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