java與es8實戰之四：SpringBoot應用中操作es8(無安全檢查)

歡迎存取我的GitHub

這裡分類和彙總了欣宸的全部原創(含配套原始碼)：https://github.com/zq2599/blog_demos

本篇概覽

• 本篇是《java與es8實戰》系列的第四篇，系列文章寫到現在，連個HelloWorld都沒執行起來，實在說不過去了...
• 因此，本篇總體目標明確：實戰在SpringBoot應用中操作elasticsearch8
• 為了降低難度，本篇部署的elasticsearch8未設定安全檢查，無需證書、賬號、密碼，只要連線到es的IP和埠就能執行操作
• 總體目標可以拆解為兩個子任務

1. 在SpringBoot中連線elasticsearch8
2. 在SpringBoot中使用elasticsearch8官方的Java API Client

• 接下來直接開始

部署elasticsearch叢集(無安全檢查)

• 關於快速部署elasticsearch叢集(無安全檢查)，可以參考《docker-compose快速部署elasticsearch-8.x叢集+kibana》

Java應用連線elasticsearch的核心套路

• 不論是直連，還是帶安全檢查的連線，亦或是與SpringBoot的整合使之更方便易用，都緊緊圍繞著一個不變的核心套路，該套路由兩部分組成，掌握了它們就能在各種條件下成功連線es

1. 首先，是builder pattern，連線es有關的程式碼，各種物件都是其builder物件的build方法建立的，建議您提前閱讀《java與es8實戰之一》一文，看完後，滿屏的builder程式碼可以從醜變成美...
2. 其次，就是java應用能向es發請求的關鍵：ElasticsearchClient物件，該物件的建立是有套路的，如下圖，先建立RestClient，再基於RestClient建立ElasticsearchTransport，最後基於ElasticsearchTransport建立ElasticsearchClient，這是個固定的套路，咱們後面的操作都是基於此的，可能會加一點東西，但不會改變流程和圖中的物件
   

• 準備完畢，開始寫程式碼

新建子工程

• 為了便於管理依賴庫版本和原始碼，《java與es8實戰》系列的所有程式碼都以子工程的形式存放在父工程elasticsearch-tutorials中

• 《java與es8實戰之二：實戰前的準備工作》一文說明了建立父工程的詳細過程

• 在父工程elasticsearch-tutorials中新建名為basic-crud的子工程，其pom.xml內容如下

<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <!-- 請改為自己專案的parent座標 -->
    <parent>
        <artifactId>elasticsearch-tutorials</artifactId>
        <groupId>com.bolingcavalry</groupId>
        <version>1.0-SNAPSHOT</version>
        <relativePath>../pom.xml</relativePath>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <!-- 請改為自己專案的artifactId -->
    <artifactId>basic-crud</artifactId>
    <packaging>jar</packaging>
    <!-- 請改為自己專案的name -->
    <name>basic-crud</name>
    <url>https://github.com/zq2599</url>

    <!--不用spring-boot-starter-parent作為parent時的設定-->
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>

                <version>${springboot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>

        <!-- 不加這個，configuration類中，IDEA總會新增一些提示 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

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

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>

            <!-- exclude junit 4 -->
            <exclusions>
                <exclusion>
                    <groupId>junit</groupId>
                    <artifactId>junit</artifactId>
                </exclusion>
            </exclusions>

        </dependency>

        <!-- junit 5 -->
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-engine</artifactId>
            <scope>test</scope>
        </dependency>

        <!-- elasticsearch引入依賴  start -->
        <dependency>
            <groupId>co.elastic.clients</groupId>
            <artifactId>elasticsearch-java</artifactId>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
        </dependency>

        <!-- 使用spring boot Maven外掛時需要新增該依賴 -->
        <dependency>
            <groupId>jakarta.json</groupId>
            <artifactId>jakarta.json-api</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- 需要此外掛，在執行mvn test命令時才會執行單元測試 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>3.0.0-M4</version>
                <configuration>
                    <skipTests>false</skipTests>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>

        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.*</include>
                </includes>
            </resource>
        </resources>
    </build>
</project>

編碼：組態檔

• 先準備好組態檔application.yml，內容如下，很簡單，只有es的地址資訊

elasticsearch:
  # 多個IP逗號隔開
  hosts: 127.0.0.1:9200

編碼：設定類

• 首先把啟動類寫好，平平無奇的啟動類BasicCrudApplication.java

@SpringBootApplication
public class BasicCrudApplication {
    public static void main(String[] args) {
        SpringApplication.run(BasicCrudApplication.class, args);
    }
}

