import org.springframework.data.domain.Sort;
import org.springframework.data.domain.Sort.Direction;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.aggregation.Aggregation;
import org.springframework.data.mongodb.core.aggregation.AggregationResults;
import com.mongodb.BasicDBObject;

...
public void xx(){
    // 聚合条件，相当于拼一个groupBy的sql语句
    Aggregation agg = Aggregation.newAggregation(
            Aggregation.match(Criteria.where("duration").lt(300)), // where条件
            Aggregation.group("ipcc").count().as("total"), // group by
            Aggregation.project("total").and("ipcc").previousOperation(), // select字段，默认groupby的那个字段，在结果里字段名是_id，所以用and("ipcc").previousOperation()改为ipcc，挺奇怪的用法。
            Aggregation.sort(Sort.Direction.DESC, "total")); // 排序

    // 执行查询，并把结果转成bean，这里偷懒，用了BasicDBObject这个万能bean
    AggregationResults<BasicDBObject> result = mongoTemplate.aggregate(agg,
            AgentTicketLog.class, BasicDBObject.class);
    List<BasicDBObject> list = result.getMappedResults();
    for (BasicDBObject dbo : list) {
        String key = dbo.getString("ipcc");
        long total = dbo.getLong("total");
        System.out.println(key + ":" + total);
    }
}

{
    "aggregate":"agentTicketLog",
    "pipeline":[
        {
            "$match":{
                "duration":{
                    "$lt":300
                }
            }
        },
        {
            "$group":{
                "_id":"$ipcc",
                "total":{
                    "$sum":1
                }
            }
        },
        {
            "$project":{
                "total":1,
                "_id":0,
                "ipcc":"$_id"
            }
        },
        {
            "$sort":{
                "total":-1
            }
        }
    ]
}