通过Rest Low Level Client接入集群

High Level Client是在Low Level Client基础上进行封装的，如果High Level Client中的方法调用（例如.search，.bulk）不能满足使用需求，或存在兼容性问题，可以选择使用Low Level Client方式，甚至可以使用“HighLevelClient.getLowLevelClient()”方式直接获取Low Level Client。使用Low Level Client发送请求时需要自己定义请求结构，使用上更为灵活，能满足所有Elasticsearch支持的请求格式，例如GET、POST、DELETE、HEAD等。

本文介绍通过Rest Low Level Client访问CSS集群的配置说明。Rest Low Level Client接入集群有3种方式，每一种方式又分为直接创建Rest Client（即Rest Low Level Client）和通过创建High Level Client再调用getLowLevelClient()获取Low Level Client。

通过Rest Low Level Client连接非安全集群：适用于非安全模式的集群
通过Rest Low Level Client连接安全集群（不使用安全证书）：适用于安全模式+HTTP协议的集群、安全模式+HTTPS协议的集群（忽略证书）
通过Rest Low Level Client连接安全集群（使用安全证书）：适用于安全模式+HTTPS协议的集群

注意事项

建议Rest Low Level Client的版本和Elasticsearch的版本保持一致，例如需要访问的ES集群版本是7.6.2，则使用的Rest Low Level Client客户端版本建议也是7.6.2。

准备工作

CSS集群处于可用状态。
确保运行Java代码的服务器与CSS集群的网络是互通的。
确认服务器已安装JDK1.8，JDK1.8官网下载地址：http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html。

通过Maven方式引入apache版本。代码示例以7.6.2版本为例。

其中7.6.2为Elasticsearch Java客户端的版本号。

<dependency>
	<groupId>org.elasticsearch.client</groupId>
	<artifactId>elasticsearch-rest-client</artifactId>
	<version>7.6.2</version>
</dependency>
<dependency>
    <groupId>org.elasticsearch</groupId>
    <artifactId>elasticsearch</artifactId>
    <version>7.6.2</version>
</dependency>

通过Rest Low Level Client连接非安全集群

方式一：直接创建Rest Low Level Client

      
       
         
         
           import org.apache.http.HttpHost;
import org.elasticsearch.client.Request;
import org.elasticsearch.client.Response;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

public class Main {

    public static void main(String[] args) throws IOException {
        List<String> host = Arrays.asList("xxx.xxx.xxx.xxx", "xxx.xxx.xxx.xxx");
        RestClientBuilder builder = RestClient.builder(constructHttpHosts(host, 9200, "http"));
        /**
         * 创建Rest Low Level Client。
         */
        RestClient lowLevelClient = builder.build();
        /**
         * 查询“test”索引是否存在。当索引存在时返回200，不存在时返回404。
         */
        Request request = new Request("HEAD", "/test");
        Response response = lowLevelClient.performRequest(request);
        System.out.println(response.getStatusLine().getStatusCode());
        lowLevelClient.close();
    }

    /**
     * constructHttpHosts函数转换host集群节点ip列表。
     */
    public static HttpHost[] constructHttpHosts(List<String> host, int port, String protocol) {
        return host.stream().map(p -> new HttpHost(p, port, protocol)).toArray(HttpHost[]::new);
    }
}

          

        

      
     

方式二：创建High Level Client再调用getLowLevelClient()获取Low Level Client

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

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

public class Main {

    public static void main(String[] args) throws IOException {
        List<String> host = Arrays.asList("xxx.xxx.xxx.xxx", "xxx.xxx.xxx.xxx");
        RestClientBuilder builder = RestClient.builder(constructHttpHosts(host, 9200, "http"));
        final RestHighLevelClient restHighLevelClient = new RestHighLevelClient(builder);
        /**
         * 创建High Level Client再调用getLowLevelClient()获取Low Level Client，即client创建仅下面这一行代码存在差别。
         */
        final RestClient lowLevelClient = restHighLevelClient.getLowLevelClient();
        /**
         * 查询“test”索引是否存在。当索引存在时返回200，不存在时返回404。
         */
        Request request = new Request("HEAD", "/test");
        Response response = lowLevelClient.performRequest(request);
        System.out.println(response.getStatusLine().getStatusCode());
        lowLevelClient.close();
    }

