Elasticsearch 8.7.1 with Spring

Elasticsearch是一个基于Lucene的搜索引擎，提供了分布式、多租户的全文搜索引擎功能。它可以快速地存储、搜索和分析大量数据，适用于各种类型的应用程序，如日志分析、实时搜索等。

使用Docker启动Elasticsearch & Kibana

运行命令启动Elasticsearch

docker run --name elasticsearch --net example-elastic-network -p 9200:9200 -p 9300:9300 -e "discovery.type=single-node" -t docker.elastic.co/elasticsearch/elasticsearch:8.7.1

成功后会提示

✅ Elasticsearch security features have been automatically configured!
✅ Authentication is enabled and cluster connections are encrypted.

ℹ️  Password for the elastic user (reset with `bin/elasticsearch-reset-password -u elastic`):
   这是密码

ℹ️  HTTP CA certificate SHA-256 fingerprint:
  74226f5fe0e9faefbe2b3d7f696fe1157979f164344081537679d681bd5c98a0

ℹ️  Configure Kibana to use this cluster:
• Run Kibana and click the configuration link in the terminal when Kibana starts.
• Copy the following enrollment token and paste it into Kibana in your browser (valid for the next 30 minutes):
  这是Kibana的token

ℹ️ Configure other nodes to join this cluster:
• Copy the following enrollment token and start new Elasticsearch nodes with `bin/elasticsearch --enrollment-token <token>` (valid for the next 30 minutes):
  这是配置其他节点用的token

   If you re running in Docker, copy the enrollment token and run:
     `docker run -e "ENROLLMENT_TOKEN=<token>" docker.elastic.co/elasticsearch/elasticsearch:8.7.1`

运行命令启动Kibana

docker run --name kibana --net example-elastic-network -p 5601:5601 docker.elastic.co/kibana/kibana:8.7.1

成功后会提示如下信息

...
i Kibana has not been configured.

Go to http://0.0.0.0:5601/?code=794975 to get started.
...

这个链接如果不行换成将ip地址改为localhost试试。

Kibana是Elasticsearch的可视化工具，以图表、表格和地图等形式轻松地分析和可视化Elasticsearch中存储的数据。

代码部分

在Spring Boot中使用Elasticsearch可以通过Spring Data Elasticsearch来实现。以下是一个简单的示例代码，演示如何在Spring Boot中使用Elasticsearch：

1. 添加Elasticsearch依赖
   在pom.xml文件中添加以下依赖项：

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

2. 配置application.properties
   在application.properties文件中添加以下配置项：

   # 当设置为true时，Spring会自动扫描应用程序中的@Repository注解，并创建相应的Elasticsearch存储库实例。
   spring.data.elasticsearch.repositories.enabled=true
   

3. 添加Java配置

   @Configuration
   public class ClientConfig {
       @Value("${es.hosts}")
       private String hosts;
       @Value("${es.name:elastic}")
       private String name;
       @Value("${es.password}")
       private String password;
   
       @Bean
       public ElasticsearchClient docqaElasticsearchClient() {
           final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
           credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(name, password));
           List<HttpHost> httpHosts = new ArrayList<>();
           String[] split = hosts.split(",");
           for (String s : split) {
               httpHosts.add(HttpHost.create(s));
           }
           HttpHost[] httpHosts1 = httpHosts.toArray(new HttpHost[0]);
           SSLContext sslContext;
           try {
               sslContext = readCrtFile("src/main/resources/elastic.crt");
           } catch (Exception e) {
               throw new RuntimeException(e);
           }
           RestClient client = RestClient
               .builder(httpHosts1)
               .setHttpClientConfigCallback(httpAsyncClientBuilder ->
                       httpAsyncClientBuilder.setSSLContext(sslContext).setDefaultCredentialsProvider(credentialsProvider).setKeepAliveStrategy((response, context) -> 180 * 1000))
               .build();
   
           ElasticsearchTransport transport = new RestClientTransport(client, new JacksonJsonpMapper());
           return new ElasticsearchClient(transport);
       }
   
       public static SSLContext readCrtFile(String crtFilePath) throws Exception {
           // 读取crt文件
           InputStream inputStream = new FileInputStream(crtFilePath);
           CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
           X509Certificate certificate = (X509Certificate) certificateFactory.generateCertificate(inputStream);
   
           // 创建KeyStore并将crt文件添加到KeyStore中
           KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
           keyStore.load(null, null);
           keyStore.setCertificateEntry("cert", certificate);
   
           // 创建TrustManagerFactory并初始化KeyStore
           TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
           trustManagerFactory.init(keyStore);
   
           // 创建KeyManagerFactory并初始化KeyStore
           KeyManagerFactory keyManagerFactory = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
           keyManagerFactory.init(keyStore, null);
   
           // 创建SSLContext并初始化TrustManager和KeyManager
           SSLContext sslContext = SSLContext.getInstance("TLS");
           sslContext.init(keyManagerFactory.getKeyManagers(), trustManagerFactory.getTrustManagers(), null);
   
           return sslContext;
       }
   }
   

   注意！注意！注意！
   Elastic使用了https，而本地的jdk\lib\security\cacerts中没有对应certification，会导致链接时报错，

   PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target 
   ...
   unable to find valid certification path to requested target
   

   所以要通过访问https://localhost:9200使用浏览器导出Elastic的证书。
   下面列出两种方法解决：

   • 使用命令将下载的.crt文件信息导入到本地的cacerts中： keytool -keystore path\to\jdk\cacerts -import -alias xxCert -file "path\to\xx.crt"
   • 通过上述readCrtFile方法加载crt信息。

4. 创建实体类
   创建一个Java类，用于映射Elasticsearch索引中的文档。例如：

   @Data
   @Document(indexName = "employee")
   public class Employee {
       @Id
       private String id;
       private String firstName;
       private String lastName;
       private String department;
       // Getters and setters
   }
   

5. 创建Elasticsearch存储库
   创建一个接口，扩展ElasticsearchRepository接口，用于访问Elasticsearch索引。例如：

   // ElasticsearchRepository类中有定义好的很多方法
   public interface EmployeeRepository extends ElasticsearchRepository<Employee, String> {}
   

6. 使用Elasticsearch存储库

   @RestController
   @RequestMapping("/api/employees")
   public class EmployeeController {
       // 使用自动注入的`MyDocumentRepository`访问Elasticsearch
       @Autowired
       private EmployeeRepository repository;
      
       @PostMapping
       public Employee create(@RequestBody Employee employee) {
           return repository.save(employee);
       }
       @GetMapping("/{id}")
       public Optional<Employee> findById(@PathVariable String id) {
           return repository.findById(id);
       }
   
       @GetMapping
       public Iterable<Employee> findAll() {
           return repository.findAll();
       }
   
       @PutMapping("/{id}")
       public Employee update(@PathVariable String id, @RequestBody Employee employee) {
           employee.setId(id);
           return repository.save(employee);
       }
   
       @DeleteMapping("/{id}")
       public void delete(@PathVariable String id) {
           repository.deleteById(id);
       }
   }