springboot 整合 elasticsearch

Java操作ElasticSearch有两种方式，一个是通过ES的9300端口使用TCP的方式操作，另一种是通过ES的9200端口使用HTTP的方式

spring-data-elasticsearch:transport-api.jar

• springboot 版本不同， transport-api.jar 不同，不能适配 es 版本
• 7.x 已经不建议使用，8 以后就要废弃

• JestClient：非官方，更新慢
• RestTemplate：模拟发 HTTP 请求，ES 很多操作需要自己封装，麻烦
• HttpClient：同上
• Elasticsearch-Rest-Client：官方 RestClient，封装了 ES 操作，API 层次分明，上手简单

综上所述，选择Elasticsearch-Rest-Client（elasticsearch-rest-high-level-client）是最优的选择

  4.0.0
  
  com.xz
  springboot-elasticsearch
  1.0-SNAPSHOT
  
    org.springframework.boot
    spring-boot-starter-parent
    2.5.2
  
  
  
    
      org.springframework.boot
      spring-boot-starter-web
    
    
    
      org.springframework.boot
      spring-boot-starter-test
    
    
    
      org.elasticsearch.client
      elasticsearch-rest-high-level-client
      7.11.1
    
  

@Configuration
public class ElasticSearchConfig {
    public static final RequestOptions COMMON_OPTIONS;

    static {
        // RequestOptions类保存了请求的部分，这些部分应该在同一个应用程序中的许多请求之间共享。
        // 创建一个singqleton实例，并在所有请求之间共享它。可以设置请求头之类的一些配置
        RequestOptions.Builder builder = RequestOptions.DEFAULT.toBuilder();
        // builder.addHeader("Authorization", "Bearer " + TOKEN);
        // builder.setHttpAsyncResponseConsumerFactory(
        //         new HttpAsyncResponseConsumerFactory
        //                 .HeapBufferedResponseConsumerFactory(30 * 1024 * 1024 *1024));
        COMMON_OPTIONS = builder.build();
    }

    //创建ES实例
    @Bean
    public RestHighLevelClient restHighLevelClient() {
        return new RestHighLevelClient(RestClient.builder(new HttpHost(
                "127.0.0.1", 9200, "http"
        )));
    }
}

测试 搜索address中包含 mill的所有人的年龄分布以及平均年龄

GET address/_search
{
  "query": {
    "match": {
      "address": "Mill"
    }
  },
  "aggs": {
    "ageAgg": {
      "terms": {
        "field": "age",
        "size": 10
      }
    },
    "ageAvg": {
      "avg": {
        "field": "age"
      }
    },
    "balanceAvg": {
      "avg": {
        "field": "balance"
      }
    }
  },
  "size": 0
}

测试代码

@SpringBootTest
public class ClientApplicationTest {
    @Autowired
    private RestHighLevelClient restHighLevelClient;
    
    @Test
    void contextLoads() throws IOException {
        //测试保存
        IndexRequest request = new IndexRequest("posts");
        request.id("1");
        String jsonString = "{" +
            ""user":"kimchy"," +
            ""postDate":"2013-01-30"," +
            ""message":"trying out Elasticsearch"" +
            "}";
        request.source(jsonString, XContentType.JSON);
        IndexResponse index =
            restHighLevelClient.index(request, ElasticSearchConfig.COMMON_OPTIONS);
        System.out.println("index-------------:" + index);
    }
    
    
    @Test
    void test() throws Exception {
        // 创建检索请求
        SearchRequest searchRequest = new SearchRequest();
        // 指定索引
        searchRequest.indices("address");
        
        // 指定DSL检索条件
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        
        // 构建检索条件 address 包含mill
        searchSourceBuilder.query(QueryBuilders.matchQuery("address", "mill"));
        
        // 按照年龄值分布进行聚合
        TermsAggregationBuilder ageAgg = AggregationBuilders.terms("ageAgg").field("age").size(10);
        searchSourceBuilder.aggregation(ageAgg);
        
        // 计算平均年龄
        AvgAggregationBuilder balanceAvg = AggregationBuilders.avg("balanceAvg").field("balance");
        searchSourceBuilder.aggregation(balanceAvg);
        
        System.out.println("检索条件: " + searchSourceBuilder.toString());
        searchRequest.source(searchSourceBuilder);
        
        // 执行检索
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, ElasticSearchConfig.COMMON_OPTIONS);
        
        // 获取查询到的记录
        SearchHits hits = searchResponse.getHits();
        SearchHit[] searchHits = hits.getHits();
        
        // 获取检索的分析信息
        Aggregations aggregations = searchResponse.getAggregations();
        for (Aggregation aggregation : aggregations.asList()) {
            System.out.println("当前聚合名: " + aggregation.getName());
        }
        Terms aggAge = aggregations.get("aggAge");
        for (Terms.Bucket bucket : aggAge.getBuckets()) {
            String keyAsString = bucket.getKeyAsString();
            System.out.println("年龄: " + keyAsString + " 岁的有 " + bucket.getDocCount() + " 人");
        }
        
        Avg balanceAvg1 = aggregations.get("balanceAvg");
        System.out.println("平均年龄: " + balanceAvg1.getValue());
        
    }
}