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法律研究如何使用 Java 从集合中删除多个文档？
在 Java 中，com.mongodb.client.MongoCollection 接口提供了一个 deleteMany()方法。使用此方法，您可以一次从集合中删除多个文档，需要向此方法传递指定删除条件的 filter。
示例
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.bson.Document;
import org.bson.conversions.Bson;
import com.mongodb.MongoClient;
public class DeletingMultipleDocuments {
public static void main( String args[] ) {
//Creating a MongoDB client
MongoClient mongo = new MongoClient( "localhost" , 27017 );
//Connecting to the database
MongoDatabase database = mongo.getDatabase("myDatabase");
//Creating a collection object
MongoCollection<Document>collection = database.getCollection("students");
Document document1 = new Document("name", "Ram").append("age", 26).append("city", "Delhi");
Document document2 = new Document("name", "Robert").append("age", 27).append("city", "Vishakhapatnam");
Document document3 = new Document("name", "Rhim").append("age", 30).append("city", "Delhi");
Document document4 = new Document("name", "Radha").append("age", 45).append("city", "Delhi");
Document document5 = new Document("name", "Sarmista").append("age", 35).append("city", "Mumbai");
//Inserting the created documents
List<Document> list = new ArrayList<Document>();
list.add(document1);
list.add(document2);
list.add(document3);
list.add(document4);
list.add(document5);
collection.insertMany(list);
System.out.println("Documents Inserted");
System.out.println("Contents of the collection:");
FindIterable<Document> iterDoc = collection.find();
int i = 1;
System.out.println("Remaining documents:");
Iterator it = iterDoc.iterator();
while (it.hasNext()) {
System.out.println(it.next());
i++;
}
collection = database.getCollection("students");
//Deleting multiple documents
Bson filter = new Document("city", "Delhi");
collection.deleteMany(filter);
System.out.println("Document deleted successfully...");
//Retrieving the documents after the delete operation
iterDoc = collection.find();
System.out.println("Remaining documents:");
it = iterDoc.iterator();
while (it.hasNext()) {
System.out.println(it.next());
i++;
}
}
}输出
Documents Inserted
Contents of the collection:
Remaining documents:
Document{{_id=5e896b042e4a2f3badebddae, name=Ram, age=26, city=Delhi}}
Document{{_id=5e896b042e4a2f3badebddaf, name=Robert, age=27, city=Vishakhapatnam}}
Document{{_id=5e896b042e4a2f3badebddb0, name=Rhim, age=30, city=Delhi}}
Document{{_id=5e896b042e4a2f3badebddb1, name=Radha, age=45, city=Delhi}}
Document{{_id=5e896b042e4a2f3badebddb2, name=Sarmista, age=35, city=Mumbai}}
Document deleted successfully...
Remaining documents:
Document{{_id=5e896b042e4a2f3badebddaf, name=Robert, age=27, city=Vishakhapatnam}}
Document{{_id=5e896b042e4a2f3badebddb2, name=Sarmista, age=35, city=Mumbai}}
更新日期： 10-4-2020
859 次浏览
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