使用 java 连接 Elasticsearch

Question

I am new to java coming from python . I know there are lot of answers out there to connect ElasticSearch with java . But it is difficult for me to understand and some are outdated. In python, I can easily import elasticsearch module and connect to it.

Here's the Code in python:

from elasticsearch import Elasticsearch
es = Elasticsearch('localhost', port=9200, http_auth=('username', 'password'), scheme="http")

But in java , i have included the elasticsearch maven dependency in pom.xml . I want to connect to elasticsearch . I came to know RestHighLevelClient can do this job. I found this code. But don't know how to make it connect to Elastic Search.

public RestHighLevelClient createESRestClient() {
    CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
    credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(esUserName, esPassword));

    RestClientBuilder restClientBuilder = RestClient
            .builder(new HttpHost(esRestclientHost, 9200, "http"));
    // Use this one if your ElasticSearch server is setup to use username & password authentication
    if (esAuthentication) {
        restClientBuilder.setHttpClientConfigCallback(h -> h.setDefaultCredentialsProvider(credentialsProvider));
    }

    return new RestHighLevelClient(restClientBuilder);
}

Any one can help me or show me some sample code to connect with Elastic Search with java. In python, it was done in two lines. Help me with java .

Answer 1

For connecting elasticsearch using java you can use the below code:

public class ElasticsearchClient {
//private static final Logger log = LoggerFactory.getLogger(ElasticsearchClient.class);
private final RestHighLevelClient client;

public ElasticsearchClient(ElasticsearchConfig elasticsearchConfig) {
    client = new RestHighLevelClient(RestClient.builder(new HttpHost(elasticsearchConfig.getHost(),
            elasticsearchConfig.getPort(), "http")));
}
}

elasticsearchConfiguration:

host: localhost

port: 9200

• For more information you can see this and this .

You can even follow instructions from this documentation

You need to add this dependency in pom.xml

<dependency>
        <groupId>org.elasticsearch.client</groupId>
        <artifactId>elasticsearch-rest-high-level-client</artifactId>
        <version>${es.client.version}</version>
</dependency>

Update 1

Instead of separate config file, in order to add host and port inside code itself you can use below mentioned code:

public class ElasticsearchClient {
private static final Logger log = LoggerFactory.getLogger(ElasticsearchClient.class);
private final RestHighLevelClient client;


public ElasticsearchClient(ElasticsearchConfig elasticsearchConfig) {
    client = new RestHighLevelClient(RestClient.builder(new HttpHost("localhost", 9200, "http")));
}

Answer 2

For the current version Java REST Client version 7.5, follow the instructions at ElasticSearch Client :

RestHighLevelClient client = new RestHighLevelClient(
        RestClient.builder(
                new HttpHost("localhost", 9200, "http"),
                new HttpHost("localhost", 9201, "http")));

Maven repository , ElasticSearch Client :

<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-high-level-client</artifactId>
    <version>7.5.2</version>
</dependency>

All the API functions are specified at the client website: search, multi-search, index, etc.

The "Java Low Level REST Client" Basic Authentication is defined here :

final CredentialsProvider credentialsProvider =
    new BasicCredentialsProvider();
credentialsProvider.setCredentials(AuthScope.ANY,
    new UsernamePasswordCredentials("user", "password"));

RestClientBuilder builder = RestClient.builder(
    new HttpHost("localhost", 9200))
    .setHttpClientConfigCallback(new HttpClientConfigCallback() {
        @Override
        public HttpAsyncClientBuilder customizeHttpClient(
                HttpAsyncClientBuilder httpClientBuilder) {
            return httpClientBuilder
                .setDefaultCredentialsProvider(credentialsProvider);
        }
    });