Elasticsearch Rest Client实战

原创

bellen

发布于 2018-08-27 20:08:36

2.2K0

发布于 2018-08-27 20:08:36

文章被收录于专栏：腾讯云Elasticsearch Service腾讯云Elasticsearch Service

Elasticsearch Rest Client实战

Elasticsearch官方推荐使用Java REST客户端连接集群并进行数据操作。Java REST client有两种：一种是Java Low Level REST Client，使用该客户端需要将http请求的body手动拼成json格式，http响应也必须将返回的json数据手动封装成对象；另外一种是Java High Level REST Client, 该客户端基于低级客户端实现，提供API解决低级客户端需要手动转换数据格式的问题。

Java High Level REST Client

使用Java High Level REST Client访问集群，示例步骤与代码如下：

1 添加maven依赖

<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-high-level-client</artifactId>
    <version>5.6.11</version>
</dependency>

2 实战代码

import org.apache.http.HttpHost;
import org.apache.log4j.Logger;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.action.DocWriteResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.index.IndexResponse;
import org.elasticsearch.action.get.GetRequest;
import org.elasticsearch.action.get.GetResponse;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.rest.RestStatus;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;
/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: bellengao, bellengao@tencent.com
 * Date: 2018-08-27
 * Time: 下午6:00
 */
public class TestHighLevelRestClient {
    private static Logger logger = Logger.getLogger(TestHighLevelRestClient.class);

    public  static void main(String[]args){
        // 初始化RestClient, hostName和port填写集群的内网vip地址与端口
        RestClientBuilder builder = RestClient.builder(new HttpHost("localhost", 9200, "http"));
        // 设置超时时间
        builder.setMaxRetryTimeoutMillis(10000);
        RestClient restClient = builder.build();
        // 由Low Level Client构造High Level Client
        RestHighLevelClient client = new RestHighLevelClient(restClient);

        // 索引文档
        Map<String, Object> jsonMap = new HashMap<String, Object>();
        jsonMap.put("user", "bellen");
        jsonMap.put("name", new Date());
        jsonMap.put("message", "trying out Elasticsearch");
        IndexRequest indexRequest = new IndexRequest("posts", "doc", "1")
                .source(jsonMap);

        try {
            // 获取响应结果
            IndexResponse indexResponse = client.index(indexRequest);
            String index = indexResponse.getIndex();
            String type = indexResponse.getType();
            String id = indexResponse.getId();
            long version = indexResponse.getVersion();

            if (indexResponse.getResult() == DocWriteResponse.Result.CREATED) {
                logger.info("doc indexed, index: "+ index +", type:"+ type +",id:"+ id+",version:"+version);
            } else if (indexResponse.getResult() == DocWriteResponse.Result.UPDATED) {
                logger.info("doc updated, index: "+ index +", type:"+ type +",id:"+ id+",version:"+version);
            }
        }catch(ElasticsearchException e) {
            if (e.status() == RestStatus.CONFLICT) {
                logger.error("version conflict");

            }
        }catch(Exception e){
            logger.error("execute index api failed, "+ e.toString());
        }


        // 查询文档
        GetRequest getRequest = new GetRequest(
                "posts",
                "doc",
                "1");
        try {
            // 获取响应结果
            GetResponse getResponse = client.get(getRequest);
            String index = getResponse.getIndex();
            String type = getResponse.getType();
            String id = getResponse.getId();
            if (getResponse.isExists()) {
                long version = getResponse.getVersion();
                String sourceAsString = getResponse.getSourceAsString();
                logger.info("get doc, index: "+ index +", type:"+ type +",id:"+ id+",version:"+version +", source:"+ sourceAsString);
            }
        }catch (ElasticsearchException e) {
            if (e.status() == RestStatus.NOT_FOUND) {
                logger.warn("doc not found");
            }
        }
        catch(Exception e){
            logger.error("execute get api failed, "+ e.toString());
        }

        // 关闭客户端
        try {
            restClient.close();
        }catch (Exception e){
            logger.error("close rest client exception:"+ e.toString());
        }
    }
}

注意事项

client版本需要与ES集群版本保持一致，否则可能会出现兼容性问题
Java High Level Client构建于Java Low Level Client之上，两种client都是基于http协议连接ES集群，Java High Level Client可提供的API种类随着版本升级会越来越多，如果当前版本的Java High Level Client提供的API不满足需求，可以通过升级ES集群版本和Client版本解决。
使用TCP协议连接ES集群的Transport Client官方已经不再维护，建议使用使用HTTP协议连接集群的Java High Level Client或者Java Low Level Client。可以参考官方文档由TransportClient迁移至Java High Level Client：https://www.elastic.co/guide/en/elasticsearch/client/java-rest/5.6/java-rest-high-level-migration.html

原创声明：本文系作者授权腾讯云开发者社区发表，未经许可，不得转载。

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