官网：https://spring.io/projects/spring-data-elasticsearch

Spring-data-elasticsearch 应用组成

1、配置Maven依赖

<dependency>
    <groupId>org.elasticsearch</groupId>
    <artifactId>elasticsearch</artifactId>
    <version>6.5.0</version>
</dependency>
<dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-elasticsearch</artifactId>
    <version>3.1.2.RELEASE</version>
</dependency>

2、Spring Bean配置

<context:component-scan base-package="com.hogen.*" />
<elasticsearch:repositories base-package="com.hogen.repositories" />  <!-- 扫描DAO层 -->

<elasticsearch:transport-client id="client" cluster-nodes="localhost:9300,127.0.0.1:9300"/> <!-- 指定集群，端口为TCP服务的端口，而非HTTP服务对应的9200 -->
<bean id="elasticsearchTemplate" class="org.springframework.data.elasticsearch.core.ElasticsearchTemplate">
    <constructor-arg name="client" ref="client" />
</bean>

3、POJO类

public class Person {
    @Id
    @Field(index=false,store=true,type=FieldType.Integer)
    private Integer id;
    @Field(index=true,analyzer="ik",store=true,searchAnalyzer="ik",type=FieldType.Text)
    private String title;
    @Field(index=true,analyzer="ik",store=true,searchAnalyzer="ik",type=FieldType.Text)
    private String content;
}

4、DAO接口

// 会自动生成具体实现
public interface PersonRepository extends ElasticsearchRepository<Person, Integer> {
    List<Person> findByTitle(String title);   // 模糊查询
   @Query("{'bool': {'must' : {'field' : {'title' : '?0'}}}}")   // 指定查询json
    Page<Person> findByTitle(String title, Pageable pageable);   // 分页查询
}

5、Service层

@Service
public class PersonServiceImpl {
    @Autowired
    private ElasticsearchTemplate elasticsearchTemplate;
    @Autowired
    private PersonRepository personRepository;

    public void createIndex() {
        elasticsearchTemplate.createIndex(Person.class);   // 创建索引
        elasticsearchTemplate.putMapping(Person.class);   // 设置映射
    }

    public void save(Person person){
        personRepository.save(person);
    }
    public void delete(Person article) {
        personRepository.delete(article);
    }
    public Iterable<Person> findAll() {
        return personRepository.findAll();
    }

    public List<Person> findByTitle(String title) {
        return personRepository.findByTitle(title);
    }
    public Page<Person> findByTitle(String title, Pageable pageable) {
        return personRepository.findByTitle(title, pageable);
    }
}

6、使用

@Autowired
private PersonServiceImpl personService;

使用场景

1、在RDS中不是索引的字段，但又要被搜索，可以将这个字段和ID存在ES。查询时从ES中找出这条数据的ID，再拿ID去RDS查出完整数据