    /**
     * constructHttpHosts函数转换host集群节点ip列表。
     */
    public static HttpHost[] constructHttpHosts(List<String> host, int port, String protocol) {
        return host.stream().map(p -> new HttpHost(p, port, protocol)).toArray(HttpHost[]::new);
    }
}

          

        

      
     

其中，host为集群各个节点的IP地址列表，当存在多个IP地址时，中间用“,”隔开；test为查询的索引名称。

通过Rest Low Level Client连接安全集群（不使用安全证书）

方式一：直接创建Rest Low Level Client

      
       
         
         
           import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.CredentialsProvider;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.client.DefaultConnectionKeepAliveStrategy;
import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
import org.apache.http.nio.conn.ssl.SSLIOSessionStrategy;
import org.apache.http.protocol.HttpContext;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.client.Request;
import org.elasticsearch.client.Response;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.common.Nullable;

import java.io.IOException;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.TimeUnit;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.TrustManager;import javax.net.ssl.X509TrustManager;

public class Main {

    /**
     * 创建客户端的类，定义create函数用于创建客户端。
     */
    public static RestClient create(List<String> host, int port, String protocol, int connectTimeout, int connectionRequestTimeout, int socketTimeout,  String username, String password) throws IOException {
        final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
        credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(username, password));
        SSLContext sc = null;
        try {
            sc = SSLContext.getInstance("SSL");
            sc.init(null, trustAllCerts, new SecureRandom());
        } catch (KeyManagementException | NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        SSLIOSessionStrategy sessionStrategy = new SSLIOSessionStrategy(sc, new NullHostNameVerifier());
        SecuredHttpClientConfigCallback httpClientConfigCallback = new SecuredHttpClientConfigCallback(sessionStrategy,
            credentialsProvider);

        RestClientBuilder builder = RestClient.builder(constructHttpHosts(host, port, protocol))
            .setRequestConfigCallback(requestConfig -> requestConfig.setConnectTimeout(connectTimeout)
                .setConnectionRequestTimeout(connectionRequestTimeout)
                .setSocketTimeout(socketTimeout))
            .setHttpClientConfigCallback(httpClientConfigCallback);
        final RestClient client = builder.build();
        logger.info("es rest client build success {} ", client);
        return client;
    }

    /**
     * constructHttpHosts函数转换host集群节点ip列表。
     */
    public static HttpHost[] constructHttpHosts(List<String> host, int port, String protocol) {
        return host.stream().map(p -> new HttpHost(p, port, protocol)).toArray(HttpHost[]::new);
    }

    /**
     * trustAllCerts忽略证书配置。
     */
    public static TrustManager[] trustAllCerts = new TrustManager[] {
        new X509TrustManager() {
            @Override
            public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
            }

            @Override
            public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
            }

            @Override
            public X509Certificate[] getAcceptedIssuers() {
                return null;
            }
        }
    };

    /**
     * CustomConnectionKeepAliveStrategy函数设置连接的保活时间，主要应对大量短连接的情况和数据请求不高的场景。
     */
    public static class CustomConnectionKeepAliveStrategy extends DefaultConnectionKeepAliveStrategy {
        public static final CustomConnectionKeepAliveStrategy INSTANCE = new CustomConnectionKeepAliveStrategy();

        private CustomConnectionKeepAliveStrategy() {
            super();
        }

        /**
         * 最大keep alive的时间（分钟）
         * 这里默认为10分钟，可以根据实际情况设置。可以观察客户端机器状态为TIME_WAIT的TCP连接数，如果太多，可以增大此值。
         */
        private final long MAX_KEEP_ALIVE_MINUTES = 10;

        @Override
        public long getKeepAliveDuration(HttpResponse response, HttpContext context) {
            long keepAliveDuration = super.getKeepAliveDuration(response, context);
            // <0 为无限期keepalive
            // 将无限期替换成一个默认的时间
            if (keepAliveDuration < 0) {
                return TimeUnit.MINUTES.toMillis(MAX_KEEP_ALIVE_MINUTES);
            }
            return keepAliveDuration;
        }
    }

    private static final Logger logger = LogManager.getLogger(Main.class);

