Elasticsearch/ES教程（22）：RestClient实现多条件聚合过滤

Elasticsearch 是一个分布式可扩展的实时搜索和分析引擎,一个建立在全文搜索引擎 Apache Lucene(TM) 基础上的搜索引擎.当然 Elasticsearch 并不仅仅是 Lucene 那么简单，它不仅包括了全文搜索功能，还可以进行以下工作:

• 分布式实时文件存储，并将每一个字段都编入索引，使其可以被搜索。
• 实时分析的分布式搜索引擎。
• 可以扩展到上百台服务器，处理PB级别的结构化或非结构化数据。

本文主要讲解使用RestClient实现多条件聚合过滤
品牌：如家 速八 万豪 希尔顿等，聚合得出品牌列表，动态生成前端品牌筛选

package cn.bdbk.hotel.service.impl;

import cn.bdbk.hotel.mapper.HotelMapper;
import cn.bdbk.hotel.pojo.Hotel;
import cn.bdbk.hotel.pojo.HotelDoc;
import cn.bdbk.hotel.pojo.PageResult;
import cn.bdbk.hotel.pojo.RequestParams;
import cn.bdbk.hotel.service.IHotelService;
import com.alibaba.fastjson.JSON;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import lombok.extern.slf4j.Slf4j;
import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.geo.GeoPoint;
import org.elasticsearch.common.unit.DistanceUnit;
import org.elasticsearch.index.query.BoolQueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.index.query.functionscore.FunctionScoreQueryBuilder;
import org.elasticsearch.index.query.functionscore.ScoreFunctionBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.elasticsearch.search.aggregations.AggregationBuilders;
import org.elasticsearch.search.aggregations.Aggregations;
import org.elasticsearch.search.aggregations.bucket.terms.Terms;
import org.elasticsearch.search.fetch.subphase.highlight.HighlightField;
import org.elasticsearch.search.sort.SortBuilders;
import org.elasticsearch.search.sort.SortOrder;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

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

@Slf4j
@Service
public class HotelService extends ServiceImpl<HotelMapper, Hotel> implements IHotelService {

    @Autowired
    private RestHighLevelClient restHighLevelClient;

    @Override
    public Map<String, List<String>> filters(RequestParams params) {
        try {
            SearchRequest request = new SearchRequest("hotel");

            buildBasicQuery(params, request);
            //去掉文档
            request.source().size(0);
            //聚合,三要素 名称 类型 字段
            buildAggregation(request);
            SearchResponse response = restHighLevelClient.search(request, RequestOptions.DEFAULT);

            //返回结果
            Map<String, List<String>> result = new HashMap<>();
            //解析
            Aggregations aggregations = response.getAggregations();
            //根据名称获取聚合结果
            List<String> brandList = getAggByName(aggregations, "brandAgg");
            List<String> cityList = getAggByName(aggregations, "cityAgg");
            List<String> starNameList = getAggByName(aggregations, "brandAgg");
            result.put("品牌", brandList);
            result.put("城市", cityList);
            result.put("星级", starNameList);
            return result;
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private List<String> getAggByName(Aggregations aggregations, String aggName) {
        Terms brandTerms = aggregations.get(aggName);

        List<? extends Terms.Bucket> buckets = brandTerms.getBuckets();


        List<String> list = new ArrayList<>();
        for (Terms.Bucket bucket : buckets){
            String name = bucket.getKeyAsString();
            list.add(name);
        }
        return list;
    }

    private void buildAggregation(SearchRequest request) {
        request.source().aggregation(
                AggregationBuilders.terms("brandAgg")
                        .field("brand")
                        .size(100)
        );
        request.source().aggregation(
                AggregationBuilders.terms("cityAgg")
                        .field("city")
                        .size(100)
        );
        request.source().aggregation(
                AggregationBuilders.terms("starNameAgg")
                        .field("starName")
                        .size(100)
        );
    }

    private void buildBasicQuery(RequestParams params, SearchRequest request) {
        BoolQueryBuilder boolQuery = QueryBuilders.boolQuery();

        String key = params.getKey();
        //根据关键字查询
        if (key == null || "".equals(key)){
            boolQuery.must(QueryBuilders.matchAllQuery());
        }else {
            boolQuery.must(QueryBuilders.matchQuery("name", key));
        }

        //城市 品牌 星级 价格查询
        if (params.getCity() != null && !params.getCity().equals("")){
            boolQuery.filter(QueryBuilders.termQuery("city", params.getCity()));
        }

        if (params.getBrand() != null && !params.getBrand().equals("")){
            boolQuery.filter(QueryBuilders.termQuery("brand", params.getBrand()));
        }

        if (params.getStarName() != null && !params.getStarName().equals("")){
            boolQuery.filter(QueryBuilders.termQuery("starName", params.getStarName()));
        }

        if (params.getMinPrice() != null && params.getMaxPrice() != null){
            boolQuery.filter(QueryBuilders.rangeQuery("price").gte(params.getMinPrice()).lte(params.getMaxPrice()));
        }

        //算分控制
        FunctionScoreQueryBuilder functionScoreQueryBuilder = QueryBuilders.functionScoreQuery(
                //原始查询
                boolQuery,
                //function score数组
                new FunctionScoreQueryBuilder.FilterFunctionBuilder[]{
                        //其中的一个function score元素
                        new FunctionScoreQueryBuilder.FilterFunctionBuilder(
                                //过滤条件
                                QueryBuilders.termQuery("isAd", true),
                                //算分函数
                                ScoreFunctionBuilders.weightFactorFunction(10)
                        )
                }
        );

        request.source().query(boolQuery);
    }

    private PageResult handleResponse(SearchResponse response) {
        //解析响应
        SearchHits searchHits = response.getHits();
        //获取总条数
        long total = searchHits.getTotalHits().value;
        //获取文档数组
        SearchHit[] searchHit = searchHits.getHits();

        List<HotelDoc> hotels = new ArrayList<>();

        for (SearchHit hit : searchHit){
            //获取文档source
            String json = hit.getSourceAsString();
            //反序列化
            HotelDoc hotelDoc = JSON.parseObject(json, HotelDoc.class);
            //获取排序值
            Object[] sortValues = hit.getSortValues();
            if (sortValues.length > 0){
                Object sortValue = sortValues[0];
                hotelDoc.setDistance(sortValue);
            }
            hotels.add(hotelDoc);
        }


        return new PageResult(total, hotels);
    }
}