环境配置

创建一个maven环境，并添加如下依赖：

<dependencies>
    <dependency>
        <groupId>org.elasticsearch</groupId>
        <artifactId>elasticsearch</artifactId>
        <version>7.8.0</version>
    </dependency>
    <!-- elasticsearch 的客户端 -->
    <dependency>
        <groupId>org.elasticsearch.client</groupId>
        <artifactId>elasticsearch-rest-high-level-client</artifactId>
        <version>7.8.0</version>
    </dependency>
    <!-- elasticsearch 依赖 2.x 的 log4j -->
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
        <version>2.8.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.8.2</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.9.9</version>
    </dependency>
    <!-- junit 单元测试 -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
</dependencies>

依赖添加完成之后，连接本机的ES服务进行测试：

import java.io.IOException;
import org.apache.http.HttpHost;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;
public class HelloElasticsearch {
    public static void main(String[] args) throws IOException {
        // 创建客户端对象
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http")));
//        ...
        System.out.println(client);
        // 关闭客户端连接
        client.close();
    }
}

上述代码能正常运行完毕，则环境配置成功，可以进行后续的操作

索引操作

增加

public class CreateIndex {
    public static void main(String[] args) throws IOException {
        // 创建客户端对象
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http")));
        // 创建索引 - 请求对象
        CreateIndexRequest request = new CreateIndexRequest("user2");
        // 发送请求，获取响应
        CreateIndexResponse response = client.indices().create(request,
                RequestOptions.DEFAULT);
        boolean acknowledged = response.isAcknowledged();
        // 响应状态
        System.out.println("操作状态 = " + acknowledged);
        // 关闭客户端连接
        client.close();
    }
}

查询&删除

查询

public class SearchIndex {
    public static void main(String[] args) throws IOException {
        // 创建客户端对象
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http")));
        // 查询索引 - 请求对象
        GetIndexRequest request = new GetIndexRequest("user2");
        // 发送请求，获取响应
        GetIndexResponse response = client.indices().get(request,
                RequestOptions.DEFAULT);
        System.out.println("aliases:"+response.getAliases());
        System.out.println("mappings:"+response.getMappings());
        System.out.println("settings:"+response.getSettings());
        client.close();
    }
}

删除

public class DeleteIndex {
    public static void main(String[] args) throws IOException {
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http")));
        // 删除索引 - 请求对象
        DeleteIndexRequest request = new DeleteIndexRequest("user2");
        // 发送请求，获取响应
        AcknowledgedResponse response = client.indices().delete(request,RequestOptions.DEFAULT);
        // 操作结果
        System.out.println("操作结果 ： " + response.isAcknowledged());
        client.close();
    }
}

根据上述的代码可以猜测，Java的ES客户端中相关的API，往往都是见名知意的，比如创建索引：CreateIndexRequest，删除索引：DeleteIndexRequest，不过这仅仅只有和索引相关的操作，继续往下看

文档操作

在后续的操作中，我们并不想每次都编写连接和关闭ES的操作代码，因此对上述代码进行重构

import org.elasticsearch.client.RestHighLevelClient;
public interface ElasticsearchTask {
    void doSomething(RestHighLevelClient client) throws Exception;
}

public class ConnectElasticsearch{
    public static void connect(ElasticsearchTask task){
        // 创建客户端对象
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder(new HttpHost("localhost", 9200, "http")));
        try {
            task.doSomething(client);
            // 关闭客户端连接
            client.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

后续如果需要完成相关操作，只需要使用一个Lambda表达式即可：

public class SomeClass {
    public static void main(String[] args) {
        ConnectElasticsearch.connect(client -> {
            //do something
        });
    }
}

新增&修改

新增

import com.fasterxml.jackson.databind.ObjectMapper;
import com.lun.elasticsearch.hello.ConnectElasticsearch;
import com.lun.elasticsearch.model.User;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.common.xcontent.XContentType;
public class InsertDoc {
    public static void main(String[] args) {
        ConnectElasticsearch.connect(client -> {
            // 新增文档 - 请求对象
            IndexRequest request = new IndexRequest();
            // 设置索引及唯一性标识
            request.index("user").id("1001");
            // 创建数据对象
            User user = new User();
            user.setName("zhangsan");
            user.setAge(30);
            user.setSex("男");
            ObjectMapper objectMapper = new ObjectMapper();
            String productJson = objectMapper.writeValueAsString(user);
            // 添加文档数据，数据格式为 JSON 格式
            request.source(productJson, XContentType.JSON);
            // 客户端发送请求，获取响应对象
            IndexResponse response = client.index(request, RequestOptions.DEFAULT);
            3.打印结果信息
            System.out.println("_index:" + response.getIndex());
            System.out.println("_id:" + response.getId());
            System.out.println("_result:" + response.getResult());
        });
    }
}

修改

import com.lun.elasticsearch.hello.ConnectElasticsearch;
import org.elasticsearch.action.update.UpdateRequest;
import org.elasticsearch.action.update.UpdateResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.common.xcontent.XContentType;
public class UpdateDoc {
    public static void main(String[] args) {
        ConnectElasticsearch.connect(client -> {
            // 修改文档 - 请求对象
            UpdateRequest request = new UpdateRequest();
            // 配置修改参数
            request.index("user").id("1001");
            // 设置请求体，对数据进行修改
            request.doc(XContentType.JSON, "sex", "女");
            // 客户端发送请求，获取响应对象
            UpdateResponse response = client.update(request, RequestOptions.DEFAULT);
            System.out.println("_index:" + response.getIndex());
            System.out.println("_id:" + response.getId());
            System.out.println("_result:" + response.getResult());
        });
    }
}

查询&删除

查询

import com.lun.elasticsearch.hello.ConnectElasticsearch;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.client.RequestOptions;
public class GetDoc {
    public static void main(String[] args) {
        ConnectElasticsearch.connect(client -> {
            //1.创建请求对象
            GetRequest request = new GetRequest().index("user").id("1001");
            //2.客户端发送请求，获取响应对象
            GetResponse response = client.get(request, RequestOptions.DEFAULT);
            3.打印结果信息
            System.out.println("_index:" + response.getIndex());
            System.out.println("_type:" + response.getType());
            System.out.println("_id:" + response.getId());
            System.out.println("source:" + response.getSourceAsString());
        });
    }
}

删除

import com.lun.elasticsearch.hello.ConnectElasticsearch;
import org.elasticsearch.action.delete.DeleteRequest;
import org.elasticsearch.action.delete.DeleteResponse;
import org.elasticsearch.client.RequestOptions;
public class DeleteDoc {
    public static void main(String[] args) {
        ConnectElasticsearch.connect(client -> {
            //创建请求对象
            DeleteRequest request = new DeleteRequest().index("user").id("1001");
            //客户端发送请求，获取响应对象
            DeleteResponse response = client.delete(request, RequestOptions.DEFAULT);
            //打印信息
            System.out.println(response.toString());
        });
    }
}

到这里，结合上面所用的一些API，已经可以印证之前的猜想了：提供的API都是语义化的。删除就对应DELETE，修改就对应UPDATE

小羊的图书馆

2-Java操作ElasticSearch

环境配置

索引操作

增加

查询&删除

文档操作

新增&修改

查询&删除