    static class SecuredHttpClientConfigCallback implements RestClientBuilder.HttpClientConfigCallback {
        @Nullable
        private final CredentialsProvider credentialsProvider;
        /**
         * The {@link SSLIOSessionStrategy} for all requests to enable SSL / TLS encryption.
         */
        private final SSLIOSessionStrategy sslStrategy;
        /**
         * Create a new {@link SecuredHttpClientConfigCallback}.
         *
         * @param credentialsProvider The credential provider, if a username/password have been supplied
         * @param sslStrategy         The SSL strategy, if SSL / TLS have been supplied
         * @throws NullPointerException if {@code sslStrategy} is {@code null}
         */
        SecuredHttpClientConfigCallback(final SSLIOSessionStrategy sslStrategy,
            @Nullable final CredentialsProvider credentialsProvider) {
            this.sslStrategy = Objects.requireNonNull(sslStrategy);
            this.credentialsProvider = credentialsProvider;
        }
        /**
         * Get the {@link CredentialsProvider} that will be added to the HTTP client.
         *
         * @return Can be {@code null}.
         */
        @Nullable
        CredentialsProvider getCredentialsProvider() {
            return credentialsProvider;
        }
        /**
         * Get the {@link SSLIOSessionStrategy} that will be added to the HTTP client.
         *
         * @return Never {@code null}.
         */
        SSLIOSessionStrategy getSSLStrategy() {
            return sslStrategy;
        }
        /**
         * Sets the {@linkplain HttpAsyncClientBuilder#setDefaultCredentialsProvider(CredentialsProvider) credential provider},
         *
         * @param httpClientBuilder The client to configure.
         * @return Always {@code httpClientBuilder}.
         */
        @Override
        public HttpAsyncClientBuilder customizeHttpClient(final HttpAsyncClientBuilder httpClientBuilder) {
            // enable SSL / TLS
            httpClientBuilder.setSSLStrategy(sslStrategy);
            // enable user authentication
            if (credentialsProvider != null) {
                httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
            }
            return httpClientBuilder;
        }
    }

    public static class NullHostNameVerifier implements HostnameVerifier {
        @Override
        public boolean verify(String arg0, SSLSession arg1) {
            return true;
        }
    }

    /**
     * main函数参考如下，调用create函数创建Rest Low Level Client客户端，查询“test”索引是否存在。
     */
    public static void main(String[] args) throws IOException {
        RestClient lowLevelClient = create(Arrays.asList("xxx.xxx.xxx.xxx", "xxx.xxx.xxx.xxx"), 9200, "http", 1000, 1000, 1000, "username", "password");
        Request request = new Request("HEAD", "/test");
        Response response = lowLevelClient.performRequest(request);
        System.out.println(response.getStatusLine().getStatusCode());
        lowLevelClient.close();
    }
}

          

        

      
     

方式二：创建High Level Client再调用getLowLevelClient()获取Low Level Client

      
       
         
         
           import org.apache.http.HttpHost;
import org.apache.http.HttpResponse;
import org.apache.http.auth.AuthScope;
import org.apache.http.auth.UsernamePasswordCredentials;
import org.apache.http.client.CredentialsProvider;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.client.DefaultConnectionKeepAliveStrategy;
import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
import org.apache.http.nio.conn.ssl.SSLIOSessionStrategy;
import org.apache.http.protocol.HttpContext;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.client.Request;
import org.elasticsearch.client.Response;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.common.Nullable;

import java.io.IOException;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.TimeUnit;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.TrustManager;import javax.net.ssl.X509TrustManager;

import org.elasticsearch.client.RestHighLevelClient;

public class Main13 {

    /**
     * 创建客户端的类，定义create函数用于创建客户端。
     */
    public static RestHighLevelClient create(List<String> host, int port, String protocol, int connectTimeout, int connectionRequestTimeout, int socketTimeout,  String username, String password) throws IOException {

        final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
        credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(username, password));
        SSLContext sc = null;
        try {
            sc = SSLContext.getInstance("SSL");
            sc.init(null, trustAllCerts, new SecureRandom());
        } catch (KeyManagementException | NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        SSLIOSessionStrategy sessionStrategy = new SSLIOSessionStrategy(sc, new NullHostNameVerifier());
        SecuredHttpClientConfigCallback httpClientConfigCallback = new SecuredHttpClientConfigCallback(sessionStrategy,
            credentialsProvider);

