Elasticsearch 7.16.x Java 开发之项目搭建_co.elastic.clients.elasticsearch-java 封装

Elasticsearch 7.16.x Java 开发之项目搭建

一、背景概述

公司升级 ES 库版本，从 5.x 升至 7.16，然后就有了今天的故事…

二、Java Rest Client

• Java Low Level Rest Client：低级别客户端，允许通过 HTTP 请求与 ES 集群进行通信，封装度低但无视 ES 版本。
• Java High Level Rest Client：高级别客户端，基于低级别客户端封装。

Java Low Level Rest Client

官网地址：Java Low Level REST Client

相关依赖

<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-client</artifactId>
    <version>7.16.2</version>
</dependency>
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代码示例

public RestClient getClient() {
    // ES 连接信息
    HttpHost[] hosts = {new HttpHost("localhost", 9200, "http")};
    // 如果有密码，设置身份认证
    final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
    credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials("elasticsearch", "123456"));
    // 创建 LOW-LEVEL-CLIENT 连接
    return RestClient.builder(hosts)
            .setRequestConfigCallback(requestConfigBuilder -> requestConfigBuilder
                    // 统一设置 REQUEST 请求，也可以分别设置每个 REQUEST 请求，见方法 getSpecialRequest()
                    .setConnectTimeout(6000)
                    .setSocketTimeout(6000)
            )
            .setHttpClientConfigCallback(httpClientBuilder -> httpClientBuilder
                    // 设置身份认证
                    .setDefaultCredentialsProvider(credentialsProvider)
                    // 设置线程数
                    .setDefaultIOReactorConfig(IOReactorConfig.custom().setIoThreadCount(6).build())
            )
            .build();
}

/**
 * 单独设置 REQUEST 请求
 */
public Request getSpecialRequest(Request request) {
    RequestConfig requestConfig = RequestConfig.custom()
            .setConnectTimeout(6000)
            .setSocketTimeout(6000).build();
    RequestOptions options = RequestOptions.DEFAULT.toBuilder().setRequestConfig(requestConfig).build();
    request.setOptions(options);
    return request;
}
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测试一下~

/**
 * @param myIndex 索引库库名
 */
public void test(String myIndex) {
    RestClient lowLevelClient = getClient();
    Request request = new Request("POST", "/" + myIndex + "/_search");
    request.setEntity(new StringEntity("{'query':{'match':{'title':'ES'}}}", StandardCharsets.UTF_8));
    Response response = lowLevelClient.performRequest(request);
    HttpEntity entity = response.getEntity();
    String result = EntityUtils.toString(entity, StandardCharsets.UTF_8);
    return JSON.parseObject(result);
}
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Java High Level Rest Client

官网地址：Elasticsearch Java API Client

相关依赖

<dependency>
    <groupId>co.elastic.clients</groupId>
    <artifactId>elasticsearch-java</artifactId>
    <version>7.16.2</version>
</dependency>
<!-- 这个依赖官方文档给的是 2.12.3，但我 Class/Method Not Found -->
<!-- 大胆猜测一下，官方写错了~ -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.11.2</version>
</dependency>
<!-- 大胆猜测一下，官方写错了~ -->
<!-- 这个依赖官方文档给的是 2.12.3，但我 Class/Method Not Found -->
<!-- 这个依赖官方文档没写，Class/Method Not Found 的同志可以加上这个试试 -->
<dependency>
    <groupId>jakarta.json</groupId>
    <artifactId>jakarta.json-api</artifactId>
    <version>2.0.1</version>
</dependency>
<!-- 这个依赖官方文档没写，Class/Method Not Found 的同志可以加上这个试试  -->
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另外，如果项目本身是 Spring Boot 项目，需额外注意，Spring 是否声明了其他版本的 ES，Spring Data也是整了 ES 的，别问我为什么不用，问就是那个版本太低不好使。我在这个坑里躺了 N 久…闻者伤心见者流泪…

<properties>
    <elasticsearch.version>7.16.2</elasticsearch.version>
</properties>
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代码示例

public ElasticsearchClient getClient() {
    // ES 连接信息
    HttpHost[] hosts = {new HttpHost("localhost", 9200, "http")};
    // 如果有密码，设置身份认证
    final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
    credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials("elastic", "123456"));
    // 创建 LOW-LEVEL-CLIENT 连接
    RestClient lowLevelClient = RestClient.builder(hosts)
            // 设置身份认证
            .setHttpClientConfigCallback(httpClientBuilder -> httpClientBuilder
                    .setDefaultCredentialsProvider(credentialsProvider))
            .build();
    ElasticsearchTransport transport = new RestClientTransport(lowLevelClient, new JacksonJsonpMapper());
    ElasticsearchClient client = new ElasticsearchClient(transport);
    return client;
}
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测试一下~

/**
 * @param myIndex 索引库库名
 */
public void test(String myIndex) {
    ElasticsearchClient highLevelClient = getClient();
    SearchResponse<MyEntity> search = highLevelClient.search(searchRequest -> searchRequest
                    .index(myIndex)
                    .query(query -> query.term(term -> term.field("title").value(value -> value.stringValue("ES")))),
            MyEntity.class);
    for (Hit<MyEntity> hit : search.hits().hits()) {
        log.info(hit.source().toString());
    }
}
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到此结束~~~