JAVA Rest High Level Client如何取聚合后得数据

对于刚刚学习es的童鞋来说，很容易不清楚怎么获取客户端对es文档的聚合结果，下面就演示一下模仿DSL写聚合，然后获取到聚合的结果。

一， 对于下面这个简单的聚合，目的是对于文档全文匹配，聚合颜色字段。把满足匹配的文档放入自定义名称的colors桶中，参照《elasticsearch权威指南》的范围限定聚合

 1 {
 2     "size" : 0,
 3     "query" : {
 4         "match_all" : {}
 5     },
 6     "aggs" : {
 7         "colors" : {
 8             "terms" : {
 9               "field" : "color"
10             }
11         }
12     }
13 }

二， 对照着这个DSL写我们的java rest client api的调用方法，供业务层调用

 1     /**
 2      * ES中查询所有color
 3      *
 4      * @param indices
 5      * @return
 6      */
 7     public SearchResponse getAllColor(String... indices) {
 8         SearchRequest searchRequest = new SearchRequest(indices);
 9         SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder().size(0);
10         searchSourceBuilder.query(QueryBuilders.matchAllQuery());
11         TermsAggregationBuilder builder = AggregationBuilders.terms("colors").field("color");
12         searchSourceBuilder.aggregation(builder);
13         searchRequest.source(searchSourceBuilder);
14 
15         try {
16             return client.getHighLevelClient().search(searchRequest);
17         } catch (IOException e) {
18             throw new BizException("聚合失败：{}", e.getCause());
19         }
20     }

三， 在我们的业务层调用上文中的getAllColor方法获取response，对response解析，获取聚合的结果

 2      * 颜色信息
 3      *
 4      * @return
 5      */
 6     public List getAllColorInfo() {
 7         SearchResponse response = highRestHelper.getAllColor(getIndices());
 8         Aggregations aggregations = response.getAggregations();
 9         ParsedStringTerms colorTerms = aggregations.get("app_group");
10         List colors = new ArrayList<>();
11         Listextends Terms.Bucket> buckets = colorTerms.getBuckets();
12         for (Terms.Bucket bucket : buckets) {
13             String appName = bucket.getKey().toString();
14             colors.add(appName);
15         }   
16         return colors;
17     } 

至此即可获取所有的聚合结果，只要能够参照DSL，转换成相应的api调用，那么解析过程完全可以复用。