We often use Elasticsearch to improve performance in our application, especially searching and caching, to make our application scale and adapt in real-time.

Elasticsearch is a flexible and powerful open source, distributed, real-time search and analytics engine. In this article, I would like to introduce how to use Elasticsearch in java applications: by using Spring Boot data Elasticsearch. Spring Boot now easy and powerful, and we can build fast Java and web applications with a simple configuration.

By following the steps below, you can start writing your first application.

Source code: https://github.com/herotl2005/spring-data-elasticsearch-sample

Requirement enviroment

1. Install Elasticsearch

2. Install Gradle

3. IDE Eclipse or Intellij  IDEA

Step by Step Coding

1. Gradle build 

dependencies {
testCompile group: 'junit', name: 'junit', version: '4.11'
compile 'org.springframework.boot:spring-boot-starter-data-elasticsearch:1.2.0.RELEASE'
compile 'org.springframework.data:spring-data-cassandra:1.1.1.RELEASE'
compile 'org.springframework:spring-test:4.1.2.RELEASE'
compile 'org.springframework.boot:spring-boot-starter-logging:1.2.0.RELEASE'
compile 'org.springframework.boot:spring-boot-starter-web:1.2.0.RELEASE'
compile 'org.springframework.boot:spring-boot-starter-actuator:1.2.0.RELEASE'
}

2. Elasticsearch configuration

@Configuration@PropertySource(value = "classpath:elasticsearch.properties")
@EnableElasticsearchRepositories(basePackages = "co.paan.repository")
public class ElasticsearchConfiguration {
    @Resource
private Environment environment;
@Bean
public Client client() {
        TransportClient client = new TransportClient();
TransportAddress address = new InetSocketTransportAddress(environment.getProperty("elasticsearch.host"), Integer.parseInt(environment.getProperty("elasticsearch.port")));
client.addTransportAddress(address);        
return client;
}

    @Beanpublic ElasticsearchOperations elasticsearchTemplate() {
        return new ElasticsearchTemplate(client());
     }
}

You put elasticsearch host and post in your application properties file.

elasticsearch.host = localhost
 # if you use you local elasticsearch host
elasticsearch.port = 9300

3. Data mapping object: 

In this application, we have 2 entities data object mapping: Post and Tag

@Document(indexName = "post", type = "post", shards = 1, replicas = 0)
public class Post {
@Idprivate String id;    private String title;// 
@Field(type= FieldType.Nested)
private List<Tag> tags;   
 public String getId() {
        return id;
}

    public void setId(String id) {
        this.id = id;
}

    public String getTitle() {
        return title;
}

    public void setTitle(String title) {
        this.title = title;
}

    public List<Tag> getTags() {
        return tags;
}

    public void setTags(List<Tag> tags) {
        this.tags = tags;}
}

public class Tag {
 private String id;   
 private String name;   
 public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }

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

4. Repository: we extends from ElasticsearchRepository

public interface PostRepository extends ElasticsearchRepository<Post, String>{

    Page<Post> findByTagsName(String name, Pageable pageable);
}

5. Data access service

public interface PostService {
    Post save(Post post);
    Post findOne(String id);
    Iterable<Post> findAll();
    Page<Post> findByTagsName(String tagName, PageRequest pageRequest);
}

@Servicepublic class PostServiceImpl implements PostService{
    @Autowired
private PostRepository postRepository;
@Override
public Post save(Post post) {
        postRepository.save(post);        

              return post;
       }

    @Overridepublic Post findOne(String id) {
        return postRepository.findOne(id);
   }

    @Overridepublic Iterable<Post> findAll() {
        return postRepository.findAll();
   }

    @Overridepublic Page<Post> findByTagsName(String tagName, PageRequest pageRequest) {
        return postRepository.findByTagsName(tagName, pageRequest);
   }
}

6. Testing and the result

@Testpublic void testFindByTagsName() throws Exception {
Tag tag = new Tag();
tag.setId("1");
tag.setName("tech");
Tag tag2 = new Tag();
tag2.setId("2");
tag2.setName("elasticsearch");
Post post = new Post();
post.setId("1");
post.setTitle("Bigining with spring boot application and elasticsearch");
post.setTags(Arrays.asList(tag, tag2));
postService.save(post);
Post post2 = new Post();
post2.setId("1");
post2.setTitle("Bigining with spring boot application");
post2.setTags(Arrays.asList(tag));
postService.save(post);
Page<Post> posts  = postService.findByTagsName("tech", new PageRequest(0,10));Page<Post> posts2  = postService.findByTagsName("tech", new PageRequest(0,10));Page<Post> posts3  = postService.findByTagsName("maz", new PageRequest(0,10));assertThat(posts.getTotalElements(), is(1L));
assertThat(posts2.getTotalElements(), is(1L));
assertThat(posts3.getTotalElements(), is(0L));
}

7. You can find detail project at github: https://github.com/herotl2005/spring-data-elasticsearch-sample