Elasticsearch 入门实战(4)--Java Low Level REST Client 使用

本文主要介绍 Elasticsearch Java Low Level REST Client 的使用，相关的环境及软件信息如下：CentOS 7.6.1810、Java 1.8.0_321(客户端用)、Elasticsearch 8.2.2。

1、Java Low Level REST Client 的特点

minimal dependencies
load balancing across all available nodes
failover in case of node failures and upon specific response codes
failed connection penalization (whether a failed node is retried depends on how many consecutive times it failed; the more failed attempts the longer the client will wait before trying that same node again)
persistent connections
trace logging of requests and responses
optional automatic discovery of cluster nodes

2、引入依赖

<dependency>
    <groupId>org.elasticsearch.client</groupId>
    <artifactId>elasticsearch-rest-client</artifactId>
    <version>8.2.2</version>
</dependency>

3、使用

Java Low Level REST Client 主要工作是组装 JSON 格式的请求数据，其他都是些通用的配置；请求数据的详细说明可参考：Elasticsearch 入门实战(3)--REST API 使用。

3.1、Elasticsearch 关闭了安全认证，使用 HTTP 协议访问

@Test
public void http() {
    RestClient restClient = null;
    try {
        RestClientBuilder builder = RestClient.builder(
                new HttpHost("10.49.196.10", 9200),
                new HttpHost("10.49.196.11", 9200),
                new HttpHost("10.49.196.12", 9200));
        //设置失败监听器
        builder.setFailureListener(new RestClient.FailureListener() {
            @Override
            public void onFailure(Node node) {
                logger.info("失败:node={}", node);
            }
        });
        //设置请求头
        Header[] defaultHeaders = new Header[]{new BasicHeader("head-a", "123")};
        builder.setDefaultHeaders(defaultHeaders);

        //设置节点选择器
        builder.setNodeSelector(NodeSelector.SKIP_DEDICATED_MASTERS);

        //设置请求配置回调方法
        builder.setRequestConfigCallback(new RestClientBuilder.RequestConfigCallback() {
            @Override
            public RequestConfig.Builder customizeRequestConfig(RequestConfig.Builder builder) {
                return builder.setSocketTimeout(1000 * 5);
            }
        });

        //用户名密码
        CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
        credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials("elastic", "123456"));
        //设置HttpClient配置回调方法
        builder.setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
            @Override
            public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpAsyncClientBuilder) {
                return httpAsyncClientBuilder.setUserAgent("elasticseatch-rest-client").setDefaultCredentialsProvider(credentialsProvider);
            }
        });
        restClient = builder.build();

        //请求对象
        Request request = new Request("GET", "/poet-index/_search");
        request.addParameter("pretty", "true");
        //请求体，json数据
        String body = "{\n" +
                "  \"query\": {\n" +
                "    \"match\": {\n" +
                "      \"success\": \"思想\"\n" +
                "    }\n" +
                "  },\n" +
                "  \"from\": 0,\n" +
                "  \"size\": 10\n" +
                "}";
        request.setEntity(new NStringEntity(body, ContentType.APPLICATION_JSON));
        Response response = restClient.performRequest(request);
        logger.info("requestLine={}", response.getRequestLine());
        logger.info("host={}", response.getHost());
        logger.info("statusCode={}", response.getStatusLine().getStatusCode());
        logger.info("headers={}", response.getHeaders());
        logger.info("responseBody={}", EntityUtils.toString(response.getEntity()));
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (restClient != null) {
            try {
                restClient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

3.2、Elasticsearch 开启了安全认证，使用 HTTPS 协议访问

@Test
public void https() {
    RestClient restClient = null;
    try {
        RestClientBuilder builder = RestClient.builder(
                new HttpHost("10.49.196.10", 9200, "https"),
                new HttpHost("10.49.196.11", 9200, "https"),
                new HttpHost("10.49.196.12", 9200, "https"));
        //设置失败监听器
        builder.setFailureListener(new RestClient.FailureListener() {
            @Override
            public void onFailure(Node node) {
                logger.info("失败:node={}", node);
            }
        });
        //设置请求头
        Header[] defaultHeaders = new Header[]{new BasicHeader("head-a", "123")};
        builder.setDefaultHeaders(defaultHeaders);

