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如何在Java中使用Elasticsearch

news 来源：原创 2024/9/21 11:29:09

如何在Java中使用Elasticsearch

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概述

Elasticsearch 是一个开源的分布式搜索引擎，用于全文搜索、结构化搜索和分析。本文将介绍如何在Java应用程序中使用Elasticsearch，包括连接、索引文档、搜索以及一些最佳实践。

连接到Elasticsearch

要在Java中使用Elasticsearch，首先需要添加 Elasticsearch Java 客户端库的依赖。推荐使用官方提供的 High Level REST Client。

Gradle 依赖配置示例

dependencies {implementation 'org.elasticsearch.client:elasticsearch-rest-high-level-client:7.17.0'
}

Maven 依赖配置示例

<dependency><groupId>org.elasticsearch.client</groupId><artifactId>elasticsearch-rest-high-level-client</artifactId><version>7.17.0</version>
</dependency>

建立连接

使用 RestClient 建立与 Elasticsearch 的连接：

package cn.juwatech.elasticsearch;import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;public class ElasticsearchClient {private static final String ELASTICSEARCH_HOST = "localhost";private static final int ELASTICSEARCH_PORT = 9200;public RestHighLevelClient createClient() {return new RestHighLevelClient(RestClient.builder(new HttpHost(ELASTICSEARCH_HOST, ELASTICSEARCH_PORT, "http")));}public static void main(String[] args) {ElasticsearchClient client = new ElasticsearchClient();RestHighLevelClient restClient = client.createClient();// 使用 restClient 进行后续操作，如索引文档、搜索等}
}

索引文档

向 Elasticsearch 中索引文档：

import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.common.xcontent.XContentType;
import org.elasticsearch.index.Index;public class IndexDocumentExample {public void indexDocument(RestHighLevelClient client) throws IOException {IndexRequest request = new IndexRequest("posts");request.id("1");String jsonString = "{" +"\"user\":\"juwatech\"," +"\"postDate\":\"2024-07-01\"," +"\"message\":\"trying out Elasticsearch\"" +"}";request.source(jsonString, XContentType.JSON);IndexResponse indexResponse = client.index(request, RequestOptions.DEFAULT);System.out.println("Indexed document with ID: " + indexResponse.getId());}public static void main(String[] args) throws IOException {ElasticsearchClient client = new ElasticsearchClient();RestHighLevelClient restClient = client.createClient();IndexDocumentExample example = new IndexDocumentExample();example.indexDocument(restClient);restClient.close();}
}

搜索文档

从 Elasticsearch 中搜索文档：

import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.builder.SearchSourceBuilder;public class SearchDocumentExample {public void searchDocument(RestHighLevelClient client) throws IOException {SearchRequest searchRequest = new SearchRequest("posts");SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();sourceBuilder.query(QueryBuilders.termQuery("user", "juwatech"));searchRequest.source(sourceBuilder);SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);System.out.println("Search hits: " + searchResponse.getHits().getTotalHits().value);}public static void main(String[] args) throws IOException {ElasticsearchClient client = new ElasticsearchClient();RestHighLevelClient restClient = client.createClient();SearchDocumentExample example = new SearchDocumentExample();example.searchDocument(restClient);restClient.close();}
}