使用 Java 在 MongoDB 中创建集合

Create Collection in MongoDB Using Java

提问by user3219005

i want to create collection in mongodb using java.The below is the code i worked with.I can connect to database.But Collection is not happening..please help me

我想使用 java 在 mongodb 中创建集合。下面是我使用的代码。我可以连接到数据库。但是集合没有发生..请帮助我

   import com.mongodb.MongoClient;
   import com.mongodb.DB;
   import com.mongodb.DBCollection;

   public class CreateCollection{

     public static void main( String args[] ){
       try{   

         // To connect to mongodb server
         MongoClient mongoClient = new MongoClient( "localhost" , 27017 );

         // Now connect to your databases
         DB db = mongoClient.getDB( "cms" );
         System.out.println("Connect to database successfully");

         DBCollection school = db.createCollection("college");
         System.out.println("Collection mycol created successfully");

       }catch(Exception e){
         System.err.println( e.getClass().getName() + ": " + e.getMessage() );
       }
    } 
  }

回答by Ori Dar

Indeed you have a compilation error.

确实，您有编译错误。

You should use db.getCollection("college")which creates the collection if not exist.

db.getCollection("college")如果不存在，您应该使用which 创建集合。

Also, the collection is lazily created when you add something to it.

此外，当您向其中添加内容时，该集合是惰性创建的。

You can add:

你可以加：

school.save(new BasicDBObject("key" , "value"));

school.save(new BasicDBObject("key" , "value"));

The collection with a single document will be created then.

然后将创建具有单个文档的集合。

回答by Jared Darling

I just recently needed to do this very thing.

我只是最近需要做这件事。

Here is what I used (adapted to your question):

这是我使用的（适应您的问题）：

String collectionName = "college");

if(!db.collectionExists(collectionName)
{
  //I can confirm that the collection is created at this point.
  DBCollection school = db.createCollection(collectionName, new BasicDBObject());      
  //I would highly recommend you check the 'school' DBCollection to confirm it was actually created
  System.out.println("Collection %s created successfully", collectionName);
}

回答by Rajan Kumar Yadav

Here I am sharing the working code

在这里我分享工作代码

import com.mongodb.MongoClient;
import com.mongodb.MongoException;
import com.mongodb.WriteConcern;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.BasicDBObject;
import com.mongodb.DBObject;
import com.mongodb.DBCursor;
import com.mongodb.ServerAddress;
import java.util.Arrays;

public class MongoDBCollection
{

public static void main(String args[])
{
try
{
//Connect to Database
MongoClient mongoClient=new MongoClient("localhost",27017);
DB db=mongoClient.getDB("analytics");
System.out.println("Your connection to DB is ready for Use::"+db);

//Create Collection

DBCollection linked=db.createCollection("LinkedIn",new BasicDBObject()); 
System.out.println("Collection created successfully");

}

catch(Exception e)
{
System.out.println(e.getClass().getName()+":"+e.getMessage());

}

}


}

回答by Stas

Here is my way

这是我的方式

        MongoCollection collection;
        String collectionName = "somename";
        String jsonObject = "{}";

        if (!mongoTemplate.collectionExists(collectionName)) {
            collection = mongoTemplate.createCollection(collectionName);
            logger.info("Collection %s was successfully created", collectionName);
        } else {
            collection = mongoTemplate.getCollection(collectionName);
        }

        collection.insertOne(Document.parse(jsonObject));