07-SpringBoot整合ElasticSearch

9200: HTTP
9300: TCP

spring-data-elasticsearch:transport-api.jar;
springboot版本不同，ransport-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；
最终选择Elasticsearch-Rest-Client（elasticsearch-rest-high-level-client）；
https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high.html

导入依赖

这里的版本要和所安装的ELK版本匹配。

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

在spring-boot-dependencies中所依赖的ELK版本位6.8.7，需要在项目中将它改为7.4.2

    <properties>
        <elasticsearch.version>7.4.2</elasticsearch.version>
    </properties>

编写测试类

测试保存数据
https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high-document-index.html

    @Test
    public void indexData() throws IOException {
        IndexRequest indexRequest = new IndexRequest ("users");

        User user = new User();
        user.setUserName("张三");
        user.setAge(20);
        user.setGender("男");
        String jsonString = JSON.toJSONString(user);
        //设置要保存的内容
        indexRequest.source(jsonString, XContentType.JSON);
        //执行创建索引和保存数据
        IndexResponse index = client.index(indexRequest, GulimallElasticSearchConfig.COMMON_OPTIONS);
        System.out.println(index);
    }

测试获取数据
https://www.elastic.co/guide/en/elasticsearch/client/java-rest/current/java-rest-high-search.html

    @Test
    public void searchData() throws IOException {
        GetRequest getRequest = new GetRequest(
                "users",
                "_-2vAHIB0nzmLJLkxKWk");

        GetResponse getResponse = client.get(getRequest, RequestOptions.DEFAULT);
        System.out.println(getResponse);
        String index = getResponse.getIndex();
        System.out.println(index);
        String id = getResponse.getId();
        System.out.println(id);
        if (getResponse.isExists()) {
            long version = getResponse.getVersion();
            System.out.println(version);
            String sourceAsString = getResponse.getSourceAsString();
            System.out.println(sourceAsString);
            Map<String, Object> sourceAsMap = getResponse.getSourceAsMap();
            System.out.println(sourceAsMap);
            byte[] sourceAsBytes = getResponse.getSourceAsBytes();
        } else {

        }
    }

搜索address中包含mill的所有人的年龄分布以及平均年龄，平均薪资

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

java实现

    /**
     * 复杂检索:在bank中搜索address中包含mill的所有人的年龄分布以及平均年龄，平均薪资
     * @throws IOException
     */
    @Test
    public void searchData() throws IOException {
        //1. 创建检索请求
        SearchRequest searchRequest = new SearchRequest();

        //1.1）指定索引
        searchRequest.indices("bank");
        //1.2）构造检索条件
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
        sourceBuilder.query(QueryBuilders.matchQuery("address","Mill"));

        //1.2.1)按照年龄分布进行聚合
        TermsAggregationBuilder ageAgg=AggregationBuilders.terms("ageAgg").field("age").size(10);
        sourceBuilder.aggregation(ageAgg);

        //1.2.2)计算平均年龄
        AvgAggregationBuilder ageAvg = AggregationBuilders.avg("ageAvg").field("age");
        sourceBuilder.aggregation(ageAvg);
        //1.2.3)计算平均薪资
        AvgAggregationBuilder balanceAvg = AggregationBuilders.avg("balanceAvg").field("balance");
        sourceBuilder.aggregation(balanceAvg);

        System.out.println("检索条件："+sourceBuilder);
        searchRequest.source(sourceBuilder);
        //2. 执行检索
        SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
        System.out.println("检索结果："+searchResponse);

        //3. 将检索结果封装为Bean
        SearchHits hits = searchResponse.getHits();
        SearchHit[] searchHits = hits.getHits();
        for (SearchHit searchHit : searchHits) {
            String sourceAsString = searchHit.getSourceAsString();
            Account account = JSON.parseObject(sourceAsString, Account.class);
            System.out.println(account);

        }

        //4. 获取聚合信息
        Aggregations aggregations = searchResponse.getAggregations();

        Terms ageAgg1 = aggregations.get("ageAgg");

        for (Terms.Bucket bucket : ageAgg1.getBuckets()) {
            String keyAsString = bucket.getKeyAsString();
            System.out.println("年龄："+keyAsString+" ==> "+bucket.getDocCount());
        }
        Avg ageAvg1 = aggregations.get("ageAvg");
        System.out.println("平均年龄："+ageAvg1.getValue());

        Avg balanceAvg1 = aggregations.get("balanceAvg");
        System.out.println("平均薪资："+balanceAvg1.getValue());
    }  

详见代码