给我写个ElasticsearchClient的工具类

好的，以下是一个简单的ElasticsearchClient工具类，你可以根据自己的需求进行修改和扩展：

import java.io.IOException;
import java.util.List;

import org.apache.http.HttpHost;
import org.elasticsearch.action.bulk.BulkRequest;
import org.elasticsearch.action.bulk.BulkResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.xcontent.XContentBuilder;
import org.elasticsearch.common.xcontent.XContentFactory;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.search.builder.SearchSourceBuilder;

public class ElasticsearchClientUtil {
    
    private static final String INDEX_NAME = "my_index";
    private static final String TYPE_NAME = "my_type";
    
    private RestHighLevelClient client;
    
    public ElasticsearchClientUtil(String host, int port) {
        client = new RestHighLevelClient(
                RestClient.builder(new HttpHost(host, port, "http")));
    }
    
    public void close() throws IOException {
        client.close();
    }
    
    public void indexDocument(String id, String jsonString) throws IOException {
        IndexRequest indexRequest = new IndexRequest(INDEX_NAME, TYPE_NAME, id)
                .source(jsonString, XContentType.JSON);
        client.index(indexRequest, RequestOptions.DEFAULT);
    }
    
    public void indexDocument(String id, XContentBuilder source) throws IOException {
        IndexRequest indexRequest = new IndexRequest(INDEX_NAME, TYPE_NAME, id).source(source);
        client.index(indexRequest, RequestOptions.DEFAULT);
    }
    
    public BulkResponse bulkIndexDocuments(List<IndexRequest> requests) throws IOException {
        BulkRequest bulkRequest = new BulkRequest();
        for (IndexRequest request : requests) {
            bulkRequest.add(request);
        }
        return client.bulk(bulkRequest, RequestOptions.DEFAULT);
    }
    
    public SearchResponse search(QueryBuilder queryBuilder, int from, int size) throws IOException {
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder()
                .query(queryBuilder)
                .from(from)
                .size(size);
        SearchRequest searchRequest = new SearchRequest(INDEX_NAME).source(sourceBuilder);
        return client.search(searchRequest, RequestOptions.DEFAULT);
    }
    
    public static void main(String[] args) throws IOException {
        ElasticsearchClientUtil clientUtil = new ElasticsearchClientUtil("localhost", 9200);
        String jsonString = "{\"name\": \"John Doe\", \"age\": 25}";
        XContentBuilder source = XContentFactory.jsonBuilder()
                .startObject()
                .field("name", "John Doe")
                .field("age", 25)
                .endObject();
        clientUtil.indexDocument("1", jsonString);
        clientUtil.indexDocument("2", source);
        clientUtil.close();
    }
}

这个工具类包含了一些基本的 Elasticsearch 操作，包括：

- 创建Elasticsearch客户端：使用给定的主机和端口创建RestHighLevelClient实例，这是与Elasticsearch进行交互的主要入口。
- 关闭Elasticsearch客户端：关闭RestHighLevelClient实例。
- 索引文档：将JSON字符串或XContentBuilder对象索引到指定的Elasticsearch索引和类型中。
- 批量索引文档：将多个索引请求打包成单个批量请求，并将其发送到Elasticsearch进行索引。
- 搜索文档：使用给定的QueryBuilder对象构建查询，然后使用SearchSourceBuilder构建搜索请求，最后使用RestHighLevelClient执行搜索请求并返回响应。

你可以根据自己的需求扩展这个工具类，添加更多的操作，例如删除文档、更新文档等等。