        RestClientBuilder builder = RestClient.builder(constructHttpHosts(host, port, protocol))
            .setRequestConfigCallback(requestConfig -> requestConfig.setConnectTimeout(connectTimeout)
                .setConnectionRequestTimeout(connectionRequestTimeout)
                .setSocketTimeout(socketTimeout))
            .setHttpClientConfigCallback(httpClientConfigCallback);
        final RestHighLevelClient client = new RestHighLevelClient(builder);
        logger.info("es rest client build success {} ", client);
        return client;
    }

    /**
     * constructHttpHosts函数转换host集群节点ip列表。
     */
    public static HttpHost[] constructHttpHosts(List<String> host, int port, String protocol) {
        return host.stream().map(p -> new HttpHost(p, port, protocol)).toArray(HttpHost[]::new);
    }

    /**
     * trustAllCerts忽略证书配置。
     */
    public static TrustManager[] trustAllCerts = new TrustManager[] {
        new X509TrustManager() {
            @Override
            public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {
            }

            @Override
            public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {
            }

            @Override
            public X509Certificate[] getAcceptedIssuers() {
                return null;
            }
        }
    };

    /**
     * CustomConnectionKeepAliveStrategy函数设置连接的保活时间，主要应对大量短连接的情况和数据请求不高的场景。
     */
    public static class CustomConnectionKeepAliveStrategy extends DefaultConnectionKeepAliveStrategy {
        public static final CustomConnectionKeepAliveStrategy INSTANCE = new CustomConnectionKeepAliveStrategy();

        private CustomConnectionKeepAliveStrategy() {
            super();
        }

        /**
         * 最大keep alive的时间（分钟）
         * 这里默认为10分钟，可以根据实际情况设置。可以观察客户端机器状态为TIME_WAIT的TCP连接数，如果太多，可以增大此值。
         */
        private final long MAX_KEEP_ALIVE_MINUTES = 10;

        @Override
        public long getKeepAliveDuration(HttpResponse response, HttpContext context) {
            long keepAliveDuration = super.getKeepAliveDuration(response, context);
            // <0 为无限期keepalive
            // 将无限期替换成一个默认的时间
            if (keepAliveDuration < 0) {
                return TimeUnit.MINUTES.toMillis(MAX_KEEP_ALIVE_MINUTES);
            }
            return keepAliveDuration;
        }
    }

    private static final Logger logger = LogManager.getLogger(Main.class);

    static class SecuredHttpClientConfigCallback implements RestClientBuilder.HttpClientConfigCallback {
        @Nullable
        private final CredentialsProvider credentialsProvider;
        /**
         * The {@link SSLIOSessionStrategy} for all requests to enable SSL / TLS encryption.
         */
        private final SSLIOSessionStrategy sslStrategy;
        /**
         * Create a new {@link SecuredHttpClientConfigCallback}.
         *
         * @param credentialsProvider The credential provider, if a username/password have been supplied
         * @param sslStrategy         The SSL strategy, if SSL / TLS have been supplied
         * @throws NullPointerException if {@code sslStrategy} is {@code null}
         */
        SecuredHttpClientConfigCallback(final SSLIOSessionStrategy sslStrategy,
            @Nullable final CredentialsProvider credentialsProvider) {
            this.sslStrategy = Objects.requireNonNull(sslStrategy);
            this.credentialsProvider = credentialsProvider;
        }
        /**
         * Get the {@link CredentialsProvider} that will be added to the HTTP client.
         *
         * @return Can be {@code null}.
         */
        @Nullable
        CredentialsProvider getCredentialsProvider() {
            return credentialsProvider;
        }
        /**
         * Get the {@link SSLIOSessionStrategy} that will be added to the HTTP client.
         *
         * @return Never {@code null}.
         */
        SSLIOSessionStrategy getSSLStrategy() {
            return sslStrategy;
        }
        /**
         * Sets the {@linkplain HttpAsyncClientBuilder#setDefaultCredentialsProvider(CredentialsProvider) credential provider},
         *
         * @param httpClientBuilder The client to configure.
         * @return Always {@code httpClientBuilder}.
         */
        @Override
        public HttpAsyncClientBuilder customizeHttpClient(final HttpAsyncClientBuilder httpClientBuilder) {
            // enable SSL / TLS
            httpClientBuilder.setSSLStrategy(sslStrategy);
            // enable user authentication
            if (credentialsProvider != null) {
                httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
            }
            return httpClientBuilder;
        }
    }

    public static class NullHostNameVerifier implements HostnameVerifier {
        @Override
        public boolean verify(String arg0, SSLSession arg1) {
            return true;
        }
    }

