JAVA 集成 ElasticSearch

目录

ElasticSearch Client

Java REST Client

Dependencies

Initialization

RequestOptions

 测试

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ElasticSearch Client

9300端口 ：TCP协议，性能较高，ES集群内部节点之间通过9300进行通讯。

• Java Transport Client （7.x 已废弃）
• Spring Data Elasticsearch

9200端口：HTTP协议，通过http请求和ES进行交互。跨语言兼容性好，易于调试。

• Java REST Client （8.x 已废弃）
• Java Client （active）
• 其他HttpClient，模拟发送http请求

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Java REST Client

谷粒商城 ES 7.4.2 仅支持 Java REST Client ，之后若有需要 再进行重构

Dependencies

<dependency><groupId>org.elasticsearch.client</groupId><artifactId>elasticsearch-rest-high-level-client</artifactId><version>7.4.2</version>
</dependency>

由于spring-boot-dependencies中<elasticsearch.version>有默认值，为避免冲突，应手动指定版本

 <properties><java.version>1.8</java.version><spring-cloud.version>Greenwich.SR3</spring-cloud.version><elasticsearch.version>7.4.2</elasticsearch.version></properties>

Initialization

• 给容器中注入一个 RestHighLevelClient 

@Configuration
public class GulimallElasticSearchConfig {@Value("${search.host.address}")private String hostName;@Beanpublic RestHighLevelClient esRestClient() {RestHighLevelClient client = new RestHighLevelClient(RestClient.builder(new HttpHost(hostName, 9200, "http")));return client;}
}

GulimallSearchApplicationTests中注入的RestHighLevelClient NotNull即可

RequestOptions

RequestOptions 主要用于：

• 共享配置：在多个请求之间共享相同的配置（如认证信息、超时设置等）。

• 简化代码：避免在每个请求中重复设置相同的参数。

• 提高性能：通过复用配置，减少不必要的对象创建和内存开销。

private static final RequestOptions COMMON_OPTIONS;
static {RequestOptions.Builder builder = RequestOptions.DEFAULT.toBuilder();builder.addHeader("Authorization", "Bearer " + TOKEN); builder.setHttpAsyncResponseConsumerFactory(           new HttpAsyncResponseConsumerFactory.HeapBufferedResponseConsumerFactory(30 * 1024 * 1024 * 1024));COMMON_OPTIONS = builder.build();
}

 测试

• Index API

source 可以以4种方式提供，即 Json字符串，map，XContentBuilder 或 键值对

    @Autowiredprivate RestHighLevelClient esRestClient;@Testpublic void indexApi() throws IOException {//索引名IndexRequest request = new IndexRequest("user");request.id("1");User user=new User();user.setName("asuka");user.setAge("18");user.setGender("女");String userJson= JSON.toJSONString(user);request.source(userJson, XContentType.JSON);//同步请求IndexResponse indexResponse = esRestClient.index(request, GulimallElasticSearchConfig.COMMON_OPTIONS);System.out.println(indexResponse);}@Dataclass User{private String name;private String age;private String gender;}

• Search API

 SearchSourceBuilder：DSL根操作，如query，aggregations，from，size等 

    @Autowiredprivate RestHighLevelClient esRestClient;@Testpublic void searchApi() throws IOException {SearchRequest searchRequest = new SearchRequest("my_bank");SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();searchSourceBuilder.query(QueryBuilders.matchQuery("address","mill"));searchSourceBuilder.size(5);//求平均薪资AggregationBuilder avgBalance= AggregationBuilders.avg("avgBalance").field("balance");searchSourceBuilder.aggregation(avgBalance);//依据年龄分组AggregationBuilder byAgeAggregationBuilder= AggregationBuilders.terms("by_age").field("age");searchSourceBuilder.aggregation(byAgeAggregationBuilder);searchRequest.source(searchSourceBuilder);SearchResponse searchResponse = esRestClient.search(searchRequest, GulimallElasticSearchConfig.COMMON_OPTIONS);System.out.println(searchResponse);SearchHits hits= searchResponse.getHits();for (SearchHit hit : hits.getHits()) {System.out.println(hit);//也可通过JSON.parseObject() 转换为 对象}//获取聚合信息Aggregations aggregations = searchResponse.getAggregations();//依据名字取出各聚合Avg balanceAvg = aggregations.get("avgBalance");System.out.println("平均薪资: " + balanceAvg.getValue());Terms byAgeAggregation = aggregations.get("by_age");for (Terms.Bucket bucket: byAgeAggregation.getBuckets()) {System.out.println("年龄 ：" +bucket.getKey()+ " 数量："+ bucket.getDocCount());}}