@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(RestHighLevelClient.class)
@AutoConfigureAfter({ ElasticsearchRestClientAutoConfiguration.class })
public class ElasticsearchAutoConfiguration {
    @Bean
    @ConditionalOnMissingBean
    public RestHighLevelClient elasticsearchClient(
            RestClientBuilderCustomizer... restClientBuilderCustomizers) throws Exception {
        return new RestHighLevelClient(
                RestClient.builder(getHostsProperties())
                        .setHttpClientConfigCallback(config -> config
                                .setDefaultCredentialsProvider(getCredentialsProvider()))
                        .setRequestConfigCallback(getRequestConfigCallback())
                        .setHttpClientConfigCallback(httpClientBuilder -> {
                            for (RestClientBuilderCustomizer customizer : restClientBuilderCustomizers) {
                                customizer.customize(httpClientBuilder);
                            }
                        }));
    }
    @Bean
    @ConditionalOnMissingBean
    public ElasticsearchRestTemplate elasticsearchRestTemplate(
            RestHighLevelClient elasticsearchClient) {
        return new ElasticsearchRestTemplate(elasticsearchClient);
    }
}

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-elasticsearch</artifactId>
</dependency>

spring:
  elasticsearch:
    rest:
      uris: http://localhost:9200

@Autowired
private ElasticsearchRestTemplate elasticsearchTemplate;
public List<Book> searchBooks(String query) {
    Query searchQuery = new NativeSearchQueryBuilder()
            .withQuery(Query# Spring Boot中的Elasticsearch自動(dòng)配置
Elasticsearch是一個(gè)基于Lucene的分布式全文搜索引擎，它在搜索、分析等方面具有出色的表現(xiàn)。Spring Boot中的Elasticsearch自動(dòng)配置為我們提供了一種快速集成Elasticsearch的方式，使我們可以在Spring Boot應(yīng)用程序中輕松地使用Elasticsearch。
本文將介紹Spring Boot中的Elasticsearch自動(dòng)配置的作用、原理和使用方法。首先，我們將了解Elasticsearch自動(dòng)配置的作用，然后深入探討它的原理和如何使用它。
## 1. Elasticsearch自動(dòng)配置的作用
使用Elasticsearch自動(dòng)配置可以幫助我們輕松地集成Elasticsearch，并提供一些默認(rèn)的配置，例如連接池、序列化方式、重試機(jī)制等，使我們可以更加專注于業(yè)務(wù)邏輯的實(shí)現(xiàn)。
Elasticsearch自動(dòng)配置為我們提供了一系列簡(jiǎn)單易用的API，用于實(shí)現(xiàn)Elasticsearch的各種操作，例如創(chuàng)建索引、添加文檔、搜索、聚合等。使用Elasticsearch自動(dòng)配置的好處是，它可以幫助我們更快速地集成Elasticsearch。
## 2. Elasticsearch自動(dòng)配置的原理
在Spring Boot中，Elasticsearch自動(dòng)配置是通過(guò)ElasticsearchAutoConfiguration類來(lái)實(shí)現(xiàn)的。該類是Spring Boot Elasticsearch Starter中的一個(gè)核心組件，用于自動(dòng)配置Elasticsearch相關(guān)的Bean。
在ElasticsearchAutoConfiguration類中，我們可以看到一系列與Elasticsearch相關(guān)的Bean的定義，例如RestHighLevelClient、ElasticsearchTemplate、ElasticsearchRestTemplate等。這些Bean的定義會(huì)被自動(dòng)裝配到Spring應(yīng)用程序中，并通過(guò)Spring IoC容器來(lái)管理和使用。
以下是ElasticsearchAutoConfiguration類的一個(gè)簡(jiǎn)化版本：
```java
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(RestHighLevelClient.class)
@AutoConfigureAfter({ ElasticsearchRestClientAutoConfiguration.class })
public class ElasticsearchAutoConfiguration {
    @Bean
    @ConditionalOnMissingBean
    public RestHighLevelClient elasticsearchClient(
            RestClientBuilderCustomizer... restClientBuilderCustomizers) throws Exception {
        return new RestHighLevelClient(
                RestClient.builder(getHostsProperties())
                        .setHttpClientConfigCallback(config -> config
                                .setDefaultCredentialsProvider(getCredentialsProvider()))
                        .setRequestConfigCallback(getRequestConfigCallback())
                        .setHttpClientConfigCallback(httpClientBuilder -> {
                            for (RestClientBuilderCustomizer customizer : restClientBuilderCustomizers) {
                                customizer.customize(httpClientBuilder);
                            }
                        }));
    }
    @Bean
    @ConditionalOnMissingBean
    public ElasticsearchRestTemplate elasticsearchRestTemplate(
            RestHighLevelClient elasticsearchClient) {
        return new ElasticsearchRestTemplate(elasticsearchClient);
    }
}

@Autowired
private ElasticsearchRestTemplate elasticsearchTemplate;
public void addBook(Book book) {
    IndexQuery indexQuery = new IndexQueryBuilder()
            .withObject(book)
            .build();
    elasticsearchTemplate.index(indexQuery);
}