如何使用Java更新MongoDB集合中的多个文档？
使用updateMany()方法可以更新集合的所有文档。
语法
db.COLLECTION_NAME.update(<filter>, <update>)
在Java中，com.mongodb.client.MongoCollection接口为您提供了一个具有相同名称的方法。使用此方法，您可以一次更新集合中的多个文档，为此，您需要传递更新的过滤器和值。
示例
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.Filters;
import com.mongodb.client.model.Updates;
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 UpdatingMultipleDocuments {
public static void main( String args[] ) {
//创建一个Mongo客户端
MongoClient mongo = new MongoClient( "localhost" , 27017 );
//连接到数据库
MongoDatabase database = mongo.getDatabase("myDatabase");
//创建一个收集对象
MongoCollection<Document>collection =
database.getCollection("myCollection");
//准备文件
Document document1 = new Document("name", "Ram").append("age", 26).append("city", "Hyderabad");
Document document2 = new Document("name", "Robert").append("age", 27).append("city", "Delhi");
Document document3 = new Document("name", "Rahim").append("age", 30).append("city", "Delhi");
//插入创建的文档
List<Document> list = new ArrayList<Document>();
list.add(document1);
list.add(document2);
list.add(document3);
collection.insertMany(list);
System.out.println("List of the documents: ");
FindIterable<Document> iterDoc = collection.find();
Iterator it = iterDoc.iterator();
while (it.hasNext()) {
System.out.println(it.next());
}
//更新多个文档
Bson filter = new Document("city", "Delhi");
Bson newValue = new Document("city", "Vijayawada");
Bson updateOperationDocument = new Document("$set", newValue);
collection.updateMany(filter, updateOperationDocument);
System.out.println("Document update successfully...");
System.out.println("List of the documents after update");
iterDoc = collection.find();
it = iterDoc.iterator();
while (it.hasNext()) {
System.out.println(it.next());
}
}
}输出结果
List of the documents:
Document{{_id=5e88a61fe7a0124a4fc51b2c, name=Ram, age=26, city=Hyderabad}}
Document{{_id=5e88a61fe7a0124a4fc51b2d, name=Robert, age=27, city=Delhi}}
Document{{_id=5e88a61fe7a0124a4fc51b2e, name=Rahim, age=30, city=Delhi}}
Document update successfully...
List of the documents after update
Document{{_id=5e88a61fe7a0124a4fc51b2c, name=Ram, age=26, city=Hyderabad}}
Document{{_id=5e88a61fe7a0124a4fc51b2d, name=Robert, age=27, city=Vijayawada}}
Document{{_id=5e88a61fe7a0124a4fc51b2e, name=Rahim, age=30, city=Vijayawada}}