• 然後是設定類ClientConfig.java，這是本篇的關鍵，操作ES所需的ElasticsearchClient範例如何建立，ES的IP地址如何傳入，全部寫在這裡了

package com.bolingcavalry.basic.config;

import co.elastic.clients.elasticsearch.ElasticsearchAsyncClient;
import co.elastic.clients.elasticsearch.ElasticsearchClient;
import co.elastic.clients.json.jackson.JacksonJsonpMapper;
import co.elastic.clients.transport.rest_client.RestClientTransport;
import lombok.Setter;
import org.apache.http.HttpHost;
import org.elasticsearch.client.RestClient;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.util.StringUtils;

@ConfigurationProperties(prefix = "elasticsearch") //設定的字首
@Configuration
public class ClientConfig {

    @Setter
    private String hosts;

    /**
     * 解析設定的字串，轉為HttpHost物件陣列
     * @return
     */
    private HttpHost[] toHttpHost() {
        if (!StringUtils.hasLength(hosts)) {
            throw new RuntimeException("invalid elasticsearch configuration");
        }

        String[] hostArray = hosts.split(",");
        HttpHost[] httpHosts = new HttpHost[hostArray.length];
        HttpHost httpHost;
        for (int i = 0; i < hostArray.length; i++) {
            String[] strings = hostArray[i].split(":");
            httpHost = new HttpHost(strings[0], Integer.parseInt(strings[1]), "http");
            httpHosts[i] = httpHost;
        }

        return httpHosts;
    }

    @Bean
    public ElasticsearchClient elasticsearchClient() {
        HttpHost[] httpHosts = toHttpHost();
        RestClient restClient = RestClient.builder(httpHosts).build();
        RestClientTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        return new ElasticsearchClient(transport);
    }

    @Bean
    public ElasticsearchAsyncClient elasticsearchAsyncClient() {
        HttpHost[] httpHosts = toHttpHost();
        RestClient restClient = RestClient.builder(httpHosts).build();
        RestClientTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        return new ElasticsearchAsyncClient(transport);
    }
}

• 從上面的程式碼可以看出，設定類已經向Spring容器註冊了ElasticsearchClient範例，後面的業務都可以使用此範例來操作ES

編碼：服務類

• 本篇只是為了演示SpringBoot應用如何連線和操作ES，還不會深入ES操作的細節，因此只對索引做一些基本操作即可

• 先寫一個介面IndexService.java，裡面定義了多個索引操作的方法

package com.bolingcavalry.basic.service;

import co.elastic.clients.elasticsearch._types.mapping.TypeMapping;
import co.elastic.clients.elasticsearch.indices.IndexSettings;
import co.elastic.clients.util.ObjectBuilder;

import java.io.IOException;
import java.util.function.Function;

public interface IndexService {

    /**
     * 新建指定名稱的索引
     * @param name
     * @throws IOException
     */
    void addIndex(String name) throws IOException;

    /**
     * 檢查指定名稱的索引是否存在
     * @param name
     * @return
     * @throws IOException
     */
    boolean indexExists(String name) throws IOException;

    /**
     * 刪除指定索引
     * @param name
     * @throws IOException
     */
    void delIndex(String name) throws IOException;

    /**
     * 建立索引，指定setting和mapping
     * @param name 索引名稱
     * @param settingFn 索引引數
     * @param mappingFn 索引結構
     * @throws IOException
     */
    void create(String name,
                Function<IndexSettings.Builder, ObjectBuilder<IndexSettings>> settingFn,
                Function<TypeMapping.Builder, ObjectBuilder<TypeMapping>> mappingFn) throws IOException;
}

• 然後介面的實現，可見所有操作都是在呼叫ElasticsearchClient範例的API

package com.bolingcavalry.basic.service.impl;

import co.elastic.clients.elasticsearch.ElasticsearchClient;
import co.elastic.clients.elasticsearch._types.mapping.TypeMapping;
import co.elastic.clients.elasticsearch.indices.IndexSettings;
import co.elastic.clients.util.ObjectBuilder;
import com.bolingcavalry.basic.service.IndexService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Service;

import java.io.IOException;
import java.util.function.Function;

@Service
public class IndexServiceImpl implements IndexService {

    @Autowired
    private ElasticsearchClient elasticsearchClient;

