按时间间隔分组spring-data-mongo

import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.aggregation.Aggregation;
import org.springframework.data.mongodb.core.aggregation.GroupOperation;
import org.springframework.data.mongodb.core.aggregation.TypedAggregation;
import org.springframework.data.mongodb.core.query.Criteria;

import java.util.Date;
import java.util.List;

public class GroupByTimeIntervalExample {

    private final MongoTemplate mongoTemplate;

    public GroupByTimeIntervalExample(MongoTemplate mongoTemplate) {
        this.mongoTemplate = mongoTemplate;
    }

    public List<GroupResult> groupByTimeInterval(Date startDate, Date endDate, long interval) {
        GroupOperation groupOperation = Aggregation.group(getTimeIntervalField(interval))
                .count().as("count");

        TypedAggregation aggregation = Aggregation.newAggregation(
                Aggregation.match(Criteria.where("date").gte(startDate).lte(endDate)),
                groupOperation
        );

        return mongoTemplate.aggregate(aggregation, "collectionName", GroupResult.class).getMappedResults();
    }

    private String getTimeIntervalField(long interval) {
        // 根据时间间隔计算字段名，例如每小时分组可以使用"$hour"，每天分组可以使用"$dayOfMonth"等
        // 这里只是示例，具体根据实际需求进行计算
        return "$hour";
    }

    public static class GroupResult {
        private int timeInterval;
        private long count;

        // getter and setter
    }
}