JAVA 集成 ElasticSearch

目录

ElasticSearch 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

<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;
    @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。

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

    @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 

    @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());
        }
    }