在 Elasticsearch 7.17 中，RestHighLevelClient 已经被宣布为过时，请使用ElasticsearchClient,写个操作ES的工具类

好的，下面是一个操作 Elasticsearch 的工具类：

import org.apache.http.HttpHost;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.DocWriteResponse;
import org.elasticsearch.action.delete.DeleteRequest;
import org.elasticsearch.action.delete.DeleteResponse;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
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.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.client.indices.CreateIndexRequest;
import org.elasticsearch.client.indices.CreateIndexResponse;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.xcontent.XContentType;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.builder.SearchSourceBuilder;

import java.io.IOException;
import java.util.Map;

public class EsUtil {

    private static RestHighLevelClient client;

    static {
        RestClientBuilder builder = RestClient.builder(
                new HttpHost("localhost", 9200, "http")
        );
        client = new RestHighLevelClient(builder);
    }

    /**
     * 创建索引
     *
     * @param indexName 索引名称
     * @param settings  索引配置
     * @param mappings  索引映射
     * @return 是否创建成功
     */
    public static boolean createIndex(String indexName, Settings settings, String mappings) {
        try {
            CreateIndexRequest request = new CreateIndexRequest(indexName);
            request.settings(settings);
            request.mapping(mappings, XContentType.JSON);
            CreateIndexResponse response = client.indices().create(request);
            return response.isAcknowledged();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
    }

    /**
     * 判断索引是否存在
     *
     * @param indexName 索引名称
     * @return 是否存在
     */
    public static boolean existsIndex(String indexName) {
        try {
            return client.indices().exists(new GetIndexRequest(indexName), RequestOptions.DEFAULT);
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
    }

    /**
     * 删除索引
     *
     * @param indexName 索引名称
     * @return 是否删除成功
     */
    public static boolean deleteIndex(String indexName) {
        try {
            AcknowledgedResponse response = client.indices().delete(new DeleteIndexRequest(indexName), RequestOptions.DEFAULT);
            return response.isAcknowledged();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
    }

    /**
     * 新增文档
     *
     * @param indexName 索引名称
     * @param id        文档id
     * @param source    文档内容
     * @return 是否新增成功
     */
    public static boolean indexDocument(String indexName, String id, Map<String, Object> source) {
        try {
            IndexRequest request = new IndexRequest(indexName);
            request.id(id);
            request.source(source);
            IndexResponse response = client.index(request, RequestOptions.DEFAULT);
            return response.getResult() == DocWriteResponse.Result.CREATED || response.getResult() == DocWriteResponse.Result.UPDATED;
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
    }

    /**
     * 删除文档
     *
     * @param indexName 索引名称
     * @param id        文档id
     * @return 是否删除成功
     */
    public static boolean deleteDocument(String indexName, String id) {
        try {
            DeleteRequest request = new DeleteRequest(indexName, id);
            DeleteResponse response = client.delete(request, RequestOptions.DEFAULT);
            return response.getResult() == DocWriteResponse.Result.DELETED;
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
    }

    /**
     * 获取文档
     *
     * @param indexName 索引名称
     * @param id        文档id
     * @return 文档内容
     */
    public static Map<String, Object> getDocument(String indexName, String id) {
        try {
            GetRequest request = new GetRequest(indexName, id);
            GetResponse response = client.get(request, RequestOptions.DEFAULT);
            if (response.isExists()) {
                return response.getSourceAsMap();
            } else {
                return null;
            }
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 搜索文档
     *
     * @param indexName 索引名称
     * @param query     查询条件
     * @param size      返回数量
     * @return 搜索结果
     */
    public static SearchHit[] search(String indexName, String query, int size) {
        try {
            SearchRequest request = new SearchRequest(indexName);
            SearchSourceBuilder builder = new SearchSourceBuilder();
            builder.query(QueryBuilders.queryStringQuery(query));
            builder.size(size);
            request.source(builder);
            SearchResponse response = client.search(request, RequestOptions.DEFAULT);
            if (response.status() == RestStatus.OK) {
                return response.getHits().getHits();
            } else {
                return new SearchHit[0];
            }
        } catch (IOException e) {
            e.printStackTrace();
            return new SearchHit[0];
        }
    }

    /**
     * 异步搜索文档
     *
     * @param indexName 索引名称
     * @param query     查询条件
     * @param size      返回数量
     * @param listener  异步回调
     */
    public static void searchAsync(String indexName, String query, int size, ActionListener<SearchResponse> listener) {
        SearchRequest request = new SearchRequest(indexName);
        SearchSourceBuilder builder = new SearchSourceBuilder();
        builder.query(QueryBuilders.queryStringQuery(query));
        builder.size(size);
        request.source(builder);
        client.searchAsync(request, RequestOptions.DEFAULT, listener);
    }

    /**
     * 关闭客户端连接
     */
    public static void close() {
        try {
            client.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

这个工具类提供了创建索引、删除索引、新增文档、删除文档、获取文档、搜索文档等基本操作。其中，`RestHighLevelClient` 用于操作 Elasticsearch，`RestClientBuilder` 用于创建 `RestHighLevelClient` 实例，`HttpHost` 表示 Elasticsearch 的主机和端口，可以根据实际情况修改。