Java操作ElasticSearch

在Java中操作ElasticSearch，你可以使用ElasticSearch的Java Rest Client。以下是一个简单的例子，展示了如何使用Java Rest Client连接到ElasticSearch并执行基本的CRUD操作。

首先，确保你的项目中包含了ElasticSearch的Java Rest Client依赖。如果你使用Maven，可以添加如下依赖：

<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-high-level-client</artifactId>
    <version>7.10.0</version>
</dependency>

以下是一个简单的Java程序，演示了如何连接到ElasticSearch，创建索引，添加文档，搜索文档，更新文档，和删除文档。

import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.indices.CreateIndexRequest;
import org.elasticsearch.client.indices.GetIndexRequest;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.action.update.UpdateRequest;
import org.elasticsearch.action.delete.DeleteRequest;
import org.elasticsearch.action.delete.DeleteResponse;
import org.elasticsearch.search.builder.SearchSourceBuilder;
import org.elasticsearch.search.SearchHit;
 
public class ElasticSearchExample {
    public static void main(String[] args) throws IOException {
        // 初始化RestHighLevelClient
        try (RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http")))) {
 
            // 创建索引
            CreateIndexRequest createIndexRequest = new CreateIndexRequest("test_index");
            client.indices().create(createIndexRequest, RequestOptions.DEFAULT);
 
            // 添加文档
            IndexRequest indexRequest = new IndexRequest("test_index");
            indexRequest.id("1");
            indexRequest.source("field1", "value1");
            IndexResponse indexResponse = client.index(indexRequest, RequestOptions.DEFAULT);
 
            // 搜索文档
            SearchRequest searchRequest = new SearchRequest("test_index");
            SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
            searchSourceBuilder.query(QueryBuilders.matchQuery("field1", "value1"));
            searchRequest.source(searchSourceBuilder);
            SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
            SearchHit[] searchHits = searchResponse.getHits()