    /**
     * main函数参考如下，调用create函数创建High Level Client再调用getLowLevelClient()获取Low Level Client，并查询“test”索引是否存在。
     */
    public static void main(String[] args) throws IOException {
        RestHighLevelClient client = create(Arrays.asList("xxx.xxx.xxx.xxx", "xxx.xxx.xxx.xxx"), 9200, "http", 1000, 1000, 1000, "username", "password");
        RestClient lowLevelClient = client.getLowLevelClient();
        Request request = new Request("HEAD", "test");
        Response response = lowLevelClient.performRequest(request);
        System.out.println(response.getStatusLine().getStatusCode());
        lowLevelClient.close();
    }
}

          

        

      
     

表1 函数中的变量说明
参数	描述
host	ES集群各个节点（或者独立Client节点）的IP地址列表，当存在多个IP地址时，中间用“,”隔开。
port	ES集群的连接端口，默认是“9200”。
protocol	连接协议，“http”或者“https”，根据集群实际情况填写。
connectTimeout	socket连接超时时间。
connectionRequestTimeout	socket连接请求超时时间。
socketTimeout	socket请求超时时间。
username	访问集群的用户名。
password	用户名对应的密码。

通过Rest Low Level Client连接安全集群（使用安全证书）

方式一：直接创建Rest Low Level Client

      
       
         
         
           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.conn.ssl.NoopHostnameVerifier;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
import org.apache.http.nio.conn.ssl.SSLIOSessionStrategy;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.client.Request;
import org.elasticsearch.client.Response;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.common.Nullable;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.KeyStore;
import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;

import javax.net.ssl.SSLContext;import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

public class Main13 {

    private static final Logger logger = LogManager.getLogger(Main.class);

    /**
     * 创建客户端的类，定义create函数用于创建客户端。
     */
    public static RestClient create(List<String> host, int port, String protocol, int connectTimeout, int connectionRequestTimeout, int socketTimeout, String username, String password, String cerFilePath, String cerPassword) throws IOException {
        final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
        credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(username, password));
        SSLContext sc = null;
        try {
            TrustManager[] tm = {new MyX509TrustManager(cerFilePath, cerPassword)};
            sc = SSLContext.getInstance("SSL", "SunJSSE");
            //也可以使用SSLContext sslContext = SSLContext.getInstance("TLSv1.2");
            sc.init(null, tm, new SecureRandom());
        } catch (Exception e) {
            e.printStackTrace();
        }

        SSLIOSessionStrategy sessionStrategy = new SSLIOSessionStrategy(sc, new NoopHostnameVerifier());
        SecuredHttpClientConfigCallback httpClientConfigCallback = new SecuredHttpClientConfigCallback(sessionStrategy,
            credentialsProvider);

        RestClientBuilder builder = RestClient.builder(constructHttpHosts(host, port, protocol))
            .setRequestConfigCallback(requestConfig -> requestConfig.setConnectTimeout(connectTimeout)
                .setConnectionRequestTimeout(connectionRequestTimeout)
                .setSocketTimeout(socketTimeout))
            .setHttpClientConfigCallback(httpClientConfigCallback);
        final RestClient client = builder.build();
        logger.info("es rest client build success {} ", client);
        return client;
    }

    /**
     * constructHttpHosts函数转换host集群节点ip列表。
     */
    public static HttpHost[] constructHttpHosts(List<String> host, int port, String protocol) {
        return host.stream().map(p -> new HttpHost(p, port, protocol)).toArray(HttpHost[]::new);}

    static class SecuredHttpClientConfigCallback implements RestClientBuilder.HttpClientConfigCallback {
        @Nullable
        private final CredentialsProvider credentialsProvider;

        private final SSLIOSessionStrategy sslStrategy;

        SecuredHttpClientConfigCallback(final SSLIOSessionStrategy sslStrategy,
            @Nullable final CredentialsProvider credentialsProvider) {
            this.sslStrategy = Objects.requireNonNull(sslStrategy);
            this.credentialsProvider = credentialsProvider;
        }

        @Nullable
        CredentialsProvider getCredentialsProvider() {
            return credentialsProvider;
        }

