JAVA 集成 ElasticSearch

[ElasticSearch Client](#ElasticSearch Client)

[Java REST Client](#Java REST Client)

Dependencies

Initialization

RequestOptions

测试

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

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

XML 复制代码

<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

XML 复制代码

 <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

java 复制代码

@Configuration
public class GulimallElasticSearchConfig {
    @Value("${search.host.address}")
    private String hostName;
    @Bean
    public 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。

java 复制代码

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

java 复制代码

    @Autowired
    private RestHighLevelClient esRestClient;
    @Test
    public 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);
    }
    @Data
    class User{
        private String name;
        private String age;
        private String gender;
    }

Search API

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

java 复制代码

    @Autowired
    private RestHighLevelClient esRestClient;
    
    @Test
    public 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());
        }
    }