ElasticSearch学习03--使用Java连接ES

1.创建项目并测试连接

1.1 新建一个spring boot的项目，在pom.xml文件中添加如下引用：

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.elasticsearch/elasticsearch -->
        <dependency>
            <groupId>org.elasticsearch</groupId>
            <artifactId>elasticsearch</artifactId>
            <version>7.3.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.elasticsearch.client/elasticsearch-rest-high-level-client -->
        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-high-level-client</artifactId>
            <version>7.3.2</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

1.2 新建一个工具类，连接ES服务

package com.demo.esdemo.utils;

import org.apache.http.HttpHost;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;

public class ESClient {
    public static RestHighLevelClient getClient() {
        //创建HttpHost
        HttpHost host = new HttpHost("localhost", 9200);


        // 创建RestClientBuilder
        RestClientBuilder builder = RestClient.builder(host);

        // 创建RestHighLevelClient
        RestHighLevelClient client = new RestHighLevelClient(builder);

        return client;
    }
}

1.3 测试连接

@Test
    void testConnect() {
        RestHighLevelClient client = ESClient.getClient();
        System.out.println("ok");
    }

1.4 运行测试

打印"ok"，测试通过。

2.使用Java操作索引

2.1 使用Java创建索引

    String index = "person";
    String type = "doc";


    @Test
    void createIndex() throws IOException {
        //settings设置
        Settings.Builder settings = Settings.builder()
                .put("number_of_shards",3)
                .put("number_of_replicas",1);


        //mappings设置
        XContentBuilder mappings = JsonXContent.contentBuilder()
            .startObject()
                .startObject("properties")
                    .startObject("name")
                        .field("type","text")
                    .endObject()
                    .startObject("age")
                        .field("type","integer")
                    .endObject()
                    .startObject("birthday")
                        .field("type","date")
                        .field("format","yyyy-MM-dd")
                    .endObject()
                .endObject()
            .endObject();

        //将settings和mappings封装到Resquest对象中
        CreateIndexRequest request = new CreateIndexRequest(index)
                .settings(settings)
                .mapping(mappings);

        //通过client连接es，并创建索引
        RestHighLevelClient client = ESClient.getClient();
        CreateIndexResponse response = client.indices().create(request, RequestOptions.DEFAULT);

        //输出
        System.out.println(response);
    }

2.2 检查索引是否存在

String index = "person";
    String type = "doc";

    @Test
    void exists() throws IOException {
        //准备request对象
        GetIndexRequest request = new GetIndexRequest(index);

        //通过client连接es
        RestHighLevelClient client = ESClient.getClient();
        boolean exists = client.indices().exists(request, RequestOptions.DEFAULT);

        //输出
        System.out.println(exists);
    }

2.3 删除索引

    String index = "person";
    String type = "doc";

    @Test
    void delete() throws IOException {
        //准备request对象

        DeleteIndexRequest request = new DeleteIndexRequest(index);

        //通过client连接es
        RestHighLevelClient client = ESClient.getClient();
        AcknowledgedResponse delete = client.indices().delete(request, RequestOptions.DEFAULT);

        //输出
        System.out.println(delete.isAcknowledged());
    }

3.使用Java操作文档

3.1 添加文档

    String index = "person";
    String type = "doc";

    @Test
    void createDoc() throws IOException {
        //准备一个json数据
        Person person = new Person(1,"张三",18,new Date());
        ObjectMapper mapper = new ObjectMapper();
        String json = mapper.writeValueAsString(person);

        //准备request对象
        IndexRequest request = new IndexRequest(index,"_doc","1");
        request.source(json, XContentType.JSON);

        //通过client对象连接es
        RestHighLevelClient client = ESClient.getClient();
        IndexResponse response = client.index(request, RequestOptions.DEFAULT);

        //输出
        System.out.println(response.getResult());
    }

3.2 修改与删除文档

    String index = "person";
    String type = "doc";

    @Test
    void updateDoc() throws IOException {
        //创建一个map，指定需要修改的内容
        Map<String,Object> doc = new HashMap<>();
        doc.put("name","李四");

        //request对象
        UpdateRequest request = new UpdateRequest(index,"1");
        request.doc(doc);

        //连接es
        RestHighLevelClient client = ESClient.getClient();
        UpdateResponse update = client.update(request, RequestOptions.DEFAULT);

        //输出
        System.out.println(update.getResult());
    }

3.3 删除文档

    String index = "person";
    String type = "doc";
    
    @Test
    void deleteDoc() throws IOException {
        //request对象
        DeleteRequest request = new DeleteRequest(index,"1");

        //client执行
        RestHighLevelClient client = ESClient.getClient();
        DeleteResponse delete = client.delete(request, RequestOptions.DEFAULT);

        //输出
        System.out.println(delete.getResult());
    }

4.批量操作文档

4.1 批量添加文档

    String index = "person";
    String type = "doc";

    @Test
    void bulkCreateDoc() throws IOException {
        //准备一个json数据
        Person person1 = new Person(1,"张三",18,new Date());
        Person person2 = new Person(2,"李四",20,new Date());
        Person person3 = new Person(3,"王五",24,new Date());
        ObjectMapper mapper = new ObjectMapper();
        String json1 = mapper.writeValueAsString(person1);
        String json2 = mapper.writeValueAsString(person2);
        String json3 = mapper.writeValueAsString(person3);

        //准备request对象
        BulkRequest request = new BulkRequest();
        request.add(new IndexRequest(index,"_doc",person1.getId().toString()).source(json1,XContentType.JSON));
        request.add(new IndexRequest(index,"_doc",person2.getId().toString()).source(json2,XContentType.JSON));
        request.add(new IndexRequest(index,"_doc",person3.getId().toString()).source(json3,XContentType.JSON));


        //通过client对象连接es
        RestHighLevelClient client = ESClient.getClient();
        BulkResponse response = client.bulk(request, RequestOptions.DEFAULT);

        //输出
        System.out.println(response);
    }

4.2 批量删除文档

    String index = "person";
    String type = "_doc";

    @Test
    void buldDeleteDoc() throws IOException {
        BulkRequest request = new BulkRequest();
        request.add(new DeleteRequest(index,type,"1"));
        request.add(new DeleteRequest(index,type,"2"));
        request.add(new DeleteRequest(index,type,"3"));

        RestHighLevelClient client = ESClient.getClient();
        BulkResponse response = client.bulk(request, RequestOptions.DEFAULT);

        System.out.println(response);
    }

5.查询文档

5.1 使用term方式查询

    String index = "book";
    String type = "_doc";

    @Test
    void termQuery() throws IOException {
        //request
        SearchRequest request = new SearchRequest(index);
        //request.searchType(type);

        //指定查询条件
        SearchSourceBuilder builder = new SearchSourceBuilder();
        builder.from(0);
        builder.size(5);
        builder.query(QueryBuilders.termQuery("name","机器"));

        request.source(builder);

        RestHighLevelClient client = ESClient.getClient();
        SearchResponse search = client.search(request, RequestOptions.DEFAULT);

        for(SearchHit hit:search.getHits().getHits()){
            Map<String,Object> result = hit.getSourceAsMap();
            System.out.println(result);
        }
    }

查询结果是是正确的。