Elastic Search和用戶端互動，可以使用很多語言來完成搜尋，如：Java、Python、Php和Go等多種語言。由于我平常使用最多的就是Java，這裡僅基本于Java語言來示範。基于Java語言可以選擇的用戶端包括RestClient、Spring Data Elasticsearch。安裝的話可以參考《Elastic Search 8.6.2叢集安裝部署》。

4.1使用RestClient【簡單介紹】

參考文檔：

https://www.elastic.co/guide/en/elasticsearch/client/java-api-client/current/introduction.html

建立項目Spring Boot Web項目 es-demo，配置項目pom.xml檔案：

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-parent</artifactId>

</parent>

<groupId>com.study</groupId>

<version>0.0.1-SNAPSHOT</version>

<description>Elastic Search Demo project for Spring Boot</description>

<java.version>17</java.version>

</properties>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

<groupId>org.elasticsearch.client</groupId>

<artifactId>elasticsearch-rest-client</artifactId>

</dependency>

<groupId>co.elastic.clients</groupId>

<artifactId>elasticsearch-java</artifactId>

</dependency>

<groupId>org.elasticsearch</groupId>

<artifactId>elasticsearch</artifactId>

</dependency>

<groupId>org.projectlombok</groupId>

<artifactId>lombok</artifactId>

</dependency>

</dependencies>

<build>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-maven-plugin</artifactId>

</plugin>

</plugins>

</build>

</project>

在項目的application.yml檔案中配置Elastic Search連接配接屬性。host、username和password需要分别填寫協調節點服務位址（IP位址+端口号）、使用者名、密碼。

server:

port: 18000

elasticsearch:

rest:

host: 10.1.43.74:9200

username: elastic

password: hhxxttxs123BoSs465

建立EsClient類并注冊到Spring容器中。

package com.study.es.component;

import org.apache.http.HttpHost;

import org.apache.http.auth.AuthScope;

import org.apache.http.auth.UsernamePasswordCredentials;

import org.apache.http.client.CredentialsProvider;

import org.apache.http.impl.client.BasicCredentialsProvider;

import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;

import org.elasticsearch.client.RestClient;

import org.elasticsearch.client.RestClientBuilder;

import org.springframework.beans.factory.annotation.Value;

import org.springframework.context.annotation.Bean;

import org.springframework.stereotype.Component;

@Component

public class EsClient {

@Value("${elasticsearch.rest.host}")

private String hosts;

@Value("${elasticsearch.rest.username}")

private String username;

@Value("${elasticsearch.rest.password}")

private String password;

@Bean

public RestClient init() {

String[] hostParams = hosts.split(":");

int port = Integer.parseInt(hostParams[1]);

final CredentialsProvider credentialsProvider =

new BasicCredentialsProvider();

credentialsProvider.setCredentials(AuthScope.ANY,

new UsernamePasswordCredentials(username, password));

RestClientBuilder builder = RestClient.builder(

new HttpHost(hostParams[0], port))

.setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {

@Override

public HttpAsyncClientBuilder customizeHttpClient(

HttpAsyncClientBuilder httpClientBuilder) {

return httpClientBuilder

.setDefaultCredentialsProvider(credentialsProvider);

}

});

return builder.build();

}

建立文章Service類。

package com.study.es.service;

import com.study.es.component.EsClient;

import org.apache.http.util.EntityUtils;

import org.elasticsearch.client.Request;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import java.io.IOException;

@Service

public class ArticleService {

@Autowired

private EsClient esClient;

public String queryAll() throws IOException {

Request request = new Request("GET", "/article/_search");

return EntityUtils.toString(esClient.init().performRequest(request).getEntity());

}

建立文章Controller類。

package com.study.es.controller;

import com.study.es.service.ArticleService;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

import java.io.IOException;

@RestController

@RequestMapping("/article")

public class ArticleController {

@Autowired

private ArticleService articleService;

@GetMapping("/queryAll")

public String queryAll() throws IOException {

return articleService.queryAll();

}

建立啟動類。

package com.study.es;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

public class EsDemoApplication {

public static void main(String[] args) {

SpringApplication.run(EsDemoApplication.class, args);

}

通路 http://localhost:18000/article/queryAll

{

"took":4,

"timed_out":false,

"_shards":{

"total":1,

"successful":1,

"skipped":0,

"failed":0

"hits":{

"total":{

"value":1,

"relation":"eq"

"max_score":1,

"hits":[

{

"_index":"article",

"_id":"001",

"_score":1,

"_source":{

"title": "浙江...",

"brief": "【浙江麗水...",

"author": "黃甯",

"content": "【浙江麗水：住房公積...",

"readNumber": "188"

}

]

}

4.2使用Spring Boot用戶端【重點】

參考文檔 https://spring.io/projects/spring-data-elasticsearch

Spring Data Elasticsearch是Spring Boot套件中的一個元件。緻力于提供一緻的基于Spring的資料查詢和存儲程式設計模型。Spring Data Elasticsearch封裝了建立用戶端的邏輯并與服務端保持長連接配接，讓我們不必關注于網絡連接配接問題。通過對Repository接口的自動實作，可以直接通過方法名的語義實作查詢功能。還具有OR-Mapping功能，即查詢到資料後，可以将資料直接封裝到自定義的POJO中，友善後續對資料進行加工處理。

