Elastic Search 的底层是开源库 Lucene。但是Lucene的使用门槛比较高，必须自己写代码去调用它的接口。而Elastic Search的出现正是为了解决了这个问题，它是 Lucene 的封装，提供了 REST API 的操作接口，我们可以开箱即用。

环境

• JDK版本：8
• SpringBoot:2.x
• ES版本：7.1.1

依赖

        <!--   集成es client，并排除低版本依赖(5.6)     -->
        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-high-level-client</artifactId>
            <version>7.1.1</version>
            <exclusions>
                <exclusion>
                    <groupId>org.elasticsearch</groupId>
                    <artifactId>elasticsearch</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.elasticsearch.client</groupId>
                    <artifactId>elasticsearch-rest-client</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-client</artifactId>
            <version>7.1.1</version>
        </dependency>
        <dependency>
            <groupId>org.elasticsearch</groupId>
            <artifactId>elasticsearch</artifactId>
            <version>7.1.1</version>
        </dependency>

配置

使用配置类配置，可以参考如下所示：
先创建一个builder，用于初始化ES client

public class EsClientBuilder {
    private int connectTimeoutMillis = 1000;
    private int socketTimeoutMillis = 30000;
    private int connectionRequestTimeoutMillis = 500;
    private int maxConnectPerRoute = 10;
    private int maxConnectTotal = 30;

    private final List<HttpHost> httpHosts;


    private EsClientBuilder(List<HttpHost> httpHosts) {
        this.httpHosts = httpHosts;
    }


    public EsClientBuilder setConnectTimeoutMillis(int connectTimeoutMillis) {
        this.connectTimeoutMillis = connectTimeoutMillis;
        return this;
    }

    public EsClientBuilder setSocketTimeoutMillis(int socketTimeoutMillis) {
        this.socketTimeoutMillis = socketTimeoutMillis;
        return this;
    }

    public EsClientBuilder setConnectionRequestTimeoutMillis(int connectionRequestTimeoutMillis) {
        this.connectionRequestTimeoutMillis = connectionRequestTimeoutMillis;
        return this;
    }

    public EsClientBuilder setMaxConnectPerRoute(int maxConnectPerRoute) {
        this.maxConnectPerRoute = maxConnectPerRoute;
        return this;
    }

    public EsClientBuilder setMaxConnectTotal(int maxConnectTotal) {
        this.maxConnectTotal = maxConnectTotal;
        return this;
    }


    public static EsClientBuilder build(List<HttpHost> httpHosts) {
        return new EsClientBuilder(httpHosts);
    }


    public RestHighLevelClient create() {

        HttpHost[] httpHostArr = httpHosts.toArray(new HttpHost[0]);
        RestClientBuilder builder = RestClient.builder(httpHostArr);

        builder.setRequestConfigCallback(requestConfigBuilder -> {
            requestConfigBuilder.setConnectTimeout(connectTimeoutMillis);
            requestConfigBuilder.setSocketTimeout(socketTimeoutMillis);
            requestConfigBuilder.setConnectionRequestTimeout(connectionRequestTimeoutMillis);
            return requestConfigBuilder;
        });

        builder.setHttpClientConfigCallback(httpClientBuilder -> {
            httpClientBuilder.setMaxConnTotal(maxConnectTotal);
            httpClientBuilder.setMaxConnPerRoute(maxConnectPerRoute);
            return httpClientBuilder;
        });

        return new RestHighLevelClient(builder);
    }
}

再交给spring容器管理：

@Configuration
public class ESConfig {
    @Value("${elasticsearch.nodes}")
    private List<String> nodes;

    @Value("${elasticsearch.schema}")
    private String schema;

    @Value("${elasticsearch.max-connect-total}")
    private Integer maxConnectTotal;

    @Value("${elasticsearch.max-connect-per-route}")
    private Integer maxConnectPerRoute;

    @Value("${elasticsearch.connection-request-timeout-millis}")
    private Integer connectionRequestTimeoutMillis;

    @Value("${elasticsearch.socket-timeout-millis}")
    private Integer socketTimeoutMillis;

    @Value("${elasticsearch.connect-timeout-millis}")
    private Integer connectTimeoutMillis;

    @Bean
    public RestHighLevelClient getRestHighLevelClient() {
        List<HttpHost> httpHosts = new ArrayList<>();
        for (String node : nodes) {
            try {
                String[] parts = StringUtils.split(node, ":");
                Assert.notNull(parts,"Must defined");
                Assert.state(parts.length == 2, "Must be defined as 'host:port'");
                httpHosts.add(new HttpHost(parts[0], Integer.parseInt(parts[1]), schema));
            } catch (RuntimeException ex) {
                throw new IllegalStateException(
                        "Invalid ES nodes " + "property '" + node + "'", ex);
            }
        }

        return EsClientBuilder.build(httpHosts)
                .setConnectionRequestTimeoutMillis(connectionRequestTimeoutMillis)
                .setConnectTimeoutMillis(connectTimeoutMillis)
                .setSocketTimeoutMillis(socketTimeoutMillis)
                .setMaxConnectTotal(maxConnectTotal)
                .setMaxConnectPerRoute(maxConnectPerRoute)
                .create();
    }
}

再配置一下常用的配置：

#配置es
elasticsearch:
  #  如果是cluster，application.yml的nodes设置多个ip:host逗号隔开即可。
  nodes: 127.0.0.1:9200
  schema: http
  max-connect-total: 50
  max-connect-per-route: 10
  connection-request-timeout-millis: 500
  socket-timeout-millis: 30000
  connect-timeout-millis: 1000

使用

接下来我们测试一下配置是否生效，一个简单的验证送给大家，如下所示：

@Autowired
    private RestHighLevelClient client;
    @Test
    public void test() throws IOException {
        MainResponse info = client.info(RequestOptions.DEFAULT);
        System.out.println(info.toString());
    }

配置生效的话，就会返回Elastic Search的配置信息：包含当前节点、集群、版本等信息。
SpringBoot集成ES至此结束。

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