A simple Java + MongoDB hello world example – how to connect, create database, collection and document, save, update, remove, get and display document (data).
Tools and technologies used :
- MongoDB 2.2.3
- MongoDB-Java-Driver 2.10.1
- JDK 1.6
- Maven 3.0.3
- Eclipse 4.2
P.S Maven and Eclipse are both optional, just my personal favorite development tool.
1. Create a Java Project
Create a simple Java project with Maven.
mvn archetype:generate -DgroupId=com.mkyong.core -DartifactId=mongodb
-DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false
2. Get Mongo Java Driver
Download mongo-java driver from github. For Maven users, declares mongo-java driver in pom.xml.
pom.xml
<project ...>
<dependencies>
<dependency>
<groupId>org.mongodb</groupId>
<artifactId>mongo-java-driver</artifactId>
<version>2.10.1</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.1</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-eclipse-plugin</artifactId>
<configuration>
<downloadSources>true</downloadSources>
<downloadJavadocs>true</downloadJavadocs>
</configuration>
</plugin>
</plugins>
</build>
</project>
3. Mongo Connection
Connect to MongoDB server. For MongoDB version >= 2.10.0, uses MongoClient.
// Old version, uses Mongo
Mongo mongo = new Mongo("localhost", 27017);
// Since 2.10.0, uses MongoClient
MongoClient mongo = new MongoClient( "localhost" , 27017 );
If MongoDB in secure mode, authentication is required.
MongoClient mongoClient = new MongoClient();
DB db = mongoClient.getDB("database name");
boolean auth = db.authenticate("username", "password".toCharArray());
4. Mongo Database
Get database. If the database doesn’t exist, MongoDB will create it for you.
DB db = mongo.getDB("database name");
Display all databases.
List<String> dbs = mongo.getDatabaseNames();
for(String db : dbs){
System.out.println(db);
}
5. Mongo Collection
Get collection / table.
DB db = mongo.getDB("testdb");
DBCollection table = db.getCollection("user");
Display all collections from selected database.
DB db = mongo.getDB("testdb");
Set<String> tables = db.getCollectionNames();
for(String coll : tables){
System.out.println(coll);
}
Note
In RDBMS, collection is equal to table.
In RDBMS, collection is equal to table.
6. Save example
Save a document (data) into a collection (table) named “user”.
DBCollection table = db.getCollection("user");
BasicDBObject document = new BasicDBObject();
document.put("name", "mkyong");
document.put("age", 30);
document.put("createdDate", new Date());
table.insert(document);
Refer to this Java MongoDB insert example.
7. Update example
Update a document where “name=mkyong”.
DBCollection table = db.getCollection("user");
BasicDBObject query = new BasicDBObject();
query.put("name", "mkyong");
BasicDBObject newDocument = new BasicDBObject();
newDocument.put("name", "mkyong-updated");
BasicDBObject updateObj = new BasicDBObject();
updateObj.put("$set", newDocument);
table.update(query, updateObj);
Refer to this Java MongoDB update example.
8. Find example
Find document where “name=mkyong”, and display it with DBCursor
DBCollection table = db.getCollection("user");
BasicDBObject searchQuery = new BasicDBObject();
searchQuery.put("name", "mkyong");
DBCursor cursor = table.find(searchQuery);
while (cursor.hasNext()) {
System.out.println(cursor.next());
}
Refer to this Java MongoDB search query example.
9. Delete example
Find document where “name=mkyong”, and delete it.
DBCollection table = db.getCollection("user");
BasicDBObject searchQuery = new BasicDBObject();
searchQuery.put("name", "mkyong");
table.remove(searchQuery);
Refer to this Java MongoDB delete example.
10. Hello World
Let review a complete Java + MongoDB example, see comments for self-explanatory.
