通过应用程序连接集群

注意事项

为确保兼容性，建议客户端使用的 Java、Python 或 Go 语言版本与ES集群底层运行时的版本保持一致。

示例代码

Java

此处以ES 8.17.0为例，介绍如何通过Java连接ES集群。

1. 安装Java JDK，JDK版本为1.8及以上。

2. 配置pom依赖。

   重要

   请将version设置为正确的ES版本号，只有当version设置正确时才能拉取相关依赖，本示例ES版本为8.17.0。

   <dependency>
       <groupId>co.elastic.clients</groupId>
       <artifactId>elasticsearch-java</artifactId>
       <version>8.17.0</version>
   </dependency>
   <dependency>
       <groupId>com.fasterxml.jackson.core</groupId>
       <artifactId>jackson-databind</artifactId>
       <version>2.12.3</version>
   </dependency>

3. 连接ES集群并创建名为hr_test的索引。

   需配置YML参数，开启自动创建索引：action.auto_create_index: true。

   package org.example;
   import co.elastic.clients.elasticsearch.ElasticsearchClient;
   import co.elastic.clients.elasticsearch.cat.IndicesResponse;
   import co.elastic.clients.elasticsearch.indices.*;
   import co.elastic.clients.json.jackson.JacksonJsonpMapper;
   import co.elastic.clients.transport.ElasticsearchTransport;
   import co.elastic.clients.transport.rest_client.RestClientTransport;
   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.*;
   import java.io.IOException;
   public class RestClientTest {
       public static void main(String[] args) {
           // 阿里云Elasticsearch集群需要basic auth验证。
           final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
           //访问用户名和密码为您创建阿里云Elasticsearch实例时设置的用户名和密码，也是Kibana控制台的登录用户名和密码。
           credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials("{UserName}", "{YourPassword}"));
           // 通过builder创建rest client，配置http client的HttpClientConfigCallback。
           // 单击所创建的Elasticsearch实例ID，在基本信息页面获取公网地址，即为ES集群地址。
           RestClient restClient = RestClient.builder(new HttpHost("{YourEsHost}", 9200, "http"))
                   .setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
                       @Override
                       public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {
                           return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
                       }
                   }).build();
   
           // 使用 Jackson 映射器创建传输
           ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
           // 创建 API 客户端
           ElasticsearchClient elasticsearchClient = new ElasticsearchClient(transport);
           // 创建了一个名为 "foo" 的别名，并将其设置为写入别名 (write index)，这意味着所有写入操作（例如索引、更新、删除文档）将自动路由到这个别名所对应的索引上。
           try {
               //创建索引
               CreateIndexResponse indexRequest = elasticsearchClient.indices().create(createIndexBuilder -> createIndexBuilder
                       .index("hr_test")
                       .aliases("foo", aliasBuilder -> aliasBuilder
                               .isWriteIndex(true)
                       )
               );
               //检查“indexRequest”请求的操作是否已被Elasticsearch集群确认
               boolean acknowledged = indexRequest.acknowledged();
               System.out.println("Index document successfully! " + acknowledged);
   
               //查看所有索引信息（health status index uuid pri rep）
               IndicesResponse indicesResponse = elasticsearchClient.cat().indices();
               indicesResponse.valueBody().forEach(info -> System.out.println(info.health() + "\t"+  info.status() + "\t" + info.index() + "\t" + info.uuid() +"\t" + info.pri() + "\t" + info.rep()));
   
   
               transport.close();
               restClient.close();
           } catch (IOException ioException) {
               // 异常处理。
           }
       }
   }
   

   成功执行后返回以下信息：

   

Python

# 安装指定版本的依赖
pip install elasticsearch==8.17.0
from elasticsearch import Elasticsearch

# 连接集群
es = Elasticsearch(
    hosts=['http://<YourEsHost>:9200'],
    basic_auth=('<UserName>', '<YourPassword>'),
)
# 获取并打印集群信息
res = es.info() 
print(res)

# 安装指定版本的依赖
pip install elasticsearch==7.10.0

# 代码示例
from elasticsearch import Elasticsearch

# 连接集群
es = Elasticsearch(
    hosts=['http://<YourEsHost>:9200'],
    basic_auth=('<UserName>', '<YourPassword>'),
)

res = es.info()
print(res)

# 安装指定版本的依赖
pip install elasticsearch==6.8.2

from elasticsearch import Elasticsearch

# 连接集群
es = Elasticsearch(
    hosts=['http://<YourEsHost>:9200'],
    basic_auth=('<UserName>', '<YourPassword>'),
)
res = es.info()
print(res)

# 安装指定版本的依赖
pip install elasticsearch==5.5.3

from elasticsearch import Elasticsearch

# 连接集群
es = Elasticsearch(
    hosts=['http://<YourEsHost>:9200'],
    basic_auth=('<UserName>', '<YourPassword>'),
)
res = es.info()
print(res)

Go

以下以ES 8.x版本为例介绍如何通过Go连接ES，更多Go API Client的使用特性，请参见Elasticsearch Go Client。

go get github.com/elastic/go-elasticsearch/v8
package main

import (
	"github.com/elastic/go-elasticsearch/v8"
	"log"
)

func main() {
	cfg := elasticsearch.Config{
		Addresses: []string{
			"http://<YourEsHost>:9200",
		},
		Username: "<UserName>",
		Password: "<YourPassword>",
	}

	es, err := elasticsearch.NewClient(cfg)
	if err != nil {
		log.Fatalf("Error creating the client: %s", err)
	}

	res, err := es.Info()
	if err != nil {
		log.Fatalf("Error getting response: %s", err)
	}

	defer res.Body.Close()
	log.Println(res)
}

# 连接集群
es = Elasticsearch(
    hosts=['https://<YourEsHost>:9200'],
    basic_auth=('<UserName>', '<YourPassword>'),
)