spring mongodb上如何转换$group操作符mongodb

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

// 创建MongoTemplate对象
MongoTemplate mongoTemplate = new MongoTemplate();

// 创建$group操作符
GroupOperation groupOperation = Aggregation.group("field1", "field2")
    .sum("field3").as("sumField")
    .avg("field4").as("avgField");

// 创建AggregationOperation对象
AggregationOperation aggregationOperation = groupOperation;

// 创建TypedAggregation对象
TypedAggregation aggregation = Aggregation.newAggregation(EntityClass.class, aggregationOperation);

// 执行聚合查询
List<AggregationResults<ResultClass>> results = mongoTemplate.aggregate(aggregation, ResultClass.class);

// 获取聚合结果
List<ResultClass> resultList = results.getMappedResults();