App.java
package com.mkyong.core;
import java.net.UnknownHostException;
import java.util.Date;
import com.mongodb.BasicDBObject;
import com.mongodb.DB;
import com.mongodb.DBCollection;
import com.mongodb.DBCursor;
import com.mongodb.MongoClient;
import com.mongodb.MongoException;
/**
* Java + MongoDB Hello world Example
*
*/
public class App {
public static void main(String[] args) {
try {
/**** Connect to MongoDB ****/
// Since 2.10.0, uses MongoClient
MongoClient mongo = new MongoClient("localhost", 27017);
/**** Get database ****/
// if database doesn't exists, MongoDB will create it for you
DB db = mongo.getDB("testdb");
/**** Get collection / table from 'testdb' ****/
// if collection doesn't exists, MongoDB will create it for you
DBCollection table = db.getCollection("user");
/**** Insert ****/
// create a document to store key and value
BasicDBObject document = new BasicDBObject();
document.put("name", "mkyong");
document.put("age", 30);
document.put("createdDate", new Date());
table.insert(document);
/**** Find and display ****/
BasicDBObject searchQuery = new BasicDBObject();
searchQuery.put("name", "mkyong");
DBCursor cursor = table.find(searchQuery);
while (cursor.hasNext()) {
System.out.println(cursor.next());
}
/**** Update ****/
// search document where name="mkyong" and update it with new values
BasicDBObject query = new BasicDBObject();
query.put("name", "mkyong");
BasicDBObject newDocument = new BasicDBObject();
newDocument.put("name", "mkyong-updated");
BasicDBObject updateObj = new BasicDBObject();
updateObj.put("$set", newDocument);
table.update(query, updateObj);
/**** Find and display ****/
BasicDBObject searchQuery2
= new BasicDBObject().append("name", "mkyong-updated");
DBCursor cursor2 = table.find(searchQuery2);
while (cursor2.hasNext()) {
System.out.println(cursor2.next());
}
/**** Done ****/
System.out.println("Done");
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (MongoException e) {
e.printStackTrace();
}
}
}
Output…
{ "_id" : { "$oid" : "51398e6e30044a944cc23e2e"} , "name" : "mkyong" , "age" : 30 , "createdDate" : { "$date" : "2013-03-08T07:08:30.168Z"}}
{ "_id" : { "$oid" : "51398e6e30044a944cc23e2e"} , "age" : 30 , "createdDate" : { "$date" : "2013-03-08T07:08:30.168Z"} , "name" : "mkyong-updated"}
Done
Let use mongo console to check the created database “testdb”, collection “user”, and document.
$ mongo
MongoDB shell version: 2.2.3
connecting to: test
> show dbs
testdb 0.203125GB
> use testdb
switched to db testdb
> show collections
system.indexes
user
> db.user.find()
{ "_id" : ObjectId("51398e6e30044a944cc23e2e"), "age" : 30, "createdDate" : ISODate("2013-03-08T07:08:30.168Z"), "name" : "mkyong-updated" }
Download Source Code
Download it – Java-mongodb-hello-world-example.zip (13KB)
I just tried this and it worked first time..a real credit to how well written your tutorial are..bravo!
That’s what I want.
Thank you,
Thanks, good article.
Why when i do tout in android studio it bloc
Thanks mkyong 😀
hi any bady is know how to automate Mongodb Quary
you can prepare a simple scenario using Cucumber and your favorite pr.lang (e.g. java or c#)
“com.mongodb.DB” is now deprecated.
We can use “MongoDatabase database = mongoClient.getDatabase(“myMongoDb”);“ to obtain the database now but with that, many other methods will change, like to get a collection etc.
After downloading MongoDriver 2.9.1, 2.10.1 and so on using maven, I cannot find MongoClient. Can you help me with this?
Never mind.. I got it after series of debugging and internet searches.. Thanks and the articles are really good for a newbie like me
Can you please share how did you do it?
