SpringBoot集成ElasticSearch实现聚合查询

    @Test
    public void testGroup() throws IOException {

        SearchSourceBuilder builder = new SearchSourceBuilder ( );

        BoolQueryBuilder queryBuilder = QueryBuilders.boolQuery ( );

        //聚合查询的过滤条件
        queryBuilder.must ( QueryBuilders.termQuery ("age", "女") )
                .filter (QueryBuilders.rangeQuery ("age").gte (18).lt (23));

        //聚合查询 不查数据 所以这里设置0 根据实际需求来
        builder.size (0);

        builder.query (queryBuilder);

        //聚合查询 terms自定义   field是想要分组的字段
        TermsAggregationBuilder agr = AggregationBuilders.terms ("group_name").field ("grade").size (10);

        //嵌套聚合查询
        agr.subAggregation (AggregationBuilders.avg ("group_avg").field ("age"));

        builder.aggregation (agr);

        //创建查询请求
        SearchRequest request = new SearchRequest ().indices ( "school" );
        request.source (builder);

        SearchResponse search = restHighLevelClient.search (request, RequestOptions.DEFAULT);

        //通过自定义组名 获取结果
        Terms terms = search.getAggregations ( ).get ("group_name");

        for (Terms.Bucket bucket : terms.getBuckets ( )) {
            Avg avg = bucket.getAggregations ( ).get ("group_avg");
            /*
                bucket.getAggregations ( ).get("....")的返回结果有很多种  根据自己的实际情况来定
                1.如果用的是terms 则用Terms接收 
                2.如果用的avg 则用Avg对象进行接收
                3.sum求和 则用Sum接收
                    ...还有很多不依次举例了

                如果是Terms对象 则在嵌套一层for循环进行取值 如果是其他聚合函数直接引用就ok
             
                例如：
                    Terms terms2 = bucket.getAggregations ( ).get ("group_avg");
                    for (Terms.Bucket terms2Bucket : terms2.getBuckets ( )) {
                        terms2Bucket.getKey ( ).toString ( );
                        terms2Bucket.getDocCount ( );
                    }
             */
            System.out.println ("班级名称："+bucket.getKey ( ).toString ( )
                    + " 妹纸数量：" + bucket.getDocCount ( )
                    + "  妹纸平均年级：" + avg.getValue ( ));
        }

    }

API用的是 RestHighLevelClient类