(三)ElasticSearch7.X之聚合查询java代码（所有队伍的valueCount）

本文链接：https://blog.youkuaiyun.com/xiaohuo0930/article/details/106999974

本文展示了一种使用Elasticsearch进行NBA球员数据查询的方法，通过限定查询特定球队（如休斯顿火箭队），并利用聚合查询功能统计球员的年度数量。代码示例展示了如何构建查询请求、设置查询条件及聚合字段，并解析返回的聚合结果。

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POST /nba/_search
{
    "query": {
    "term": {
    "teamNameEn.keyword": {
        "value": "Rockets"
        }
      }
},
"aggs": {
    "countPlayerYear": {
    "value_count": {
    "field": "playYear"
      }
    }
},
"size": 0
}

    @Test
    public void test02() throws IOException {
        SearchRequest searchRequest = new SearchRequest("nba");
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        //限定了查询的队伍名称
//      searchSourceBuilder.query(QueryBuilders.termQuery("teamName.keyword","火箭")).size(100);
        TermsAggregationBuilder field = AggregationBuilders.terms("teamName").field("teamName.keyword").size(200);
        ValueCountAggregationBuilder valueCountAggregationBuilder = AggregationBuilders.count("playYear").field("playYear");
        TermsAggregationBuilder termsAggregationBuilder = field.subAggregation(valueCountAggregationBuilder);
        searchSourceBuilder.aggregation(termsAggregationBuilder);
        searchRequest.source(searchSourceBuilder);
        SearchResponse search = client.search(searchRequest, RequestOptions.DEFAULT);
        Aggregations aggregations = search.getAggregations();
        //下面获得聚合查询
        for(Aggregation a:aggregations){
            Terms terms = (Terms) a;
            for(Terms.Bucket bucket:terms.getBuckets()){
                System.out.println("key is "+bucket.getKeyAsString());
                //这里是elasticsearch7的重大改动！！！！必须强转。
                ValueCount valueCount = (ValueCount) bucket.getAggregations().asMap().get("playYear");
                double value = valueCount.getValue();
                System.out.println("value is "+value);
            }
        }
    }