Hi I did know how to set the data type as objectId in mongodb using java. Example “accountId” : ObjectId(“56c3fc7fbb82eeb4039106b7”). Give solution
It’s very urgent
i am trying to insert form data from a jsp page to the mongodb but i am not succeed plz give me any example of jsp+mongodb with form submission please…..
Thanks Mkyong.. helped me a lot.
I was following this tutorial
this is my error: the method put(String, Object) in the type BasicBSONObject is not applicable for the arguments (String, int)
mycode:
BasicDBObject doc = new BasicDBObject();
doc.put(“age”, 20);
hi i was following your tutorial https://mkyong.com/mongodb/java-mongodb-hello-world-example/
this is my error: the method put(String, Object) in the type BasicBSONObject is not applicable for the arguments (String, int)
mycode:
BasicDBObject doc = new BasicDBObject();
doc.put(“age”, 20);
Hello,
I am getting this error when trying to connect to mongodb server through Java code. I am able to connect and run commands in mongo shell. Please help
INFO: Exception in monitor thread while connecting to server xxxxxxx:cccc
com.mongodb.MongoSocketReadException: Exception receiving message
at com.mongodb.connection.InternalStreamConnection.translateReadException(InternalStreamConnection.java:480)
at com.mongodb.connection.InternalStreamConnection.receiveMessage(InternalStreamConnection.java:225)
at com.mongodb.connection.CommandHelper.receiveReply(CommandHelper.java:134)
at com.mongodb.connection.CommandHelper.receiveCommandResult(CommandHelper.java:121)
at com.mongodb.connection.CommandHelper.executeCommand(CommandHelper.java:32)
at com.mongodb.connection.InternalStreamConnectionInitializer.initializeConnectionDescription(InternalStreamConnectionInitializer.java:83)
at com.mongodb.connection.InternalStreamConnectionInitializer.initialize(InternalStreamConnectionInitializer.java:43)
at com.mongodb.connection.InternalStreamConnection.open(InternalStreamConnection.java:115)
at com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:127)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.net.SocketException: Connection reset
at java.net.SocketInputStream.read(SocketInputStream.java:168)
at com.mongodb.connection.SocketStream.read(SocketStream.java:85)
at com.mongodb.connection.InternalStreamConnection.receiveResponseBuffers(InternalStreamConnection.java:491)
at com.mongodb.connection.InternalStreamConnection.receiveMessage(InternalStreamConnection.java:221)
… 8 more
com.mongodb.MongoTimeoutException: Timed out after 30000 ms while waiting for a server that matches ReadPreferenceServerSelector{readPreference=primary}. Client view of cluster state is {type=UNKNOWN, servers=[{address=czcholsint755.prg-dc.dhl.com:5556, type=UNKNOWN, state=CONNECTING, exception={com.mongodb.MongoSocketReadException: Exception receiving message}, caused by {java.net.SocketException: Connection reset}}]
at com.mongodb.connection.BaseCluster.createTimeoutException(BaseCluster.java:370)
at com.mongodb.connection.BaseCluster.selectServer(BaseCluster.java:101)
at com.mongodb.binding.ClusterBinding$ClusterBindingConnectionSource.(ClusterBinding.java:75)
at com.mongodb.binding.ClusterBinding$ClusterBindingConnectionSource.(ClusterBinding.java:71)
at com.mongodb.binding.ClusterBinding.getReadConnectionSource(ClusterBinding.java:63)
at com.mongodb.operation.OperationHelper.withConnection(OperationHelper.java:166)
at com.mongodb.operation.ListDatabasesOperation.execute(ListDatabasesOperation.java:100)
at com.mongodb.operation.ListDatabasesOperation.execute(ListDatabasesOperation.java:52)
at com.mongodb.Mongo.execute(Mongo.java:736)
at com.mongodb.Mongo$2.execute(Mongo.java:723)
at com.mongodb.OperationIterable.iterator(OperationIterable.java:47)
at com.mongodb.OperationIterable.forEach(OperationIterable.java:66)
at com.mongodb.MappingIterable.forEach(MappingIterable.java:50)
at com.mongodb.MappingIterable.into(MappingIterable.java:60)
at com.mongodb.Mongo.getDatabaseNames(Mongo.java:420)
at com.dhl.dart.MongoTest.main(MongoTest.java:28)
getDB(String) is deprecated. Use getDatabase(String);
When I try to run I am getting:
“Exception in thread “main” java.lang.NoClassDefFoundError: com/mongodb/MongoException”
I simplified the code way down and am still getting it, also ran the original code (attached archive) and got the same thing.
