SpringBoot集成ElasticSearch

有多种操作ElasticSearch的客户端：

1. 9300端口+TCP连接 7.X不建议使用，8以后放弃
2. 9200端口+HTTP连接 官方推荐Rest-Client，封装了ES操作，API层次分明

配置工作----不使用SpringData的方式

1. 依赖

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

2. 配置

@Configuration
public class ElasticSearchConfig {
    @Bean
    public RestHighLevelClient esRestClient(){
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(   //如果有多个集群，则可继续配置
                        new HttpHost("139.224.48.195",9200,"http")
                )
        );
        return client;
    }
}

API操作

@SpringBootTest
public class ElasticsearcjApplicationTests {
    @Autowired
    private RestHighLevelClient client;
    
	//测试新增文档
    @Test
    public void testAddData() throws IOException {
        IndexRequest indexRequest = new IndexRequest("goods");  //参数为index的名称
        //indexRequest.id();   //自动生成文档id
        indexRequest.id("2");  //手动设置文档id
        //设置文档数据
        //1. source传入k-v键值对
        //indexRequest.source("goodName","铅笔","goodPrice",15,"goodType","学习用品");
        //2. source传入对象---最常用
        Good good = new Good("橡皮",16,"学习用品");
        String s = JSON.toJSONString(good);
        indexRequest.source(s, XContentType.JSON);
        //保存操作
        //1. 同步保存
        IndexResponse index = client.index(indexRequest, RequestOptions.DEFAULT);
        //2. 异步保存
    }

    @Data
    @AllArgsConstructor
    class Good{
        private String goodName;
        private Integer goodPrice;
        private String goodType;
    }
    
    //测试查询文档
	@Test
    public void testSearchData() throws IOException {
        //1. 创建检索请求
        SearchRequest request = new SearchRequest();
        //2. 从哪个索引检索
        request.indices("bank");
        //3. 指定DSL
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
        //3.1 构造查询条件
        sourceBuilder.query(QueryBuilders.matchQuery("address","mill"));
        //3.2 构造聚合条件   AggregationBuilders.terms(聚合名称).field(聚合字段)
        TermsAggregationBuilder ageAgg = AggregationBuilders.terms("ageAgg").field("age").size(10);//按照年龄聚合
        sourceBuilder.aggregation(ageAgg);
        AvgAggregationBuilder balanceAvg = AggregationBuilders.avg("balanceAvg").field("balance");
        sourceBuilder.aggregation(balanceAvg);
//        sourceBuilder.from(5);
//        sourceBuilder.size(5);
        request.source(sourceBuilder);
        System.out.println(sourceBuilder.toString());
        //4. 执行检索
        SearchResponse searchResponse = client.search(request, RequestOptions.DEFAULT);
        System.out.println(searchResponse.toString());
        //5. 获取Hit结果
        //Map result = JSON.parseObject(searchResponse.toString(), Map.class);  //可以转换为map，获取数据
        SearchHits hits = searchResponse.getHits();
        SearchHit[] searchHits = hits.getHits();
        for (SearchHit searchHit : searchHits) {
//          元数据：  searchHit.getIndex();  searchHit.getId();  searchHit.getScore();
//            searchHit.getSourceAsMap();  //将数据转换为map
            String sourceAsString = searchHit.getSourceAsString();
            Account account = JSON.parseObject(sourceAsString, Account.class);
            System.out.println("account="+account);
        }
        //6. 获取聚合结果
        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+"的人数为："+bucket.getDocCount());
        }
    }
}
注：如果只引入elasticsearch-rest-high-level-client，不引入elasticsearch的依赖则会报错：
  java.lang.IncompatibleClassChangeError: 
  Found interface org.elasticsearch.common.bytes.BytesReference, but class