一、批量更新

 /**
     * 批量更新的操作
     * @return
     */
    public int batchUpdate(){
        List<StudentDo> list = new ArrayList<>(); //要修改的一批数据
        List<Pair<Query, Update>> updateList = new ArrayList<>(list.size());
        BulkOperations operations = mongoTemplate.bulkOps(BulkOperations.BulkMode.UNORDERED, "w_test1");
        list.forEach(data -> {
            //如果query查询到有数据就更新
            Query query = new Query(new Criteria("_id").is(data.getId()));
            Update update = new Update();
            update.set("stu_name",data.getStuName());
            update.set("updateTime",data.getUpdateTime());

            Pair<Query, Update> updatePair = Pair.of(query, update);
            updateList.add(updatePair);
        });
        operations.upsert(updateList);
        BulkWriteResult result = operations.execute();
        return result.getModifiedCount();
    }