springboot2.3配置与使用elasticsearch7.x

网上很多都过时了，我总结了一下新版的。
首先，springboot配置elasticsearch，不要再用下面这写了，jest完全过时了，别再用了

Client

一共有三种支持的Client

现在spring官方推荐我们用High Level REST Client来配置
具体配置如下

@Configuration
public class ElasticSearchConfig extends AbstractElasticsearchConfiguration {
    @Bean
    public RestHighLevelClient restHighLevelClient(){
        ClientConfiguration configuration = ClientConfiguration.builder(
        )
                .connectedTo("192.168.100.126:9200")
                //.withConnectTimeout(Duration.ofSeconds(5))
                //.withSocketTimeout(Duration.ofSeconds(3))
                //.useSsl()
                //.withDefaultHeaders(defaultHeaders)
                //.withBasicAuth(username, password)
                // ... other options
                .build();
        RestHighLevelClient client = RestClients.create(configuration).rest();
        return client;
    }
}

Transport client将会再ES8.0中被弃用。可以看到ElasticsearchTemplate是基于Transport client

再写一个JavaBean来用测试

//6.0版本后，一个index只有一个type了,这里type也被移除。ES默认type为“_doc”
@Document(indexName = "at")
public class Book {
    private Integer id;
    private String bookname;
    private String author;
    //get set 构造函数，toString的得写上，这里太长就删了先

}

操作ES有两大类

1. Elasticsearch Repositories
2. Elasticsearch Operations

Elasticsearch Repositories

先用Elasticsearch Repositories，注意接口与接口的关系是extends

@Repository
public interface Bookrepository extends ElasticsearchRepository<Book,Integer> {
    //ElasticsearchCrudRepository 已经过时
    List<Book> findBookById(int i);
}

Elasticsearch Repositories提供了许多关键字，来帮助我们实现方法。我们只需要写抽象方法即可，Elasticsearch Repositories会根据方法名自动我们为我们实现，比如上面find和By就是关键字。
我们需要在springboot主配置类上加上注解@EnableElasticsearchRepositories
可以使用Elasticsearch提供的的关键字（方法）列表
,常用关键字如下

然后测试一下

@SpringBootTest
class ElasticsearchApplicationTests {

    @Autowired
    Bookrepository bookrepository;

    @Test
    void contextLoads() {
        Book book=new Book(1,"西游记","吴承恩");
        bookrepository.save(book);
    }

    @Test
    void testRepositories(){
        //查询
        //Elasticsearch Repositories提供and,by等一大堆关键字来连接JAVABEAN属性，我们写接口，他自动变成为实现类。
        List<Book> bookById = bookrepository.findBookById(1);
        System.out.println(bookById.get(0));
    }

}

结果

Elasticsearch Operations

ElasticsearchTemplate是基于Transport client的,Transport client将会再ES8.0中被弃用,用谁不用我多说了吧。
使用Elasticsearch Operations我们需要修改上面的配置类，需要继承AbstractElasticsearchConfiguration，因为基类AbstractElasticsearchConfiguration已经提供了ElasticsearchRestTemplate这个bean

@Configuration
public class RestClientConfig extends AbstractElasticsearchConfiguration {

    @Override
    public RestHighLevelClient elasticsearchClient() {
        ClientConfiguration configuration = ClientConfiguration.builder(
        )
                .connectedTo("192.168.100.126:9200")//9300会报错
                //.withConnectTimeout(Duration.ofSeconds(5))
                //.withSocketTimeout(Duration.ofSeconds(3))
                //.useSsl()
                //.withDefaultHeaders(defaultHeaders)
                //.withBasicAuth(username, password)
                // ... other options
                .build();
        RestHighLevelClient client = RestClients.create(configuration).rest();
        return client;
    }
}

使用方法

@SpringBootTest
class ElasticsearchApplicationTests {

    @Autowired
    ElasticsearchOperations elasticsearchOperations;

    @Test
    void testSaveByOperations(){
        Book book=new Book(2,"西游记2","吴承恩二世");
        IndexQuery indexQuery= new IndexQueryBuilder()
                .withId(book.getId().toString())
                .withObject(book)
                .build();
        String documentId = elasticsearchOperations.index(indexQuery, IndexCoordinates.of("at"));//返回_id(并非javabean中的ID，而是hits中的)
        System.out.println(documentId);
    }

    @Test
    void testFindByOperations(){
        Book book = elasticsearchOperations.get("2",Book.class,IndexCoordinates.of("at"));//IndexCoordinates的参数为Index
        System.out.println(book);
    }


}

结果