如何使用MongoDB Java查找一个字段的重复数？

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

import java.util.Arrays;

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

        // 使用聚合框架进行字段重复数的查找
        AggregateIterable<Document> result = collection.aggregate(Arrays.asList(
                new Document("$group", new Document("_id", "$your_field_name").append("count", new Document("$sum", 1))),
                new Document("$match", new Document("count", new Document("$gt", 1)))
        ));

        // 输出结果
        for (Document document : result) {
            System.out.println(document.toJson());
        }

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