Elasticsearch 学习之Spring Boot使用 Java Rest client

Elasticsearch 学习之Spring Boot使用 Java Rest client

Rest client

Elasticsearch Java Rest client 分成两部分：

• Java Low Level REST Client
  • 官方低级别 es 客户端，使用 http 协议与 Elastiicsearch 集群通信，与所有 es 版本兼容。
• Java High level REST Client
  • 官方高级别 es 客户端，基于低级别的客户端，它会暴露 API 特定的方法。

官网地址

Java High Level REST Client

本文基于Elasticsearch 6.5.4版本操作

导入maven依赖

		<dependency>
			<groupId>org.elasticsearch.client</groupId>
			<artifactId>elasticsearch-rest-high-level-client</artifactId>
			<version>6.5.4</version>
		</dependency>

防止某些api不兼容，导入对应的客户端版本

初始化连接对象

@Configuration
public class ElasticsearchClientConfig {


    @Bean(autowire = Autowire.BY_NAME, name = "restHighLevelClient")
    public RestHighLevelClient restClient() {
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(
                        new HttpHost("localhost", 9200, "http")));
        return client;
    }

    //main方法测试连接是否成功
    public static void main(String[] args) throws IOException{
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(
                        new HttpHost("localhost", 9200, "http")));
        Map<String, Object> jsonMap = new HashMap<>();
        jsonMap.put("user", "kimchy");
        jsonMap.put("postDate", new Date());
        jsonMap.put("message", "trying out Elasticsearch");
        IndexRequest indexRequest = new IndexRequest("posts")
                .index("test")
                .type("test")
                .id("1").source(jsonMap);
            IndexResponse indexResponse = client.index(indexRequest, RequestOptions.DEFAULT);
            client.close();
    }
}

注入连接对象

 @Resource(name="restHighLevelClient")//通过指定对应的名称注入
 private RestHighLevelClient highLevelClient;

使用 RestHighLevelClient

RestHighLevelClient提供了三种传入数据的格式操作对应的API，接下来我们基于创建索引展示

创建索引

1. 使用json字符串调用API

 @Test
public void createIndex1() throws IOException {
    String jsonString = "{" +
        "\"user\":\"kimchy\"," +
        "\"postDate\":\"2013-01-30\"," +
        "\"message\":\"trying out Elasticsearch\"" +
        "}";
    IndexRequest indexRequest = new IndexRequest("posts")
        .index("test")
        .type("test")
        .id("1").source(jsonString,XContentType.JSON);
    IndexResponse indexResponse = highLevelClient.index(indexRequest, RequestOptions.DEFAULT);
    }

1. 使用map对象调用API

@Test
public void createIndex() throws IOException {
    Map<String, Object> jsonMap = new HashMap<>();
    jsonMap.put("user", "kimchy");
    jsonMap.put("postDate", new Date());
    jsonMap.put("message", "trying out Elasticsearch");
    IndexRequest indexRequest = new IndexRequest("posts")
        .index("test")
        .type("test")
        .id("1").source(jsonMap);

    IndexResponse indexResponse = highLevelClient.index(indexRequest, RequestOptions.DEFAULT);
}

1. 使用XContentBuilder操作API

@Test
public void createIndex2() throws IOException {
    XContentBuilder builder = XContentFactory.jsonBuilder();
    builder.startObject();
    {
        builder.field("user", "kimchy");
        builder.timeField("postDate", new Date());
        builder.field("message", "trying out Elasticsearch");
    }
    builder.endObject();
    IndexRequest indexRequest = new IndexRequest("posts")
        .index("test")
        .type("test")
        .id("1").source(builder);
    IndexResponse indexResponse = highLevelClient.index(indexRequest, RequestOptions.DEFAULT);//
}

1. 关闭连接

@After
public void after() throws IOException {
    highLevelClient.close();
}

以上方式我们可以根据自己的实际情况选择一种即可，更多详细信息可以参考官网提供的Api，非常详细

官网API

本文后面全部使用json字符串的方式操作

新增文档

 @Test
public void addTest() {
    IndexRequest indexRequest = new IndexRequest("megacorp", "employee");
    MegacorpBean megacorpBean = new MegacorpBean();
    megacorpBean.setDesc("中国产小型无人机的“对手”来了，俄微型拦截导弹便宜量又多");
    megacorpBean.setName("戴小小南");
    megacorpBean.setDate(new Date());
    megacorpBean.setContent("数据库管理");
    String jsonStr = JSONObject.toJSONString(megacorpBean);
    indexRequest.source(jsonStr, XContentType.JSON);
    try {
        highLevelClient.index(indexRequest,RequestOptions.DEFAULT);
    } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace();
    }
}

MegacorpBean对象

@Data
public class MegacorpBean {
    private String content;
    private String desc;
    private String message;
    private String name;
    private Date date;
}

更新文档

@Test
public void updateDoc() {
    UpdateRequest updateRequest = new UpdateRequest("megacorp", "employee", "1");
    MegacorpBean megacorpBean = new MegacorpBean();
    megacorpBean.setName("戴小二小南");
    String jsonStr = JSONObject.toJSONString(megacorpBean);
    updateRequest.doc(jsonStr, XContentType.JSON);
    try {
        highLevelClient.update(updateRequest,RequestOptions.DEFAULT);
    } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace();
    }
}

索引文档

@Test
public void matchQuery() throws Exception {
    SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
    SearchRequest searchRequest = new SearchRequest();
    QueryBuilder matchQueryBuilder = QueryBuilders.matchQuery("desc", "数据库管理")
        .fuzziness(Fuzziness.AUTO)
        .prefixLength(3)
        .maxExpansions(10);
    searchSourceBuilder.query(matchQueryBuilder);
    searchRequest.source(searchSourceBuilder);
    SearchResponse searchResponse = highLevelClient.search(searchRequest, RequestOptions.DEFAULT);
    System.out.println(searchResponse);
}

本文主要介绍基于Spring Boot使用Java High Level REST Client，支持的三种数据格式，以及展示一些基本的api相关操作，更多api 操作还是要读者自己去查阅官方提供的api文档。