        SSLIOSessionStrategy getSSLStrategy() {
            return sslStrategy;
        }

        @Override
        public HttpAsyncClientBuilder customizeHttpClient(final HttpAsyncClientBuilder httpClientBuilder) {
            httpClientBuilder.setSSLStrategy(sslStrategy);
            if (credentialsProvider != null) {
                httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
            }
            return httpClientBuilder;
        }}

    public static class MyX509TrustManager implements X509TrustManager {
        X509TrustManager sunJSSEX509TrustManager;

        MyX509TrustManager(String cerFilePath, String cerPassword) throws Exception {
            File file = new File(cerFilePath);
            if (!file.isFile()) {
                throw new Exception("Wrong Certification Path");
            }
            System.out.println("Loading KeyStore " + file + "...");
            InputStream in = new FileInputStream(file);
            KeyStore ks = KeyStore.getInstance("JKS");
            ks.load(in, cerPassword.toCharArray());
            TrustManagerFactory tmf = TrustManagerFactory.getInstance("SunX509", "SunJSSE");
            tmf.init(ks);
            TrustManager[] tms = tmf.getTrustManagers();
            for (TrustManager tm : tms) {
                if (tm instanceof X509TrustManager) {
                    sunJSSEX509TrustManager = (X509TrustManager) tm;
                    return;
                }
            }
            throw new Exception("Couldn't initialize");
        }

        @Override
        public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {

        }

        @Override
        public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {

        }

        @Override
        public X509Certificate[] getAcceptedIssuers() {
            return new X509Certificate[0];
        }
    }

    /**
     * main函数参考如下，调用create函数创建Rest Low Level Client，查询“test”索引是否存在。
     */
    public static void main(String[] args) throws IOException {
        RestClient lowLevelClient = create(Arrays.asList("xxx.xxx.xxx.xxx", "xxx.xxx.xxx.xxx"), 9200, "https", 1000, 1000, 1000, "username", "password", "cerFilePath", "cerPassword");
        Request request = new Request("HEAD", "test");
        Response response = lowLevelClient.performRequest(request);
        System.out.println(response.getStatusLine().getStatusCode());
        lowLevelClient.close();
    }
}

          

        

      
     

方式二：创建High Level Client再调用getLowLevelClient()获取Low Level Client

      
       
         
         
           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.conn.ssl.NoopHostnameVerifier;
import org.apache.http.impl.client.BasicCredentialsProvider;
import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
import org.apache.http.nio.conn.ssl.SSLIOSessionStrategy;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.action.admin.cluster.health.ClusterHealthRequest;
import org.elasticsearch.action.admin.cluster.health.ClusterHealthResponse;
import org.elasticsearch.client.Request;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.Response;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestClientBuilder;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.common.Nullable;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.KeyStore;
import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.Arrays;
import java.util.List;
import java.util.Objects;

import javax.net.ssl.SSLContext;import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;

public class Main {

    private static final Logger logger = LogManager.getLogger(Main.class);

    /**
     * 创建客户端的类，定义create函数用于创建客户端。
     */
    public static RestHighLevelClient create(List<String> host, int port, String protocol, int connectTimeout, int connectionRequestTimeout, int socketTimeout, String username, String password, String cerFilePath, String cerPassword) throws IOException {
        final CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
        credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(username, password));
        SSLContext sc = null;
        try {
            TrustManager[] tm = {new MyX509TrustManager(cerFilePath, cerPassword)};
            sc = SSLContext.getInstance("SSL", "SunJSSE");
            //也可以使用SSLContext sslContext = SSLContext.getInstance("TLSv1.2");
            sc.init(null, tm, new SecureRandom());
        } catch (Exception e) {
            e.printStackTrace();
        }

        SSLIOSessionStrategy sessionStrategy = new SSLIOSessionStrategy(sc, new NoopHostnameVerifier());
        SecuredHttpClientConfigCallback httpClientConfigCallback = new SecuredHttpClientConfigCallback(sessionStrategy,
            credentialsProvider);

        RestClientBuilder builder = RestClient.builder(constructHttpHosts(host, port, protocol))
            .setRequestConfigCallback(requestConfig -> requestConfig.setConnectTimeout(connectTimeout)
                .setConnectionRequestTimeout(connectionRequestTimeout)
                .setSocketTimeout(socketTimeout))
            .setHttpClientConfigCallback(httpClientConfigCallback);
        final RestHighLevelClient client = new RestHighLevelClient(builder);
        logger.info("es rest client build success {} ", client);

