Java mongodb聚合计数发生次数

import com.mongodb.MongoClient;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import org.bson.Document;

import java.util.Arrays;

public class AggregationExample {
    public static void main(String[] args) {
        // 连接MongoDB数据库
        MongoClient mongoClient = new MongoClient("localhost", 27017);
        MongoDatabase database = mongoClient.getDatabase("mydb");
        MongoCollection<Document> collection = database.getCollection("mycollection");

        // 构建聚合管道
        Document groupBy = new Document("_id", "$field");
        groupBy.put("count", new Document("$sum", 1));
        Document groupStage = new Document("$group", groupBy);
        Document matchStage = new Document("$match", new Document("count", new Document("$gt", 1)));
        Document sortStage = new Document("$sort", new Document("count", -1));
        Document limitStage = new Document("$limit", 10);
        Iterable<Document> pipeline = Arrays.asList(groupStage, matchStage, sortStage, limitStage);

        // 执行聚合计数操作
        collection.aggregate(pipeline).forEach(document -> System.out.println(document.toJson()));

        // 关闭数据库连接
        mongoClient.close();
    }
}