Elasticsearch工具类的封装

Elasticsearch是一个开源的分布式搜索引擎，它可以快速地存储、搜索和分析大量数据。在实际的使用中，我们通常需要对Elasticsearch进行一些封装，以简化API的使用。下面是一个Java工具类的封装示例：

import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.action.search.SearchType;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.builder.SearchSourceBuilder;

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

public class ElasticsearchUtil {

    private RestHighLevelClient restHighLevelClient;

    public ElasticsearchUtil(RestHighLevelClient restHighLevelClient) {
        this.restHighLevelClient = restHighLevelClient;
    }

    /**
     * 查询数据
     *
     * @param indexName 索引名称
     * @param typeName  类型名称
     * @param queryMap  查询条件
     * @param from      起始位置
     * @param size      返回数量
     * @return
     * @throws IOException
     */
    public List<Map<String, Object>> search(String indexName, String typeName, Map<String, Object> queryMap, int from, int size) throws IOException {
        SearchRequest searchRequest = new SearchRequest(indexName);
        searchRequest.types(typeName);
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        searchSourceBuilder.query(QueryBuilders.matchAllQuery());
        for (Map.Entry<String, Object> entry : queryMap.entrySet()) {
            searchSourceBuilder.query(QueryBuilders.matchQuery(entry.getKey(), entry.getValue()));
        }
        searchSourceBuilder.from(from);
        searchSourceBuilder.size(size);
        searchSourceBuilder.timeout(TimeValue.timeValueSeconds(60));
        searchRequest.source(searchSourceBuilder);
        searchRequest.searchType(SearchType.DFS_QUERY_THEN_FETCH);
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest);
        List<Map<String, Object>> resultList = new ArrayList<>();
        for (SearchHit searchHit : searchResponse.getHits()) {
            resultList.add(searchHit.getSourceAsMap());
        }
        return resultList;
    }

    //其他操作方法
}

这个工具类主要提供了查询数据的方法，支持基于多个属性的匹配查询，同时也可以设置从哪个位置开始返回、返回多少条数据等参数。在实际使用中，我们可以根据需求进一步封装其他操作，如新增、删除、更新等。