Cassandra

https://github.com/spring-boot-tutorials/spring-data-cassandra

In this article we will configure Spring Boot to connect to a Cassandra database.

Cassandra Server

Install and run Cassandra server

brew install cassandra
brew services start cassandra

Enter Cassandra Cli

cqlsh

Create a new KEYSPACE in Cassandra

CREATE KEYSPACE my_keyspace WITH replication = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };

Create a table under new KEYSPACE

USE my_keyspace;
CREATE TABLE person (
    id uuid PRIMARY KEY,
    title text,
    publisher text,
    tags set<text>
);

Create Initial Code Base

Go to https://start.spring.io/
Click Add Dependencies, search for Cassandra, then add
Click Add Dependencies, search for Lombok, then add
Click Generate

Dependencies

Dependencies used in pom.xml

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-cassandra</artifactId>
</dependency>
<dependency>
    <groupId>org.instancio</groupId>
    <artifactId>instancio-junit</artifactId>
    <version>5.4.0</version>
</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>

Properties

In src/main/resources/application.properties let’s add the following properties so the Spring Boot application can connect to the Cassandra database

spring.cassandra.keyspace-name=my_keyspace
spring.data.cassandra.port=9142
spring.data.cassandra.contact-points=127.0.0.1
spring.cassandra.local-datacenter=datacenter1

Configuration

Let’s annotate CassandraApplication.java like so:

@SpringBootApplication
@EnableCassandraRepositories(basePackages = "com.example.cassandra")
public class CassandraApplication

Model

Let’s create a new POJO src/main/java/com/example/cassandra/model/Person.java

@Table
@Data
@SuperBuilder
@NoArgsConstructor
public class Person {

    @PrimaryKeyColumn(
            name = "id",
            ordinal = 2,
            type = PrimaryKeyType.CLUSTERED,
            ordering = Ordering.DESCENDING)
    private UUID id;

    @PrimaryKeyColumn(name = "title", ordinal = 0, type = PrimaryKeyType.PARTITIONED)
    private String title;

    @PrimaryKeyColumn(name = "publisher", ordinal = 1, type = PrimaryKeyType.PARTITIONED)
    private String publisher;

    @Column
    private Set<String> tags = new HashSet<>();
}

Repository

Next we will create a Spring repository to CRUD against the database

@Repository
public interface PersonRepository extends CassandraRepository<Person, Long> {
}

Main

Now let’s use this repository.

Go back to CassandraApplication.java and add the following:

...
public class CassandraApplication implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(CassandraApplication.class, args);
    }

    @Autowired
    private PersonRepository personRepository;

    public void run(String... args) throws Exception {
        personRepository.deleteAll();

        // 1. save
        Person person = Person.builder()
                .id(UUID.randomUUID())
                .title("Head First Java")
                .publisher("O'Reilly Media")
                .tags(ImmutableSet.of("Computer", "Software"))
                .build();
        personRepository.save(person);

        // 2. saveAll
        int count = 10;
        List<Person> persons = Instancio.ofList(Person.class)
                .size(count)
                .create();
        persons = personRepository.saveAll(persons);
        System.out.println("2. saveAll");
        persons.forEach(System.out::println);

        // 3. update
        person.setTitle("Head First Java Second Edition");
        person = personRepository.save(person);
        System.out.println("3. " + person);

        // 4. findAll
        persons = personRepository.findAll();
        System.out.println("4. findAll");
        persons.forEach(System.out::println);
    }
}

Run Application

Open terminal at project root and execute the following:

mvn spring-boot:run

There should be no errors and the output will display all the CRUD operations.