建立項目Spring Boot Web項目 es-spring-demo，配置項目pom.xml檔案：

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-data-elasticsearch</artifactId>

</dependency>

<groupId>org.projectlombok</groupId>

<artifactId>lombok</artifactId>

</dependency>

</dependencies>

在項目的application.yml檔案中配置Elastic Search連接配接屬性。當有多個協調節點時，可以設定uris的值為多個協調節點的服務位址，中間用逗号分隔。至此，當項目啟動時Spring Data Elasticsearch就會建立用戶端，然後連接配接ES服務端并與其保持長連接配接。

server:

port: 18000

spring:

elasticsearch:

rest:

uris: 10.1.43.74:9200,10.1.43.75:9200,10.1.43.76:9200

username: elastic

password: hhxxttxs123BoSs465

封裝資訊文章POJO類。

package com.study.es.pojo;

import lombok.Data;

import org.springframework.data.annotation.Id;

import org.springframework.data.elasticsearch.annotations.Document;

@Document(indexName = "article")

@Data

public class ArticlePojo {

//對應文檔ID

@Id

private String id;

//标題

private String title;

//摘要

private String brief;

//作者

private String author;

//内容

private String content;

//閱讀量

private Integer readNumber;

}

建立資訊文章Repository接口。

package com.study.es.repository;

import com.study.es.pojo.ArticlePojo;

import org.springframework.data.repository.CrudRepository;

import java.util.List;

public interface ArticleRepository extends CrudRepository<ArticlePojo, String> {

Long countArticlePojoByAuthor(String author);

List<ArticlePojo> findArticlePojoByAuthor(String author);

ArticlePojo save(ArticlePojo articlePojo);

}

建立資訊文章Service類。

package com.study.es.service;

import com.study.es.pojo.ArticlePojo;

import com.study.es.repository.ArticleRepository;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

import java.util.List;

@Service

public class ArticleService {

@Autowired

ArticleRepository articleRepository;

public Long countByAuthor(String author) {

return articleRepository.countArticlePojoByAuthor(author);

}

public List<ArticlePojo> queryByAuthor(String author) {

return articleRepository.findArticlePojoByAuthor(author);

}

public ArticlePojo saveArticle(ArticlePojo articlePojo) {

return articleRepository.save(articlePojo);

}

public void remove(String id) {

articleRepository.deleteById(id);

}

建立資訊文章Controller類。

package com.study.es.controller;

import com.study.es.pojo.ArticlePojo;

import com.study.es.service.ArticleService;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.PostMapping;

import org.springframework.web.bind.annotation.RequestMapping;

import org.springframework.web.bind.annotation.RestController;

import java.io.IOException;

import java.util.List;

import java.util.Random;

import java.util.UUID;

@RestController

@RequestMapping("/article")

public class ArticleController {

@Autowired

private ArticleService articleService;

@GetMapping("/countByAuthor")

public Long countByAuthor(String author) throws IOException {

return articleService.countByAuthor(author);

}

@GetMapping("/queryByAuthor")

public List<ArticlePojo> queryByAuthor(String author) throws IOException {

return articleService.queryByAuthor(author);

}

@PostMapping("/saveArticle")

public ArticlePojo saveArticle() throws IOException {

ArticlePojo articlePojo = new ArticlePojo();

String uuid = UUID.randomUUID().toString();

articlePojo.setTitle("标題" + uuid);

articlePojo.setBrief("摘要" + uuid);

articlePojo.setAuthor("黃甯");

articlePojo.setContent("内容" + uuid);

articlePojo.setReadNumber(new Random().nextInt(1000));

return articleService.saveArticle(articlePojo);

}

@PostMapping("/remove")

public String remove(String id){

articleService.remove(id);

return "It was removed";

}

通路 http://localhost:18000/article/queryByAuthor?author=黃甯

[

{

"id":"001",

"brief": "【浙江麗水...",

"author": "黃甯",

"content": "【浙江麗水：住房公積...",

"readNumber": "188"

}

]

建立文章Controller類。

package com.study.es;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

public class EsSpringDemoApplication {

public static void main(String[] args) {

SpringApplication.run(EsSpringDemoApplication.class, args);

}

查詢文章數量

http://localhost:18000/article/countByAuthor?author=黃甯

查詢文章清單

http://localhost:18000/article/queryByAuthor?author=黃甯

儲存文章

http://localhost:18000/article/saveArticle

删除文章

http://localhost:18000/article/remove?id=f5ubCIcBF2lPvPT87-04

#頭條創作挑戰賽#

Elastic Search 8.6.2用戶端實戰

4.1使用RestClient【簡單介紹】

4.2使用Spring Boot用戶端【重點】

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