使用java根据条件从mongo集合中获取平均值

import com.mongodb.MongoClient;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;

public class Main {
    public static void main(String[] args) {
        // 建立与MongoDB的连接
        MongoClient mongoClient = new MongoClient("localhost", 27017);
        
        // 选择数据库
        MongoDatabase database = mongoClient.getDatabase("your_database_name");
        
        // 选择集合
        MongoCollection<Document> collection = database.getCollection("your_collection_name");
        
        // 其他操作...
    }
}

import com.mongodb.client.AggregateIterable;
import org.bson.Document;

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        // 其他代码...
        
        // 构建聚合管道
        Document match = new Document("$match", new Document("your_field", "your_condition"));
        Document group = new Document("$group", new Document("_id", null).append("avgValue", new Document("$avg", "$your_field")));
        AggregateIterable<Document> result = collection.aggregate(Arrays.asList(match, group));
        
        // 获取平均值
        double avgValue = result.first().getDouble("avgValue");
        
        System.out.println("平均值：" + avgValue);
        
        // 其他操作...
    }
}