In this example I am going to show you how to post data to a MongoDB database using Spring Data Mongo in Java using Spring, Spring Java Configuration, Maven and Log4J.

Spring Java Configuration

Let’s take a quick look at the Spring Java Configuration file that the project is going to be using

@Configuration
@EnableMongoRepositories
@ComponentScan(basePackageClasses = {MongoDBApp.class})
@PropertySource("classpath:application.properties")
public class MongoConfiguration extends AbstractMongoConfiguration
{


    @Override
    protected String getDatabaseName() {
        return "demo";
    }

    @Override
    public Mongo mongo() throws Exception {
        return new Mongo();
    }

    @Override
    protected String getMappingBasePackage() {
        return "com.johnathanmarksmith.mongodb.example.domain";
    }

}

As you can see from the above code the trick to all this is to use @EnableMongoRepositories and to extend your class from AbstractMongoConfiguration.

The Person Object

Now we are going to take a look at the object that we are going to be inserting into the database.

    @Document
    public class Person {

    @Id
    private String personId;

    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getPersonId() {
        return personId;
    }

    public void setPersonId(final String personId) {
        this.personId = personId;
    }

    public String getName() {
        return name;
    }

    public void setName(final String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(final int age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "Person [id=" + personId + ", name=" + name
                + ", age=" + age +  "]";
    }

}

You see we use the @Document and the @Id.

The Repository

Now its time to see the source code in the repository

@Repository
public class PersonRepository {

    static final Logger logger = LoggerFactory.getLogger(PersonRepository.class);

    @Autowired
    MongoTemplate mongoTemplate;

    public void countUnderAge() {
        List<Person> results = null;

        Query query = new Query();
        Criteria criteria = new Criteria();
        criteria = criteria.and("age").lte(21);

        query.addCriteria(criteria);
        results = mongoTemplate.find(query, Person.class);

        logger.info("Total number of under age in database: {}", results.size());
    }

    /**
     * This will count how many Person Objects I have
     */
    public void countAllPersons() {
        List<Person> results = mongoTemplate.findAll(Person.class);
        logger.info("Total number in database: {}", results.size());
    }

    /**
     * This will install a new Person object with my
     * name and random age
     */
    public void insertPersonWithNameJohnathanAndRandomAge() {

        double age = Math.ceil(Math.random() * 100);
        Person p = new Person("Johnathan", (int) age);

        mongoTemplate.insert(p);
    }

    /**
     * this will create a {@link Person} collection if the collection does not already exists
     */
    public void createPersonCollection() {
        if (!mongoTemplate.collectionExists(Person.class)) {
            mongoTemplate.createCollection(Person.class);
        }
    }

    /**
     * this will drop the {@link Person} collection if the collection does already exists
     */
    public void dropPersonCollection() {
        if (mongoTemplate.collectionExists(Person.class)) {
            mongoTemplate.dropCollection(Person.class);
        }
    }
}

The Main Class

Time for the main class now.. are you ready for all this code??

    public static void main(String[] args) {
        logger.info("MongoDemo application");

        ApplicationContext context = new AnnotationConfigApplicationContext(MongoConfiguration.class);

        PersonRepository personRepository = context.getBean(PersonRepository.class);

        // cleanup person collection before insertion
        personRepository.dropPersonCollection();

        //create person collection
        personRepository.createPersonCollection();

        for (int i = 0; i < 10000; i++) {
            personRepository.insertPersonWithNameJohnathanAndRandomAge();
        }

        personRepository.countAllPersons();


        /***
         *
         * Added Under Age Test For someone to see
         *
         */
        personRepository.countUnderAge();


        logger.info("MongoDemo application");
    }
}

You can see from the above code how easy it is to use Spring Data Mongo to post data to a MongoDB.

Download and Run Code

You can checkout the project from github.

git clone git@github.com:JohnathanMarkSmith/spring-mongo-demo.git
cd spring-mongo-demo
mvn clean package
mvn exec:java

Please keep in mind to be able to run this demo application start your MongoDB instance, Yes you need MongoDB.

If you have any questions or comments please email me at john@johnathanmarksmith.com or checkout my web site http://JohnathanMarkSmith.com

For a MongoDB guide see http://www.mongodb.org/display/DOCS/Quickstart

Thanks, Johnathan Mark Smith