一：Elasticsearch-Rest-Client

1）9300：TCP
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
• 不建议9300端口操作es

2）9200：HTTP（推荐使用9200端口操作es）

• 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

结论：
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

1.新建gulimail-search微服务

2.导入es的rest-high-level-client的依赖

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

顺便将es的版本改为7.4.2

	<properties>
        <java.version>1.8</java.version>
        <elasticsearch.version>7.4.2</elasticsearch.version>
    </properties>

3.添加es的配置

1）在search包下新建config包，并且新建GulimailElasticSearchConfig配置文件

2）添加@Configuration注解
3）引入common包

		<dependency>
            <groupId>com.sysg.gulimail</groupId>
            <artifactId>gulimail-common</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>

4）在application.properties添加配置

#应用名称
spring.application.name=gulimail-search
#注册发现中心地址
spring.cloud.nacos.discovery.server-addr=127.0.0.1:8848

5）在主启动类添加@EnableDiscoveryClient注解，开启服务注册发现功能
6）编写config配置

@Configuration
public class GulimailElasticSearchConfig {
    @Bean
    public RestHighLevelClient esRestClient(){
        
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("127.0.0.1",9200,"http")));
        return client;
    }
}

给容器中注入一个RestHighLevelClient
7）在test中测试es

@SpringBootTest
@RunWith(SpringRunner.class)
public class GulimailSearchApplicationTests {
    @Autowired
    private RestHighLevelClient restHighLevelClient;
    @Test
    public void contextLoads() {
        System.out.println(restHighLevelClient);
    }
}

二：测试es的增删改查

1.配置ES安全头信息RequestOptions

作用：当所有请求访问es的时候，会带上请求头信息。此时通过RequestOptions对请求进行一些设置。给每个请求发送之前构建一些授权信息，带上token令牌

public 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();
}

2.测试存储数据到es

   /**
     * 测试存储数据到es
     */
    @Test
    public void indexData() throws IOException {
        //users-需要保存的索引名称
        IndexRequest indexRequest = new IndexRequest("users");
        //设置保存数据的主键
        indexRequest.id("1");
        //添加需要保存的数据
        User user = new User();
        user.setAge(18);
        user.setUserName("sysg");
        user.setGender("男");
          //将user对象转化为json字符串
        String toJSONString = JSON.toJSONString(user);
        indexRequest.source(toJSONString, XContentType.JSON);
        //使用客户端执行保存操作
        IndexResponse index = client.index(indexRequest, GulimailElasticSearchConfig.COMMON_OPTIONS);
        //响应数据
        System.out.println(index);
    }
    @Data
    class User{
        private String userName;
        private String gender;
        private Integer age;
    }

1）首先去kibana中查看user索引

2）在测试类执行保存方法


此时就有数据了！！！
注：更新数据也可以，当主键相同时，就会替换之前的数据！！！！

三：ES完成复杂检索

/**
     * 测试检索数据
     */
    @Test
    public void searchData() throws IOException {
        //1.创建检索请求
        SearchRequest searchRequest = new SearchRequest();
        //指定检索的索引
        searchRequest.indices("bank");
        //指定检索条件，dsl。此方法需要传入searchSourceBuilder对象
        SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();s
        //1.1)构建检索条件
        //查询条件
        sourceBuilder.query(QueryBuilders.matchQuery("address","mill"));
        //聚合条件
        //1.2)按照年龄的值进行聚合
        TermsAggregationBuilder ageAgg = AggregationBuilders.terms("ageAgg").field("age").size(10);
        sourceBuilder.aggregation(ageAgg);
        //1.3)计算平均薪资
        AvgAggregationBuilder balanceAvg = AggregationBuilders.avg("balanceAvg").field("balance");
        sourceBuilder.aggregation(balanceAvg);
        searchRequest.source(sourceBuilder);
        //2.执行检索
        SearchResponse searchResponse = client.search(searchRequest, GulimailElasticSearchConfig.COMMON_OPTIONS);
        //3.分析结果
        /*Map map = JSON.parseObject(searchResponse.toString(), Map.class);*/
        //3.1)获取到所有查询到的数据
        SearchHits hits = searchResponse.getHits();
        SearchHit[] searchHits = hits.getHits();
        for (SearchHit hit : searchHits) {
            String string = hit.getSourceAsString();
            JSONObject object = JSON.parseObject(string);
            System.out.println(object);
        }
        //3.2)获取这次检索到的分析信息
        Aggregations aggregations = searchResponse.getAggregations();
        /*for (Aggregation aggregation : aggregations.asList()) {
            String name = aggregation.getName();
            System.out.println("当前聚合名字："+name);
        }*/
        Terms ageAgg1 = aggregations.get("ageAgg");
        
    }