0.引言

在springboot整合spring data elasticsearch项目中，当索引数量较多，mapping结构较为复杂时，我们常常希望启动项目时能够自动创建索引及mapping，这样就不用再到各个环境中创建索引了

所以今天咱们就来看看如何自动创建索引

1. 思路

我们已经在实体类中声明了索引数据结构了，只需要识别有@Document注解的实体类，然后调用ElasticsearchRestTemplate的createIndex和putMapping方法即可创建索引及mapping

2. 实操

2.1 利用createIndex属性实现

如股票使用的是spring data elasticsearch包，其@Document注解中包含了一个createIndex属性，默认为true，也就是默认开启了自动创建索引的，想要关闭也可通过设置为false来实现。

2.2 利用反射实现

1、因为要调用ElasticsearchRestTemplate，所以要提前声明其bean，这个我们在之前的文章中已经讲解过，有需要的同学可以参考之前的文章

从零搭建springboot+spring data elasticsearch3.x环境

2、首先要获取所有添加@Document注解的实体类，我们需要通过Reflections类来实现

添加依赖

<dependency>
            <groupId>org.reflections</groupId>
            <artifactId>reflections</artifactId>
            <version>0.9.11</version>
</dependency>

获取方法如下，其中com.example.estest.entity是实体类的包名

Reflections f = new Reflections("com.example.estest.entity");
Set<Class<?>> classSet = f.getTypesAnnotatedWith(Document.class);

3、创建项目启动后调用的配置类

import lombok.AllArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.reflections.Reflections;
import org.springframework.context.ApplicationListener;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.event.ContextRefreshedEvent;
import org.springframework.data.elasticsearch.annotations.Document;
import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;

import java.util.Set;

/**
 * @author whx
 * @date 2022/7/2
 */
@Configuration
@Slf4j
@AllArgsConstructor
public class ElasticCreateIndexStartUp implements ApplicationListener<ContextRefreshedEvent> {

    private final ElasticsearchRestTemplate restTemplate;
    @Override
    public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent){
        log.info("[elastic]索引初始化...");
        Reflections f = new Reflections("com.example.estest.entity");
        Set<Class<?>> classSet = f.getTypesAnnotatedWith(Document.class);
        for (Class<?> clazz : classSet) {
            if(!restTemplate.indexExists(clazz)){
                restTemplate.createIndex(clazz);
                restTemplate.putMapping(clazz);
                log.info(String.format("[elastic]索引%s数据结构创建成功",clazz.getSimpleName()));
            }
        }
        log.info("[elastic]索引初始化完毕");
    }

}

需要注意以上操作基于spring-data-elasticsearch3.2.12.RELEASE，spring-data-elasticsearch4.2.x版本的配置如下

1、ElasticsearchRestTemplate bean的声明

@Configuration
@EnableElasticsearchRepositories(basePackages = "com.example.estest")
public class ElasticRestClientConfig extends AbstractElasticsearchConfiguration {

    @Value("${spring.elasticsearch.rest.uris}")
    private String url;
    @Value("${spring.elasticsearch.rest.username}")
    private String username;
    @Value("${spring.elasticsearch.rest.password}")
    private String password;

    @Override
    @Bean
    public RestHighLevelClient elasticsearchClient() {
        url = url.replace("http://","");
        String[] urlArr = url.split(",");
        HttpHost[] httpPostArr = new HttpHost[urlArr.length];
        for (int i = 0; i < urlArr.length; i++) {
            HttpHost httpHost = new HttpHost(urlArr[i].split(":")[0].trim(),
                    Integer.parseInt(urlArr[i].split(":")[1].trim()), "http");
            httpPostArr[i] = httpHost;
        }
        final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
        credentialsProvider.setCredentials(AuthScope.ANY,new UsernamePasswordCredentials(username,password));
        RestClientBuilder builder = RestClient.builder(httpPostArr)
                // 异步httpclient配置
                .setHttpClientConfigCallback(httpClientBuilder -> {
                    // 账号密码登录
                    httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
                    // httpclient连接数配置
                    httpClientBuilder.setMaxConnTotal(30);
                    httpClientBuilder.setMaxConnPerRoute(10);
                    // httpclient保活策略
                    httpClientBuilder.setKeepAliveStrategy(((response, context) -> Duration.ofMinutes(5).toMillis()));
                    return httpClientBuilder;
                });
        return new RestHighLevelClient(builder);
    }



    @Bean
    public ElasticsearchRestTemplate elasticsearchRestTemplate(RestHighLevelClient elasticsearchClient,ElasticsearchConverter elasticsearchConverter){
        return new ElasticsearchRestTemplate(elasticsearchClient,elasticsearchConverter);
    }
}

2、索引创建类

@Configuration
@Slf4j
@AllArgsConstructor
public class ElasticCreateIndexStartUp implements ApplicationListener<ContextRefreshedEvent> {

    private final ElasticsearchRestTemplate restTemplate;

    @Override
    public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent){
        log.info("[elastic]索引初始化...");
        Reflections f = new Reflections("com.example.estest.entity");
        Set<Class<?>> classSet = f.getTypesAnnotatedWith(Document.class);
        for (Class<?> clazz : classSet) {
            IndexOperations indexOperations = restTemplate.indexOps(clazz);
            if(!indexOperations.exists()){
                indexOperations.create();
                indexOperations.putMapping();
                log.info(String.format("[elastic]索引%s数据结构创建成功",clazz.getSimpleName()));
            }
        }
        log.info("[elastic]索引初始化完毕");
    }

}