCacheSize(64 * SizeUnit.KB)

.setFilter(bloomFilter)

.setCacheNumShardBits(6)

.setBlockSizeDeviation(5)

.setBlockRestartInterval(10)

.setCacheIndexAndFilterBlocks(true)

.setHashIndexAllowCollision(false)

.setBlockCacheCompressedSize(64 * SizeUnit.KB)

.setBlockCacheCompressedNumShardBits(10);

assert (table_options.blocAFWnsgkXfkCacheSize() == 64 * SizeUnit.KB);

assert (table_options.cacheNumShardBits() == 6);

assert (table_options.blockSizeDeviation() == 5);

assert (table_options.blockRestartInterval() == 10);

assert (table_options.cacheIndexAndFilterBlocks() == true);

assert (table_options.hashIndexAllowCollision() == false);

assert (table_options.blockCacheCompressedSize() == 64 * SizeUnit.KB);

assert (table_options.blockCacheCompressedNumShardBits() == 10);

options.setTableFormatConfig(table_options);

assert (options.tableFactoryName().equals("BlockBasedTable"));

try (final RocksDB db = RocksDB.open(options, db_path)) {

db.put("hello".getBytes(), "world".getBytes());

final byte[] value = db.get("hello".getBytes());

assert ("world".equals(new String(value)));

final String str = db.getProperty("rocksdb.stats");

assert (str != null && !str.equals(""));

} catch (final RocksDBException e) {

System.out.format("[ERROR] caught the unexpected exception -- %s\n", e);

assert (false);

}

try (final RocksDB db = RocksDB.open(options, db_path)) {

db.put("hello".getBytes(), "world".getBytes());

byte[] value = db.get("hello".getBytes());

System.out.format("Get('hello') = %s\n",

new String(value));

for (int i = 1; i <= 9; ++i) {

for (int j = 1; j <= 9; ++j) {

db.put(String.format("%dx%d", i, j).getBytes(),

String.format("%d", i * j).getBytes());

}

for (int i = 1; i <= 9; ++i) {

for (int j = 1; j <= 9; ++j) {

System.out.format("%s ", new String(db.get(

String.format("%dx%d", i, j).getBytes())));

}

System.out.println("");

}

// write batch test

try (final WriteOptions writeOpt = new WriteOptions()) {

for (int i = 10; i <= 19; ++i) {

try (final WriteBatch batch = new WriteBatch()) {

for (int j = 10; j <= 19; ++j) {

batch.put(String.format("%dx%d", i, j).getBytes(),

String.format("%d", i * j).getBytes());

}

db.write(writeOpt, batch);

}

for (int i = 10; i <= 19; ++i) {

for (int j = 10; j <= 19; ++j) {

assert (new String(

db.get(String.format("%dx%d", i, j).getBytes())).equals(

String.format("%d", i * j)));

System.out.format("%s ", new String(db.get(

String.format("%dx%d", i, j).getBytes())));

}

System.out.println("");

}

value = db.get("1x1".getBytes());

assert (value != null);

value = db.get("world".getBytes());

assert (value == null);

value = db.get(readOptions, "world".getBytes());

assert (value == null);

final byte[] testKey = "asdf".getBytes();

final byte[] testValue =

"asdfghjkl;'?>

db.put(testKey, testValue);

byte[] testResult = db.get(testKey);

assert (testResult != null);

assert (Arrays.equals(testValue, testResult));

assert (new String(testValue).equals(new String(testResult)));

testResult = db.get(readOptions, testKey);

assert (testResult != null);

assert (Arrays.equals(testValue, testResult));

assert (new String(testValue).equals(new String(testResult)));

final byte[] insufficientArray = new byte[10];

final byte[] enoughArray = new byte[50];

int len;

len = db.get(testKey, insufficientArray);

assert (len > insufficientArray.length);

len = db.get("asdfjkl;".getBytes(), enoughArray);

assert (len == RocksDB.NOT_FOUND);

len = db.get(testKey, enoughArray);

assert (len == testValue.length);

len = db.get(readOptions, testKey, insufficientArray);

assert (len > insufficientArray.length);

len = db.get(readOptions, "asdfjkl;".getBytes(), enoughArray);

assert (len == RocksDB.NOT_FOUND);

len = db.get(readOptions, testKey, enoughArray);

assert (len == testValue.length);

db.remove(testKey);

len = db.get(testKey, enoughArray);

assert (len == RocksDB.NOT_FOUND);

// repeat the test with WriteOptions

try (final WriteOptions writeOpts = new WriteOptions()) {

writeOpts.setSync(true);

writeOpts.setDisableWAL(true);

db.put(writeOpts, testKey, testValue);

len = db.get(testKey, enoughArray);

assert (len == testValue.length);

assert (new String(testValue).equals(

new String(enoughArray, 0, len)));

}

try {

for (final TickerType statsType : TickerType.values()) {

if (statsType != TickerType.TICKER_ENUM_MAX) {

stats.getTickerCount(statsType);

}

System.out.println("getTickerCount() passed.");

} catch (final Exception e) {

System.out.println("Failed in call to getTickerCount()");

assert (false); //Should never reach here.

}

try {

for (final HistogramType histogramType : HistogramType.values()) {

if (histogramType != HistogramType.HISTOGRAM_ENUM_MAX) {

HistogramData data = stats.getHistogramData(histogramType);

}

System.out.println("getHistogramData() passed.");

} catch (final Exception e) {

System.out.println("Failed in call to getHistogramData()");

assert (false); //Should never reach here.