        //设置节点选择器
        builder.setNodeSelector(NodeSelector.SKIP_DEDICATED_MASTERS);

        //设置请求配置回调方法
        builder.setRequestConfigCallback(new RestClientBuilder.RequestConfigCallback() {
            @Override
            public RequestConfig.Builder customizeRequestConfig(RequestConfig.Builder builder) {
                return builder.setSocketTimeout(1000 * 5);
            }
        });

        //用户名密码
        CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
        credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials("elastic", "123456"));
        //设置HttpClient配置回调方法
        builder.setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
            @Override
            public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpAsyncClientBuilder) {
                return httpAsyncClientBuilder.setUserAgent("elasticseatch-rest-client")
                        .setDefaultCredentialsProvider(credentialsProvider)
                        .setSSLContext(getSSLContext());
            }
        });
        restClient = builder.build();

        //请求对象
        Request request = new Request("GET", "/poet-index/_search");
        request.addParameter("pretty", "true");
        //请求体，json数据
        String body = "{\n" +
                "  \"query\": {\n" +
                "    \"match\": {\n" +
                "      \"success\": \"思想\"\n" +
                "    }\n" +
                "  },\n" +
                "  \"from\": 0,\n" +
                "  \"size\": 10\n" +
                "}";
        request.setEntity(new NStringEntity(body, ContentType.APPLICATION_JSON));
        Response response = restClient.performRequest(request);
        logger.info("requestLine={}", response.getRequestLine());
        logger.info("host={}", response.getHost());
        logger.info("statusCode={}", response.getStatusLine().getStatusCode());
        logger.info("headers={}", response.getHeaders());
        logger.info("responseBody={}", EntityUtils.toString(response.getEntity()));
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (restClient != null) {
            try {
                restClient.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

3.3、完整代码

package com.abc.demo.es;

import org.apache.http.Header;
import org.apache.http.HttpHost;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.CredentialsProvider;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.conn.ssl.TrustAllStrategy;
import org.apache.http.entity.ContentType;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
import org.apache.http.message.BasicHeader;
import org.apache.http.nio.entity.NStringEntity;
import org.apache.http.ssl.SSLContextBuilder;
import org.apache.http.ssl.SSLContexts;
import org.apache.http.util.EntityUtils;
import org.elasticsearch.client.*;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.net.ssl.SSLContext;
import java.io.IOException;

public class ElasticseatchRestClientCase {
    private static final Logger logger = LoggerFactory.getLogger(ElasticseatchRestClientCase.class.getName());

    @Test
    public void http() {
        RestClient restClient = null;
        try {
            RestClientBuilder builder = RestClient.builder(
                    new HttpHost("10.49.196.10", 9200),
                    new HttpHost("10.49.196.11", 9200),
                    new HttpHost("10.49.196.12", 9200));
            //设置失败监听器
            builder.setFailureListener(new RestClient.FailureListener() {
                @Override
                public void onFailure(Node node) {
                    logger.info("失败:node={}", node);
                }
            });
            //设置请求头
            Header[] defaultHeaders = new Header[]{new BasicHeader("head-a", "123")};
            builder.setDefaultHeaders(defaultHeaders);

            //设置节点选择器
            builder.setNodeSelector(NodeSelector.SKIP_DEDICATED_MASTERS);

            //设置请求配置回调方法
            builder.setRequestConfigCallback(new RestClientBuilder.RequestConfigCallback() {
                @Override
                public RequestConfig.Builder customizeRequestConfig(RequestConfig.Builder builder) {
                    return builder.setSocketTimeout(1000 * 5);
                }
            });

            //用户名密码
            CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
            credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials("elastic", "123456"));
            //设置HttpClient配置回调方法
            builder.setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
                @Override
                public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpAsyncClientBuilder) {
                    return httpAsyncClientBuilder.setUserAgent("elasticseatch-rest-client").setDefaultCredentialsProvider(credentialsProvider);
                }
            });
            restClient = builder.build();

