Elasticsearch(二) RestClient

2 May, 2020. It was a Saturday.

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Elasticsearch 客户端

Elasticsearch 提供多种不同的客户端：

1、TransportClient

这是 Elasticsearch 提供的传统客户端，官方计划 8.0 版本删除此客户端。

2、RestClient

RestClient是官方推荐使用的，它包括两种：Java Low Level REST Client 和 Java High Level REST Client。

Elasticsearch 在6.0之后提供 Java High Level REST Client，两种客户端官方更推荐使用 Java High Level REST Client，不过当前它还处于完善中，有些功能还没有。

本教程将使用 Java High Level REST Client 来执行 Elasticsearch 的相关操作。

项目准备

为了更好的进行演示 REST Client 的相关操作，创建一个 SpringBoot 项目来进行相关代码的编写。

创建好项目之后在项目中添加 Elasticsearch 的对应依赖（注意要和自己所安装的 Elasticsearch 版本相同）

<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-high-level-client</artifactId>
    <version>7.6.2</version>
</dependency>
<dependency>
    <groupId>org.elasticsearch</groupId>
    <artifactId>elasticsearch</artifactId>
    <version>7.6.2</version>
</dependency>

接下来在项目的 application.yml 中配置 Elasticsearch 的相关信息：

xedu:
  elasticsearch:
    hostlist: ${eshostlist:192.168.116.129:9200} #节点ip 多个结点中间用逗号分隔
    course:
      index: xedu_course
      source_field: id,name,grade,mt,st,charge,valid,pic,qq,price,price_old,status,studymodel,teachmode,expires,pub_ time,start_time,end_time

之后专门创建一个配置类用来创建对应的 RestClient 对象

@Configuration
public class ElasticsearchConfig {

    @Value("${xedu.elasticsearch.hostlist}")
    private String hostlist;

    // RestHighLevelClient
    @Bean
    public RestHighLevelClient restHighLevelClient(){
        //解析hostlist配置信息
        String[] split = hostlist.split(",");
        //创建HttpHost数组，其中存放es主机和端口的配置信息
        HttpHost[] httpHostArray = new HttpHost[split.length];
        for(int i=0;i<split.length;i++){
            String item = split[i];
            httpHostArray[i] = new HttpHost(item.split(":")[0], Integer.parseInt(item.split(":")[1]), "http");
        }
        //创建RestHighLevelClient客户端
        return new RestHighLevelClient(RestClient.builder(httpHostArray));
    }

    //项目主要使用RestHighLevelClient，对于低级的客户端暂时不用
    @Bean
    public RestClient restClient(){
        //解析hostlist配置信息
        String[] split = hostlist.split(",");
        //创建HttpHost数组，其中存放es主机和端口的配置信息
        HttpHost[] httpHostArray = new HttpHost[split.length];
        for(int i=0;i<split.length;i++){
            String item = split[i];
            httpHostArray[i] = new HttpHost(item.split(":")[0], Integer.parseInt(item.split(":")[1]), "http");
        }
        return RestClient.builder(httpHostArray).build();
    }

}

Elasticsearch 数据管理

创建一个单元测试类来测试如下的一些功能，在单元测试类中注入对应的 RestHighLevelClient

@SpringBootTest
@RunWith(SpringRunner.class)
public class TestElasticS {
    // 注入对应的es客户端，优先使用高等级客户端
    @Autowired
    RestHighLevelClient restHighLevelClient;
    @Autowired
    RestClient restClient;
}

