Elasticsearch是一個(gè)基于Lucene的搜索引擎，提供了分布式、多租戶的全文搜索引擎功能。它可以快速地存儲(chǔ)、搜索和分析大量數(shù)據(jù)，適用于各種類型的應(yīng)用程序，如日志分析、實(shí)時(shí)搜索等。

使用Docker啟動(dòng)Elasticsearch & Kibana

運(yùn)行命令啟動(dòng)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

成功后會(huì)提示

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

??  Password for the elastic user (reset with `bin/elasticsearch-reset-password -u elastic`):
   這是密碼

??  HTTP CA certificate SHA-256 fingerprint:
  74226f5fe0e9faefbe2b3d7f696fe1157979f164344081537679d681bd5c98a0

??  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):
  這是Kibana的token

?? 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):
  這是配置其他節(jié)點(diǎn)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`

運(yùn)行命令啟動(dòng)Kibana

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

成功后會(huì)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.
...

這個(gè)鏈接如果不行換成將ip地址改為localhost試試。

Kibana是Elasticsearch的可視化工具，以圖表、表格和地圖等形式輕松地分析和可視化Elasticsearch中存儲(chǔ)的數(shù)據(jù)。

代碼部分

在Spring Boot中使用Elasticsearch可以通過(guò)Spring Data Elasticsearch來(lái)實(shí)現(xiàn)。以下是一個(gè)簡(jiǎn)單的示例代碼，演示如何在Spring Boot中使用Elasticsearch：

1. 添加Elasticsearch依賴
   在pom.xml文件中添加以下依賴項(xiàng)：

   <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項(xiàng)：

   # 當(dāng)設(shè)置為true時(shí)，Spring會(huì)自動(dòng)掃描應(yīng)用程序中的@Repository注解，并創(chuàng)建相應(yīng)的Elasticsearch存儲(chǔ)庫(kù)實(shí)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 {
           // 讀取crt文件
           InputStream inputStream = new FileInputStream(crtFilePath);
           CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
           X509Certificate certificate = (X509Certificate) certificateFactory.generateCertificate(inputStream);
   
           // 創(chuàng)建KeyStore并將crt文件添加到KeyStore中
           KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType());
           keyStore.load(null, null);
           keyStore.setCertificateEntry("cert", certificate);
   
           // 創(chuàng)建TrustManagerFactory并初始化KeyStore
           TrustManagerFactory trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
           trustManagerFactory.init(keyStore);
   
           // 創(chuàng)建KeyManagerFactory并初始化KeyStore
           KeyManagerFactory keyManagerFactory = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm());
           keyManagerFactory.init(keyStore, null);
   
           // 創(chuàng)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中沒(méi)有對(duì)應(yīng)certification，會(huì)導(dǎo)致鏈接時(shí)報(bào)錯(cuò)，

   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
   

   所以要通過(guò)訪問(wèn)https://localhost:9200使用瀏覽器導(dǎo)出Elastic的證書。
   下面列出兩種方法解決：

   • 使用命令將下載的.crt文件信息導(dǎo)入到本地的cacerts中： keytool -keystore path\to\jdk\cacerts -import -alias xxCert -file "path\to\xx.crt"
   • 通過(guò)上述readCrtFile方法加載crt信息。

4. 創(chuàng)建實(shí)體類
   創(chuàng)建一個(gè)Java類，用于映射Elasticsearch索引中的文檔。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. 創(chuàng)建Elasticsearch存儲(chǔ)庫(kù)
   創(chuàng)建一個(gè)接口，擴(kuò)展ElasticsearchRepository接口，用于訪問(wèn)Elasticsearch索引。例如：

   // ElasticsearchRepository類中有定義好的很多方法
   public interface EmployeeRepository extends ElasticsearchRepository<Employee, String> {}
   

6. 使用Elasticsearch存儲(chǔ)庫(kù)

   @RestController
   @RequestMapping("/api/employees")
   public class EmployeeController {
       // 使用自動(dòng)注入的`MyDocumentRepository`訪問(wèn)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);
       }
   }