mongdb分组 年月日周

 //        project：显示哪几个字段，这里显示createTime字段，and..as是把and后的字段重命名为as后的字段，这里把createTime处理后重命名为date
        //        group：分组操作，这里按date分组，计算数量，结果数量重命名为count
        //        第二个project：previousOperation方法是把_id重命名为date（也就是别名）
        //        sort：结果按照date正序排序
        //        collectionName: 集合名称
        //为了更好的理解and…previousOperation方法的含义，这里解释下：
        //去掉第二个project，结果形如[{"count": 3, "_id": "2019-12-13"}]
        //加上第二个project，结果形如[{"count": 3, "date": "2019-12-13"}]
        Aggregation aggregation =
                Aggregation.newAggregation(Aggregation.project("createDate").and(DateOperators.DateToString.dateOf(
                        "createDate").toString("%Y%u")).as("date"), Aggregation.group("date").count().as("count"),
                        Aggregation.project("date", "count").and("date").previousOperation(),
                        Aggregation.sort(Sort.Direction.ASC, "date"));
        AggregationResults<Annex> result = mongoTemplate.aggregate(aggregation, "annex", Annex.class);
        Document rawResults = result.getRawResults();
        List lists = new ArrayList();
        List results = (List) rawResults.get("results");
        Map map = null;
        for(Object o : results){
            map = new HashMap<>();
            Object count = ((Document) o).get("count");
            Object date = ((Document) o).get("date");
            map.put("count", count);
            map.put("date", date);
            lists.add(map);
        }
        System.out.println(lists);