elasticsearch 多字段聚合或者对字段子串聚合

以下是字段子串聚合，截取 'your_field' 前八位进行聚合的

        Script script = new Script("doc['your_field'].getValue().substring(0,8)");
        CardinalityAggregationBuilder pointCardinality = AggregationBuilders.cardinality("pointCardinality").script(script).precisionThreshold(400000);
        SearchResponse totalPointResponse = client.prepareSearch("index_name").setTypes("type_name")
                .setQuery(boolQueryBuilder)
                .addAggregation(pointCardinality)
                .execute()
                .actionGet();
        Cardinality cardinalityTotal = totalPointResponse.getAggregations().get("pointCardinality");

多字段聚合，就是需要修改Script内容(plainless)，例如根据条件选取字段等：

eg: 

if(doc['camera_dev_name'].size() != 0){doc['camera_dev_name'].getValue().substring(0,8)}else{doc['ap_dev_name.keyword'].getValue().substring(0,8)}

 只需改变Script内容。