Spring Data Elasticsearch 聚合查询

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如需要统计某件商品的数量，最高价格，最低价格等就用到了聚合查询，就像数据库中的group by

　　　　首先需要注入ElasticsearchTemplate

    @Autowired
     private ElasticsearchTemplate elasticsearchTemplate;

　　　　然后开始操作

    //聚合
    public Map<String, Integer> polymerizationQuery() {
        String aggName = "popularBrand";
        NativeSearchQueryBuilder queryBuilder = new NativeSearchQueryBuilder();
        //聚合
        queryBuilder.addAggregation(AggregationBuilders.terms("popularBrand").field("brand"));
        //查询并返回带聚合结果
        AggregatedPage<Item> result = elasticsearchTemplate.queryForPage(queryBuilder.build(), Item.class);
        //解析聚合
        Aggregations aggregations = result.getAggregations();
        //获取指定名称的聚合
        StringTerms terms = aggregations.get(aggName);
        //获取桶
        List<StringTerms.Bucket> buckets = terms.getBuckets();
        //遍历打印
        Map<String, Integer> map = new HashMap<>();
        for (StringTerms.Bucket bucket : buckets) {
            map.put(bucket.getKeyAsString(), (int) bucket.getDocCount());
            System.out.println("key = " + bucket.getKeyAsString());
            System.out.println("DocCount = " + bucket.getDocCount());
        }
        return map;
    }

　　elasticseach的可视化数据

　　其他方法

（1）统计某个字段的数量
  ValueCountAggregationBuilder vcb=  AggregationBuilders.count("自定义").field("uid");
（2）去重统计某个字段的数量
 CardinalityAggregationBuilder cb= AggregationBuilders.cardinality("distinct_count_uid").field("uid");
（3）聚合过滤
FilterAggregationBuilder fab= AggregationBuilders.filter("uid_filter").filter(QueryBuilders.queryStringQuery("uid:001"));
（4）按某个字段分组
TermsAggregationBuilder tb=  AggregationBuilders.terms("group_name").field("name");
（5）求和
SumAggregationBuilder  sumBuilder=    AggregationBuilders.sum("sum_price").field("price");
（6）求平均
AvgAggregationBuilder ab= AggregationBuilders.avg("avg_price").field("price");
（7）求最大值
MaxAggregationBuilder mb= AggregationBuilders.max("max_price").field("price"); 
（8）求最小值
MinAggregationBuilder min=    AggregationBuilders.min("min_price").field("price");
（9）按日期间隔分组
DateHistogramAggregationBuilder dhb= AggregationBuilders.dateHistogram("dh").field("date");
（10）获取聚合里面的结果
TopHitsBuilder thb=  AggregationBuilders.topHits("top_result");
（11）嵌套的聚合
NestedAggregationBuilder nb= AggregationBuilders.nested("negsted_path").path("quests");
（12）反转嵌套
AggregationBuilders.reverseNested("res_negsted").path("kps ");