es8 java api

### Elasticsearch 8 Java API Usage and Documentation Elasticsearch 8 provides an extensive range of APIs that allow developers to interact with the search engine using various programming languages, including Java. The official documentation is available on the Elastic website[^6]. Below are some key points regarding the usage of Elasticsearch 8's Java API: #### Setting Up the Connection To connect to an Elasticsearch cluster from a Java application, you should use the **High-Level REST Client (HLRC)** provided by Elasticsearch. This client simplifies interactions such as indexing documents, searching data, updating records, etc. Here’s how one might configure it: ```java import org.elasticsearch.client.RestHighLevelClient; import org.apache.http.HttpHost; RestHighLevelClient client = new RestHighLevelClient( RestClient.builder( HttpHost.create("http://localhost:9200") ) ); ``` The `RestHighLevelClient` requires specifying the host where your Elasticsearch instance resides along with its port number[^7]. #### Indexing Documents Indexing involves adding or updating a document within an index. Here's an example demonstrating this process: ```java import org.elasticsearch.action.index.IndexRequest; import org.elasticsearch.action.index.IndexResponse; import org.elasticsearch.common.xcontent.XContentType; String jsonString = "{" + "\"user\":\"kimchy\"," + "\"postDate\":\"2013-01-30\"," + "\"message\":\"trying out Elasticsearch\"" + "}"; IndexRequest request = new IndexRequest("posts"); request.source(jsonString, XContentType.JSON); IndexResponse response = client.index(request, RequestOptions.DEFAULT); System.out.println(response.getId()); ``` This snippet shows creating a JSON object representing a blog post being indexed into the `"posts"` index[^8]. #### Searching Data Searching retrieves matching results based on specified criteria. A basic query could look like so: ```java import org.elasticsearch.action.search.SearchRequest; import org.elasticsearch.action.search.SearchResponse; import org.elasticsearch.index.query.QueryBuilders; import org.elasticsearch.search.builder.SearchSourceBuilder; SearchRequest searchRequest = new SearchRequest("posts"); SearchSourceBuilder sourceBuilder = new SearchSourceBuilder(); sourceBuilder.query(QueryBuilders.matchQuery("user", "kimchy")); searchRequest.source(sourceBuilder); SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT); // Process 'searchResponse' here... ``` In this case, we're performing a match query against all entries under the user field equaling “kimchy”. Results would then be processed accordingly[^9]. #### Updating Records Updates modify existing fields without replacing entire documents. ```java import org.elasticsearch.action.update.UpdateRequest; import org.elasticsearch.action.update.UpdateResponse; UpdateRequest updateRequest = new UpdateRequest("posts", "document_id"); updateRequest.doc "{\"views\": 42}", XContentType.JSON ); UpdateResponse updateResponse = client.update(updateRequest, RequestOptions.DEFAULT); ``` Replace `"document_id"` appropriately when applying updates[^10]. #### Closing Resources Properly Always ensure resources get released after operations conclude: ```java client.close(); ``` For more advanced functionalities beyond these examples—such as aggregations, bulk processing, scroll support—you may refer directly to the comprehensive guide hosted online at https://www.elastic.co/guide/en/elasticsearch/client/java-api-client/current/index.html[^11].