}

try (final RocksIterator iterator = db.newIterator()) {

boolean seekToFirstPassed = false;

for (iterator.seekToFirst(); iterator.isValid(); iterator.next()) {

iterator.status();

assert (iterator.key() != null);

assert (iterator.value() != null);

seekToFirstPassed = true;

}

if (seekToFirstPassed) {

System.out.println("iterator seekToFirst tests passed.");

}

boolean seekToLastPassed = false;

for (iterator.seekToLast(); iterator.isValid(); iterator.prev()) {

iterator.status();

assert (iterator.key() != null);

assert (iterator.value() != null);

seekToLastPassed = true;

}

if (seekToLastPassed) {

System.out.println("iterator seekToLastPassed tests passed.");

}

iterator.seekToFirst();

iterator.seek(iterator.key());

assert (iterator.key() != null);

assert (iterator.value() != null);

System.out.println("iterator seek test passed.");

}

System.out.println("iterator tests passed.");

final List keys = new ArrayList<>();

try (final RocksIterator iterator = db.newIterator()) {

for (iterator.seekToLast(); iterator.isValid(); iterator.prev()) {

keys.add(iterator.key());

}

Map values = db.multiGet(keys);

assert (values.size() == keys.size());

for (final byte[] value1 : values.values()) {

assert (value1 != null);

}

values = db.multiGet(new ReadOptions(), keys);

assert (values.size() == keys.size());

for (final byte[] value1 : values.values()) {

assert (value1 != null);

}

} catch (final RocksDBException e) {

System.err.println(e);

}

以上就是本次给大家介绍的Java中RocksDB安装与应用的全部内容，如果大家在学习后还有任何不明白的可以在下方的留言区域讨论，感谢对我们的支持。

db.put(testKey, testValue);

byte[] testResult = db.get(testKey);

assert (testResult != null);

assert (Arrays.equals(testValue, testResult));

assert (new String(testValue).equals(new String(testResult)));

testResult = db.get(readOptions, testKey);

assert (testResult != null);

assert (Arrays.equals(testValue, testResult));

assert (new String(testValue).equals(new String(testResult)));

final byte[] insufficientArray = new byte[10];

final byte[] enoughArray = new byte[50];

int len;

len = db.get(testKey, insufficientArray);

assert (len > insufficientArray.length);

len = db.get("asdfjkl;".getBytes(), enoughArray);

assert (len == RocksDB.NOT_FOUND);

len = db.get(testKey, enoughArray);

assert (len == testValue.length);

len = db.get(readOptions, testKey, insufficientArray);

assert (len > insufficientArray.length);

len = db.get(readOptions, "asdfjkl;".getBytes(), enoughArray);

assert (len == RocksDB.NOT_FOUND);

len = db.get(readOptions, testKey, enoughArray);

assert (len == testValue.length);

db.remove(testKey);

len = db.get(testKey, enoughArray);

assert (len == RocksDB.NOT_FOUND);

// repeat the test with WriteOptions

try (final WriteOptions writeOpts = new WriteOptions()) {

writeOpts.setSync(true);

writeOpts.setDisableWAL(true);

db.put(writeOpts, testKey, testValue);

len = db.get(testKey, enoughArray);

assert (len == testValue.length);

assert (new String(testValue).equals(

new String(enoughArray, 0, len)));

}

try {

for (final TickerType statsType : TickerType.values()) {

if (statsType != TickerType.TICKER_ENUM_MAX) {

stats.getTickerCount(statsType);

}

System.out.println("getTickerCount() passed.");

} catch (final Exception e) {

System.out.println("Failed in call to getTickerCount()");

assert (false); //Should never reach here.

}

try {

for (final HistogramType histogramType : HistogramType.values()) {

if (histogramType != HistogramType.HISTOGRAM_ENUM_MAX) {

HistogramData data = stats.getHistogramData(histogramType);

}

System.out.println("getHistogramData() passed.");

} catch (final Exception e) {

System.out.println("Failed in call to getHistogramData()");

assert (false); //Should never reach here.

}

try (final RocksIterator iterator = db.newIterator()) {

boolean seekToFirstPassed = false;

for (iterator.seekToFirst(); iterator.isValid(); iterator.next()) {

iterator.status();

assert (iterator.key() != null);

assert (iterator.value() != null);

seekToFirstPassed = true;

}

if (seekToFirstPassed) {

System.out.println("iterator seekToFirst tests passed.");

}

boolean seekToLastPassed = false;

for (iterator.seekToLast(); iterator.isValid(); iterator.prev()) {

iterator.status();

assert (iterator.key() != null);

assert (iterator.value() != null);

seekToLastPassed = true;

}

if (seekToLastPassed) {

System.out.println("iterator seekToLastPassed tests passed.");

}

iterator.seekToFirst();

iterator.seek(iterator.key());

assert (iterator.key() != null);

assert (iterator.value() != null);

System.out.println("iterator seek test passed.");

}

System.out.println("iterator tests passed.");

final List keys = new ArrayList<>();

try (final RocksIterator iterator = db.newIterator()) {

for (iterator.seekToLast(); iterator.isValid(); iterator.prev()) {

keys.add(iterator.key());

}

Map values = db.multiGet(keys);

assert (values.size() == keys.size());

for (final byte[] value1 : values.values()) {

assert (value1 != null);

}

values = db.multiGet(new ReadOptions(), keys);

assert (values.size() == keys.size());

for (final byte[] value1 : values.values()) {

assert (value1 != null);

}

} catch (final RocksDBException e) {

System.err.println(e);

}

以上就是本次给大家介绍的Java中RocksDB安装与应用的全部内容，如果大家在学习后还有任何不明白的可以在下方的留言区域讨论，感谢对我们的支持。

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