创建索引库

    @Test
    public void testCreateIndex() throws IOException {
        // 创建索引请求对象
        CreateIndexRequest createIndexRequest = new CreateIndexRequest("xedu_course");
        // 设置索引参数
        createIndexRequest.settings(Settings.builder().put("number_of_shards",1).put("number_of_replicas",0));
        // 设置映射
        createIndexRequest.mapping("{\n" +
                "\t\"properties\": {\n" +
                "\t\t\"name\": { \n" +
                "\t\t\t\"type\": \"text\", \n" +
                "\t\t\t\"analyzer\":\"ik_max_word\", \n" +
                "\t\t\t\"search_analyzer\":\"ik_smart\" \n" +
                "\t\t\t\n" +
                "\t\t}, \n" +
                "\t\t\"description\": {\n" +
                "\t\t\t\"type\": \"text\",\n" +
                "\t\t\t\"analyzer\":\"ik_max_word\",\n" +
                "\t\t\t\"search_analyzer\":\"ik_smart\" \n" +
                "\t\t\t\n" +
                "\t\t}, \n" +
                "\t\t\"studymodel\": {\n" +
                "\t\t\t\"type\": \"keyword\" \n" +
                "\t\t\t\n" +
                "\t\t}, \n" +
                "\t\t\"price\": {\n" +
                "\t\t\t\"type\": \"float\" \n" +
                "\t\t\t\n" +
                "\t\t}, \n" +
                "\t\t\"timestamp\": {\n" +
                "\t\t\t\"type\": \"date\",\n" +
                "\t\t\t\"format\": \"yyyy‐MM‐dd HH:mm:ss||yyyy‐MM‐dd||epoch_millis\" \n" +
                "\t\t\t\n" +
                "\t\t}\n" +
                "\t}\n" +
                "}", XContentType.JSON);
        // 创建索引
        AcknowledgedResponse response = restHighLevelClient.indices().create(createIndexRequest,RequestOptions.DEFAULT);
        System.out.println(response.isAcknowledged());
    }

删除索引库

    @Test
    public void testDeleteIndex() throws IOException {
        // 删除索引请求对象
        DeleteIndexRequest deleteIndexRequest = new DeleteIndexRequest("xedu_course");
        // 删除索引
        AcknowledgedResponse response = restHighLevelClient.indices().delete(deleteIndexRequest,RequestOptions.DEFAULT);
        // 输出删除结果
        System.out.println(response.isAcknowledged());
    }

添加文档

    @Test
    public void testAddDoc() throws IOException {
        // 准备json数据
        Map<String, Object> jsonMap = new HashMap<>();
        jsonMap.put("name", "spring cloud实战");
        jsonMap.put("description", "本课程主要从四个章节进行讲解： 1.微服务架构入门 2.spring cloud 基础入门 3.实战Spring Boot 4.注册中心eureka。");
        jsonMap.put("studymodel", "201001");
        SimpleDateFormat dateFormat =new SimpleDateFormat("yyyy‐MM‐dd HH:mm:ss");
        jsonMap.put("timestamp", dateFormat.format(new Date()));
        jsonMap.put("price", 5.6f);
        // 索引请求对象
        IndexRequest request = new IndexRequest("xedu_course");
        // 指定索引文档内容
        request.source(jsonMap);
        // 索引响应对象
        IndexResponse response = restHighLevelClient.index(request,RequestOptions.DEFAULT);
        // 获取返回结果
        System.out.println(response.getResult());
    }

更新文档

    @Test
    public void updateDoc() throws IOException {
        // 更新请求对象
        UpdateRequest updateRequest = new UpdateRequest();
        updateRequest.index("xedu_course");
        updateRequest.type("_doc");
        updateRequest.id("3VEBbnEBoy54DVadJWzY");
        // 更新的数据文档
        updateRequest.doc(jsonBuilder()
                .startObject()
                .field("name", "spring cloud实战")
                .endObject());
        // 执行更新操作
        UpdateResponse update = restHighLevelClient.update(updateRequest,RequestOptions.DEFAULT);
        // 获取更新结果
        RestStatus status = update.status();
        System.out.println(status);

    }

删除文档

    @Test
    public void testDelDoc() throws IOException {
        //删除文档id
        String id = "3VEBbnEBoy54DVadJWzY";
        //删除索引请求对象
        DeleteRequest deleteRequest = new DeleteRequest();
        deleteRequest.index("xedu_course");
        deleteRequest.type("_doc");
        deleteRequest.id(id);
        //响应对象
        DeleteResponse deleteResponse = restHighLevelClient.delete(deleteRequest,RequestOptions.DEFAULT);
        //获取响应结果
        DocWriteResponse.Result result = deleteResponse.getResult();
        System.out.println(result);
    }