    @Override
    public void addIndex(String name) throws IOException {
        ApplicationContext applicationContext;
        elasticsearchClient.indices().create(c -> c.index(name));
    }

    @Override
    public boolean indexExists(String name) throws IOException {
        ApplicationContext a;
        return elasticsearchClient.indices().exists(b -> b.index(name)).value();
    }

    @Override
    public void delIndex(String name) throws IOException {
        elasticsearchClient.indices().delete(c -> c.index(name));
    }

    @Override
    public void create(String name,
                       Function<IndexSettings.Builder, ObjectBuilder<IndexSettings>> settingFn,
                       Function<TypeMapping.Builder, ObjectBuilder<TypeMapping>> mappingFn) throws IOException {
       elasticsearchClient
               .indices()
               .create(c -> c
                       .index(name)
                       .settings(settingFn)
                       .mappings(mappingFn)
               );
    }
}

• 以上就是本篇的功能程式碼了，連線ES在其上進行索引相關操作

編碼：單元測試

• 為了驗證上述程式碼是否生效，接下來寫一個單元測試類IndexServiceTest.java，可以重點關注createIndex方法，裡面演示了Builder pattern構建引數的詳細步驟

package com.bolingcavalry.basic.service;

import co.elastic.clients.elasticsearch._types.mapping.Property;
import co.elastic.clients.elasticsearch._types.mapping.TypeMapping;
import co.elastic.clients.elasticsearch.indices.IndexSettings;
import co.elastic.clients.util.ObjectBuilder;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.function.Function;

@SpringBootTest
class IndexServiceTest {

    @Autowired
    IndexService indexService;

    @Test
    void addIndex() throws Exception {
        String indexName = "test_index";

        Assertions.assertFalse(indexService.indexExists(indexName));
        indexService.addIndex(indexName);
        Assertions.assertTrue(indexService.indexExists(indexName));
        indexService.delIndex(indexName);
        Assertions.assertFalse(indexService.indexExists(indexName));
    }

    @Test
    void indexExists() throws Exception {
        indexService.indexExists("a");
    }

    @Test
    void createIndex() throws Exception {
        // 索引名
        String indexName = "product002";

        // 構建setting時，builder用到的lambda
        Function<IndexSettings.Builder, ObjectBuilder<IndexSettings>> settingFn = sBuilder -> sBuilder
                .index(iBuilder -> iBuilder
                        // 三個分片
                        .numberOfShards("3")
                        // 一個副本
                        .numberOfReplicas("1")
                );

        // 新的索引有三個欄位，每個欄位都有自己的property，這裡依次建立
        Property keywordProperty = Property.of(pBuilder -> pBuilder.keyword(kBuilder -> kBuilder.ignoreAbove(256)));
        Property textProperty = Property.of(pBuilder -> pBuilder.text(tBuilder -> tBuilder));
        Property integerProperty = Property.of(pBuilder -> pBuilder.integer(iBuilder -> iBuilder));

        // // 構建mapping時，builder用到的lambda
        Function<TypeMapping.Builder, ObjectBuilder<TypeMapping>> mappingFn = mBuilder -> mBuilder
                .properties("name", keywordProperty)
                .properties("description", textProperty)
                .properties("price", integerProperty);

        // 建立索引，並且指定了setting和mapping
        indexService.create(indexName, settingFn, mappingFn);
    }
}

• 確保不做安全檢查的ES叢集執行正常，再執行單元測試，如下圖，順利通過，證明所有對ES的操作都符合預期
  
• 再用eshead觀察product002索引的情況，如下圖，三個分片，一個副本，與程式碼中設定的一致
  
• 至此最簡單的連線和操作ES實戰已經完成，希望本篇能給您一些參考，助您順利完成基本操作

是不是執行緒安全的

• 官方迴應：https://discuss.elastic.co/t/is-elasticsearch-client-is-thread-safe/151745
• 有人在問這個問題，es團隊的成員Simon Willnauer的回答是：java的client肯定是執行緒安全的，golang的不清楚
  
• 對我來說，有他這話就夠了，至於golang的嘛，在本文就不討論了

原始碼下載

• 本篇實戰的完整原始碼可在GitHub下載到，地址和連結資訊如下表所示(https://github.com/zq2599/blog_demos)

• 這個git專案中有多個資料夾，本次實戰的原始碼在elasticsearch-tutorials資料夾下，如下圖紅框
  
• elasticsearch-tutorials是個父工程，裡面有多個module，本篇實戰的module是basic-crud，如下圖紅框
  

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