Is this an issue with how I’m linking mongo to the project or something else?
Thanks for the convenient example, it works perfect!!
No matter what I do, I keep getting package com.mongodb does not exist
Ah, never mind. I was putting the dependency in the wrong place. Not too familiar with maven. Thanks for this tutorial. I use your tutorials all the time. 🙂
thanks for your job
Even after adding the org.mongodb dependency, I am not seeing the mongodb java drivers under the external libraries. Please help
How do you convert the result to String, can you use toString() method?
if table has duplicate clolum value after extecuting below script twice.
db.users.insert({username:”niharika”,password:”123456″})
db.users.insert({username:”niharika”,password:”123456″})
db.users.update({username:”niharika”},{$set:{username:”mkyoung”}})
When we try to updtae the cloumn name it updtae only 1 row. ideally it should update all the rows any suggesstion?
{ “_id” : { “$oid” : “53b2f692d28717367aa9ce28”} , “username” : “niharika” , “password” : “123456”}
{ “_id” : { “$oid” : “53b2fd6ed28717367aa9ce29”} , “username” : “mkyoung” , “password” : “123456”}
public WriteResult update( DBObject q , DBObject o , boolean upsert , boolean multi );
I am fresher in development .
Really this is nice project/example to beginner..
Thank you very much……
Also found more elaboration on how to create collections more explicitly i.e capped collections.
http://lotusmediacentre.com/mongodb-java-hello-world-example/
When we run example code . After successful execution of code … whey the java code is not terminating ?
how should i set timeout for same example ?
dont you want to close the connections?
Hi mkyong,
Thanks for your sharing your knowledge with us.They are really helpful for us
Instead of creating a maven project are there any jars that we can import and then import them?
Instead of creating a maven project are there any jars that we can import and then use those instead of pom.xml dependencies?
Why would you ever want to do that? Maven has made everything so easy.
i just did tried that there are 3 jars listed below that i used, and copied the above sample program it worked just fine
1. mongo-2.10.1.jar
2. mongoconnector.jar
3. mongo-java-driver-2.10.1-javadoc.jar
and you will be good to go
Some more examples
http://www.pretechsol.com/p/nosql_20.html#.UeZpTRnZhaE
For a beginner like me , your tutorials are too good. I appreciate the work that you do to make people understand all the concepts.
Thanks a lot.
Do not need mongoClient.close() in example source?
use only upper code then mongo has too many client connection
then it works slower
Nice one . Good as a starter ! . Appreciate your effort .
I have worked on Spring data integration with mango db in java application, can this be done in struts application aslo, I tried to find some examples online but could not find any.
Absolutely yes, Spring is build for integration, Google Spring + Struts integration example.
Excellent and very useful for beginers.
It fails:
03-May-2011 11:32:58 com.mongodb.DBTCPConnector fetchMaxBsonObjectSize
WARNING: null
java.io.IOException: couldn’t connect to [HOSTNAME/HOSTIP:27017] bc:java.net.ConnectException: Connection refused: connect
at com.mongodb.DBPort._open(DBPort.java:205)
(…)
obviously, cant connect to your mongodb.
Make sure your mongodb is started and you are able to connect with the build-in mongo client.
thanks, i’ll try that.
I ran into a similar issue using the Java driver connecting to a server (mongod.exe). Make sure you use the -rest flag. That seemed to work for me.