数据聚合
聚合的种类
DSL实现Bucket聚合
如图所示，设置了10个桶，那么就显示了数量最多的前10个桶，品牌含有7天酒店的有30家，
品牌含有如家的也有30家。
修改排序规则
限定聚合范围
DSL实现Metrics聚合
如下案例要求对不同的品牌进行统计，所以要进行分组。
如图所示，要对桶的平均评分做排序，要使用不同桶的平均评分
RestClient实现聚合
请求组装
@Testvoid testAggregation() throws IOException {//1.准备RequestSearchRequest request = new SearchRequest("hotel");//2.准备DSl//2.1设置sizerequest.source().size(0);//2.2聚合request.source().aggregation(AggregationBuilders.terms("brandAgg").field("brand").size(10));//3.发出请求SearchResponse response = client.search(request, RequestOptions.DEFAULT);//4.解析结果System.out.println(response);} 
结果解析
@Testvoid testAggregation() throws IOException {//1.准备RequestSearchRequest request = new SearchRequest("hotel");//2.准备DSl//2.1设置sizerequest.source().size(0);//2.2聚合request.source().aggregation(AggregationBuilders.terms("brandAgg").field("brand").size(10));//3.发出请求SearchResponse response = client.search(request, RequestOptions.DEFAULT);//4.解析结果Aggregations aggregations = response.getAggregations();//4.1根据聚合名称获取聚合结果Terms brandTerms = aggregations.get("brandAgg");//4.2获取bucketsList<? extends Terms.Bucket> buckets = brandTerms.getBuckets();//4.3遍历for (Terms.Bucket bucket : buckets) {//4.4获取keyString key = bucket.getKeyAsString();System.out.println(key);}} 
多条件聚合
在Service中
将公共代码抽取出来，提高复用性
@Overridepublic Map<String, List<String>> filters() {try {//1.准备RequestSearchRequest request = new SearchRequest("hotel");//2.准备DSl//2.1设置sizerequest.source().size(0);//2.2聚合buildAggregation(request);//3.发出请求SearchResponse response = client.search(request, RequestOptions.DEFAULT);//4.解析结果Map<String, List<String>>result=new HashMap<>();Aggregations aggregations = response.getAggregations();//5.1根据品牌名称获取品牌结果List<String> brandList = getAggByName(aggregations,"brandAgg");result.put("品牌",brandList);//5.2根据品牌名称获取品牌结果List<String> cityList = getAggByName(aggregations,"cityAgg");result.put("城市",cityList);//5.3根据品牌名称获取品牌结果List<String> starList = getAggByName(aggregations,"starAgg");result.put("星级",starList);return result;} catch (IOException e) {throw new RuntimeException(e);}}private static List<String> getAggByName(Aggregations aggregations,String aggName) {//4.1根据聚合名称获取聚合结果Terms brandTerms = aggregations.get(aggName);//4.2获取bucketsList<? extends Terms.Bucket> buckets = brandTerms.getBuckets();//4.3遍历List<String>brandList=new ArrayList<>();for (Terms.Bucket bucket : buckets) {//4.4获取keyString key = bucket.getKeyAsString();brandList.add(key);}return brandList;}
在一个测试类中
@SpringBootTest
class HotelDemoApplicationTests {@Autowiredprivate IHotelService hotelService;@Testvoid contextLoads() {Map<String, List<String>> filters = hotelService.filters();System.out.println(filters);}}运行得到
带过滤条件的聚合
在查询的时候要在查询结果上做聚合，不应该直接将所有数据的聚合结果返回。
所以就是加上query参数。
Controller中
传递的参数和正常参数一模一样
@PostMapping("filters")public Map<String, List<String>> getFilters(@RequestBody RequestParams Params){return hotelService.filters(Params);}Service中
添加传递参数，并且新设置了2.3query，使用搜索时同款的query设置方法
@Overridepublic Map<String, List<String>> filters(RequestParams Params) {try {//1.准备RequestSearchRequest request = new SearchRequest("hotel");//2.准备DSl//2.1设置sizerequest.source().size(0);//2.2聚合buildAggregation(request);//2.3querybuildBasicQuery(Params, request);//3.发出请求SearchResponse response = client.search(request, RequestOptions.DEFAULT);//4.解析结果Map<String, List<String>>result=new HashMap<>();Aggregations aggregations = response.getAggregations();//5.1根据品牌名称获取品牌结果List<String> brandList = getAggByName(aggregations,"brandAgg");result.put("品牌",brandList);//5.2根据品牌名称获取品牌结果List<String> cityList = getAggByName(aggregations,"cityAgg");result.put("城市",cityList);//5.3根据品牌名称获取品牌结果List<String> starList = getAggByName(aggregations,"starAgg");result.put("星级",starList);return result;} catch (IOException e) {throw new RuntimeException(e);}}结果测试
根据搜索框和过滤条件成功过滤
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