jave查询elasticSearch过滤掉字段为null的数据

BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
        //按照分类进行过滤查询
        if (attrType != null && attrType.length > 0) {
            //过滤精准匹配，用作查询具体的分类
            boolQueryBuilder.must(QueryBuilders.termsQuery("attr_type", attrType));
        }
        //档案类型过滤
        if (docType != null && docType.length > 0) {
            //过滤精准匹配，用作查询具体的分类
            boolQueryBuilder.filter(QueryBuilders.termsQuery("doc_type", docType));
        }
        boolQueryBuilder.must(QueryBuilders.existsQuery("title"));