前言

LevelDB 是一種Key-Value存儲數(shù)據(jù)庫
性能非常強悍 百度百科上介紹 可以支撐十億級
這段時間在研究區(qū)塊鏈的時候發(fā)現(xiàn)的這個數(shù)據(jù)庫

引入SDK

<dependency>
    <groupId>org.iq80.leveldb</groupId>
    <artifactId>leveldb-api</artifactId>
    <version>0.10</version>
</dependency>
<dependency>
    <groupId>org.iq80.leveldb</groupId>
    <artifactId>leveldb</artifactId>
    <version>0.10</version>
</dependency>

初始化DB

DBFactory factory = new Iq80DBFactory();
Options options = new Options();
options.createIfMissing(true);
//folder 是db存儲目錄
DB db = factory.open(new File(folder), options);

存儲Key Value 值

//levelDB 的api存儲都是字節(jié)數(shù)組  所以這里需要轉(zhuǎn)成字節(jié)數(shù)組
db.put(Iq80DBFactory.bytes(key), Iq80DBFactory.bytes(value));

獲取Value

byte[] bytes = db.get(Iq80DBFactory.bytes(key));
String value = Iq80DBFactory.asString(bytes);

刪除|更改

//刪除
db.delete(Iq80DBFactory.bytes(key));

//更改 重新put新的key - value即可
db.put(Iq80DBFactory.bytes(key), Iq80DBFactory.bytes(value));   

遍歷所有數(shù)據(jù)

public LinkedHashMap<String, String> iteratorDb() {
    DBIterator iterator = db.iterator();
    LinkedHashMap<String, String> linkedHashMap = new LinkedHashMap<>();
    while (iterator.hasNext()) {
        Map.Entry<byte[], byte[]> next = iterator.next();
        String key = Iq80DBFactory.asString(next.getKey());
        String value = Iq80DBFactory.asString(next.getValue());
        linkedHashMap.put(key, value);
    }
    return linkedHashMap;
}

測試插入一百萬條數(shù)據(jù)

基于SpringBoot搭建的控制器

隨機生成 指定數(shù)量的UUID 并且插入到LevelDB

從請求 到響應 5.5秒左右 如果再拋掉生成UUID的時間 可能更快 哈哈

@ResponseBody
@GetMapping("/generate")
public ResponeEntity generate(Long count) {
    DB db = levelDb.getDb();
    //創(chuàng)建批量處理
    WriteBatch batch = db.createWriteBatch();
    for (int i = 0; i < count; i++) {
        String uuid = UUID.randomUUID().toString();
        batch.put(Iq80DBFactory.bytes(uuid), Iq80DBFactory.bytes(uuid));
    }
    //執(zhí)行寫入
    db.write(batch);
    return buildRespone(null);
}

image

測試從一百萬數(shù)據(jù)中取出一條

PostMan 請求到響應時間 19毫秒

@ResponseBody
@GetMapping("/getLevel")
public ResponeEntity getLevel(String key) {
    byte[] bytes = db.get(Iq80DBFactory.bytes(key));
    String value = Iq80DBFactory.asString(bytes);
    return buildRespone(value);
}   

image