        ClusterHealthRequest request = new ClusterHealthRequest();
        ClusterHealthResponse response = client.cluster().health(request, RequestOptions.DEFAULT);
        logger.info("es rest client health response {} ", response);
        return client;
    }

    /**
     * constructHttpHosts函数转换host集群节点ip列表。
     */
    public static HttpHost[] constructHttpHosts(List<String> host, int port, String protocol) {
        return host.stream().map(p -> new HttpHost(p, port, protocol)).toArray(HttpHost[]::new);}

    static class SecuredHttpClientConfigCallback implements RestClientBuilder.HttpClientConfigCallback {
        @Nullable
        private final CredentialsProvider credentialsProvider;

        private final SSLIOSessionStrategy sslStrategy;

        SecuredHttpClientConfigCallback(final SSLIOSessionStrategy sslStrategy,
            @Nullable final CredentialsProvider credentialsProvider) {
            this.sslStrategy = Objects.requireNonNull(sslStrategy);
            this.credentialsProvider = credentialsProvider;
        }

        @Nullable
        CredentialsProvider getCredentialsProvider() {
            return credentialsProvider;
        }

        SSLIOSessionStrategy getSSLStrategy() {
            return sslStrategy;
        }

        @Override
        public HttpAsyncClientBuilder customizeHttpClient(final HttpAsyncClientBuilder httpClientBuilder) {
            httpClientBuilder.setSSLStrategy(sslStrategy);
            if (credentialsProvider != null) {
                httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
            }
            return httpClientBuilder;
        }}

    public static class MyX509TrustManager implements X509TrustManager {
        X509TrustManager sunJSSEX509TrustManager;

        MyX509TrustManager(String cerFilePath, String cerPassword) throws Exception {
            File file = new File(cerFilePath);
            if (!file.isFile()) {
                throw new Exception("Wrong Certification Path");
            }
            System.out.println("Loading KeyStore " + file + "...");
            InputStream in = new FileInputStream(file);
            KeyStore ks = KeyStore.getInstance("JKS");
            ks.load(in, cerPassword.toCharArray());
            TrustManagerFactory tmf = TrustManagerFactory.getInstance("SunX509", "SunJSSE");
            tmf.init(ks);
            TrustManager[] tms = tmf.getTrustManagers();
            for (TrustManager tm : tms) {
                if (tm instanceof X509TrustManager) {
                    sunJSSEX509TrustManager = (X509TrustManager) tm;
                    return;
                }
            }
            throw new Exception("Couldn't initialize");
        }

        @Override
        public void checkClientTrusted(X509Certificate[] chain, String authType) throws CertificateException {

        }

        @Override
        public void checkServerTrusted(X509Certificate[] chain, String authType) throws CertificateException {

        }

        @Override
        public X509Certificate[] getAcceptedIssuers() {
            return new X509Certificate[0];
        }
    }

    /**
     * main函数参考如下，调用create函数创建High Level Client再调用getLowLevelClient()获取Low Level Client，并查询“test”索引是否存在。
     */
    public static void main(String[] args) throws IOException {
        RestHighLevelClient client = create(Arrays.asList("xxx.xxx.xxx.xxx", "xxx.xxx.xxx.xxx"), 9200, "https", 1000, 1000, 1000, "username", "password", "cerFilePath", "cerPassword");
        RestClient lowLevelClient = client.getLowLevelClient();
        Request request = new Request("HEAD", "test");
        Response response = lowLevelClient.performRequest(request);
        System.out.println(response.getStatusLine().getStatusCode());
        lowLevelClient.close();
    }
}

          

        

      
     

表2 函数中的参数说明
参数	描述
host	ES集群各个节点（或者独立Client节点）的IP地址列表，当存在多个IP地址时，中间用“,”隔开。
port	ES集群的连接端口，默认是“9200”。
protocol	连接协议，此处填写“https”。
connectTimeout	socket连接超时时间。
connectionRequestTimeout	socket连接请求超时时间。
socketTimeout	socket请求超时时间。
username	访问集群的用户名。
password	用户名对应的密码。
cerFilePath	证书路径。
cerPassword	证书密码。

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