In this blog I will show how easy you can connect to a MongoDB using Spring Data. For installation of MongoDB, go to http://docs.mongodb.org/manual/installation/
The dependencies needed besides standard Spring dependencies are spring-data-mongo and mongo-java-driver.
<dependency>
<groupId>org.mongodb</groupId>
<artifactId>mongo-java-driver</artifactId>
<version>2.12.4</version>
</dependency>
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-mongodb</artifactId>
<version>1.6.0.RELEASE</version>
</dependency>
First lets create some domain objects. Department is a simple object with only only one attribute representing a department.
public class Department {
private final String name;
public Department(String name) {
this.name = name;
}
@Override
public String toString() {
return "Department [name=" + this.name + "]";
}
}
Second domain object is Person, which holds a reference to Department. Is also has an @Id which can be used for retrieval.
import org.springframework.data.annotation.Id;
import java.util.UUID;
public class Person {
@Id
private final UUID id;
private final String name;
private final String title;
private final Department department;
public Person(String name, String title, Department department) {
this.id = UUID.randomUUID();
this.name = name;
this.title = title;
this.department = department;
}
public UUID getId() {
return this.id;
}
@Override
public String toString() {
return "Person{" +
"department=" + department +
", id=" + id +
", name='" + name + '\'' +
", title='" + title + '\'' +
'}';
}
}
Next we need a configuration that connects to the MongoDB and exposes a MongoTemplate that can be injected into repository beans.
import org.springframework.data.mongodb.MongoDbFactory;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.SimpleMongoDbFactory;
import com.mongodb.DB;
import com.mongodb.MongoClient;
@Configuration
@ComponentScan("com.blogspot.jpdevelopment.mongodb")
public class MongoDbConfig {
@Bean
public MongoClient mongoClient() throws UnknownHostException {
return new MongoClient("localhost");
}
@Bean
public DB db() throws UnknownHostException {
return mongoClient().getDB("test");
}
@Bean
public MongoDbFactory mongoDbFactory() throws UnknownHostException {
return new SimpleMongoDbFactory(mongoClient(), "test");
}
@Bean
public MongoTemplate mongoTemplate() throws UnknownHostException {
return new MongoTemplate(mongoDbFactory());
}
}
After setting up the configuration, we can create a Repository.The MongoTemplate is injected and opens up to all CRUD actions.
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.core.query.Criteria;
import org.springframework.data.mongodb.core.query.CriteriaDefinition;
import org.springframework.data.mongodb.core.query.Query;
import org.springframework.stereotype.Repository;
import java.util.UUID;
@Repository
public class PersonRepository {
private static final String PERSON_COLLENCTION = "person";
@Autowired
private MongoTemplate template;
public Person findOne(UUID id) {
CriteriaDefinition criteriaDefinition = Criteria.where("id").is(id);
Query query = new Query();
query.addCriteria(criteriaDefinition);
return this.template.findOne(query, Person.class, PERSON_COLLENCTION);
}
public Person save(Person person) {
template.save(person);
return person;
}
}
Finally lets take it for a spin. Spring is started and the Repository bean is fetched from the ApplicationContext.
First a new Person is stored and then again fetched as a new object and printed.
public class Main {
public static void main(String[] args) {
AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(MongoDbConfig.class);
PersonRepository personRepository = ctx.getBean(PersonRepository.class);
Person newPerson = new Person("Jonas", "Developer", new Department("Dev"));
personRepository.save(newPerson);
Person storedPerson = personRepository.findOne(newPerson.getId());
System.out.println(storedPerson);
}
}
The output will look like this:
Person{department=Department [name=Dev], id=9ae44c1d-a38e-4364-9848-2d7dd6538444, name='Jonas', title='Developer'}
That was the very basic of connection to MongoDB from Java using Spring Data.
