Java Mongodb 简明教程

Java & MongoDB - Sorting Documents

若要获取一个集合中已排序的文档，可以使用 collection.find().sort() 方法选择一个集合的已排序文档。

// find sorted documents of a collection
collection.find().sort(new BasicDBObject("First_Name",-1));

Example

以下是显示已排序文档的代码片段 −

import org.bson.Document;

import com.mongodb.BasicDBObject;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoClient;
import com.mongodb.client.MongoClients;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;

public class Tester {
   public static void main(String[] args) {
      // Creating a Mongo client
      MongoClient mongoClient = MongoClients.create("mongodb://localhost:27017");
      MongoDatabase database = mongoClient.getDatabase("myDb");

      // Get the collection
      MongoCollection<Document> collection = database.getCollection("sampleCollection");
      System.out.println("***Discending Order***");

      // Sort in Descending order
      FindIterable<Document> allDocuments = collection.find().sort(new BasicDBObject("First_Name",-1));

      for (Document document : allDocuments) {
         System.out.println(document);
      }
      System.out.println("***Ascending Order***");

      // Sort in Ascending order
      allDocuments = collection.find().sort(new BasicDBObject("First_Name",1));

      for (Document document : allDocuments) {
         System.out.println(document);
      }
   }
}

现在，我们按照以下步骤编译并运行上述程序。

$javac Tester.java
$java Tester

Output

在执行上述程序时，您将得到以下输出。

Document{{_id=60b70d426214461f10ac5c9a, First_Name=Radhika, Last_Name=Sharma, Date_Of_Birth=1995-09-26, e_mail=radhika_sharma.123@gmail.com, phone=9000012345}}
Document{{_id=60b70d426214461f10ac5c9b, First_Name=Rachel, Last_Name=Christopher, Date_Of_Birth=1990-02-16, e_mail=Rachel_Christopher.123@gmail.com, phone=9000054321}}
Document{{_id=60b70d426214461f10ac5c9c, First_Name=Fathima, Last_Name=Sheik, Date_Of_Birth=1990-02-16, e_mail=Fathima_Sheik.123@gmail.com, phone=9000054321}}
***Ascending Order***
Document{{_id=60b70d426214461f10ac5c9c, First_Name=Fathima, Last_Name=Sheik, Date_Of_Birth=1990-02-16, e_mail=Fathima_Sheik.123@gmail.com, phone=9000054321}}
Document{{_id=60b70d426214461f10ac5c9b, First_Name=Rachel, Last_Name=Christopher, Date_Of_Birth=1990-02-16, e_mail=Rachel_Christopher.123@gmail.com, phone=9000054321}}
Document{{_id=60b70d426214461f10ac5c9a, First_Name=Radhika, Last_Name=Sharma, Date_Of_Birth=1995-09-26, e_mail=radhika_sharma.123@gmail.com, phone=9000012345}}