            //请求对象
            Request request = new Request("GET", "/poet-index/_search");
            request.addParameter("pretty", "true");
            //请求体，json数据
            String body = "{\n" +
                    "  \"query\": {\n" +
                    "    \"match\": {\n" +
                    "      \"success\": \"思想\"\n" +
                    "    }\n" +
                    "  },\n" +
                    "  \"from\": 0,\n" +
                    "  \"size\": 10\n" +
                    "}";
            request.setEntity(new NStringEntity(body, ContentType.APPLICATION_JSON));
            Response response = restClient.performRequest(request);
            logger.info("requestLine={}", response.getRequestLine());
            logger.info("host={}", response.getHost());
            logger.info("statusCode={}", response.getStatusLine().getStatusCode());
            logger.info("headers={}", response.getHeaders());
            logger.info("responseBody={}", EntityUtils.toString(response.getEntity()));
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (restClient != null) {
                try {
                    restClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    @Test
    public void https() {
        RestClient restClient = null;
        try {
            RestClientBuilder builder = RestClient.builder(
                    new HttpHost("10.49.196.10", 9200, "https"),
                    new HttpHost("10.49.196.11", 9200, "https"),
                    new HttpHost("10.49.196.12", 9200, "https"));
            //设置失败监听器
            builder.setFailureListener(new RestClient.FailureListener() {
                @Override
                public void onFailure(Node node) {
                    logger.info("失败:node={}", node);
                }
            });
            //设置请求头
            Header[] defaultHeaders = new Header[]{new BasicHeader("head-a", "123")};
            builder.setDefaultHeaders(defaultHeaders);

            //设置节点选择器
            builder.setNodeSelector(NodeSelector.SKIP_DEDICATED_MASTERS);

            //设置请求配置回调方法
            builder.setRequestConfigCallback(new RestClientBuilder.RequestConfigCallback() {
                @Override
                public RequestConfig.Builder customizeRequestConfig(RequestConfig.Builder builder) {
                    return builder.setSocketTimeout(1000 * 5);
                }
            });

            //用户名密码
            CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
            credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials("elastic", "123456"));
            //设置HttpClient配置回调方法
            builder.setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
                @Override
                public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpAsyncClientBuilder) {
                    return httpAsyncClientBuilder.setUserAgent("elasticseatch-rest-client")
                            .setDefaultCredentialsProvider(credentialsProvider)
                            .setSSLContext(getSSLContext());
                }
            });
            restClient = builder.build();

            //请求对象
            Request request = new Request("GET", "/poet-index/_search");
            request.addParameter("pretty", "true");
            //请求体，json数据
            String body = "{\n" +
                    "  \"query\": {\n" +
                    "    \"match\": {\n" +
                    "      \"success\": \"思想\"\n" +
                    "    }\n" +
                    "  },\n" +
                    "  \"from\": 0,\n" +
                    "  \"size\": 10\n" +
                    "}";
            request.setEntity(new NStringEntity(body, ContentType.APPLICATION_JSON));
            Response response = restClient.performRequest(request);
            logger.info("requestLine={}", response.getRequestLine());
            logger.info("host={}", response.getHost());
            logger.info("statusCode={}", response.getStatusLine().getStatusCode());
            logger.info("headers={}", response.getHeaders());
            logger.info("responseBody={}", EntityUtils.toString(response.getEntity()));
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (restClient != null) {
                try {
                    restClient.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private SSLContext getSSLContext() {
        try {
            SSLContextBuilder bulider = SSLContexts.custom();
            bulider.loadTrustMaterial(new TrustAllStrategy());
            return bulider.build();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

}

ElasticseatchRestClientCase.java

详细的 Elasticsearch Java Low Level REST Client 使用说明，看参考官网文档：https://www.elastic.co/guide/en/elasticsearch/client/java-api-client/current/java-rest-low.html。

posted @ 2022-07-16 15:32 且行且码阅读(835) 评论(0) 编辑收藏举报

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