ElasticSearch-02-JavaApi

简述

通过在 Java 编程中控制 ElasticSearch。

  • 截至笔记实践，已更新到了8.8.0版本。
  • ES 的 7.15.x 版本以上及以下 的 Api 使用有区别

ES 7.15.x 以下使用

ES 7.15.x 以上使用

  • 引入依赖

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    <dependencies>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.15.2</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.15.2</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.15.2</version>
        </dependency>
        <dependency>
            <groupId>co.elastic.clients</groupId>
            <artifactId>elasticsearch-java</artifactId>
            <version>7.17.10</version>
        </dependency>
        <dependency>
            <groupId>jakarta.json</groupId>
            <artifactId>jakarta.json-api</artifactId>
            <version>2.0.1</version>
        </dependency>
        <dependency>
            <groupId>org.elasticsearch.client</groupId>
            <artifactId>elasticsearch-rest-client</artifactId>
            <version>7.17.10</version>
        </dependency>
        <dependency>
            <groupId>commons-logging</groupId>
            <artifactId>commons-logging</artifactId>
            <version>1.2</version>
        </dependency>
    </dependencies>

  • 获得客户端 （可以封装成一个工具类）

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    /**
     * @author 75654
     * @date 2023/6/4 15:37
     *
     * ElasticSearch JavaApi学习
     */
    public class App {
        public static void main(String[] args) throws IOException {
            // 创建 JavaApi 客户端
            // new RestHighLevelClient 7.15.x 后已被启用
            // 创建低级客户端
            RestClient restClient = RestClient.builder(
                    new HttpHost("localhost", 9200)).build();
            // 使用Jackson映射器创建传输层
            // 也可以使用 ElasticsearchTransport 接收 restClientTransport
            // ElasticsearchTransport 是 RestClientTransport 的接口
            RestClientTransport restClientTransport = new RestClientTransport(restClient, new JacksonJsonpMapper());
            // 创建API客户端
            ElasticsearchClient client = new ElasticsearchClient(restClientTransport);

            // 查询：索引 wang 下的配置信息
            GetIndexResponse indexResponse = client.indices().get(s -> s.index("wang"));
            indexResponse.result().forEach( (k, v) -> System.out.println("k=" + k + ", v=" + v));

            restClientTransport.close();
        }
    }

    结果信息：

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    六月 04, 2023 5:57:50 下午 org.elasticsearch.client.RestClient logResponse
    警告: request [GET http://localhost:9200/wang] returned 1 warnings: [299 Elasticsearch-7.17.10-fecd68e3150eda0c307ab9a9d7557f5d5fd71349 "Elasticsearch built-in security features are not enabled. Without authentication, your cluster could be accessible to anyone. See https://www.elastic.co/guide/en/elasticsearch/reference/7.17/security-minimal-setup.html to enable security."]
    k=wang, v=IndexState: {"aliases":{},"mappings":{},"settings":{"index":{"number_of_shards":"1","number_of_replicas":"1","routing":{"allocation":{"include":{"_tier_preference":"data_content"}}},"provided_name":"wang","creation_date":"1685872659618","uuid":"whZRN2vdTWKJPvMUMymmrg","version":{"created":"7171099"}}}}

    Process finished with exit code 0

获取 Elasticsearch Client 对象

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// 创建 JavaApi 客户端
// new RestHighLevelClient 7.15.x 后已被启用
// 创建低级客户端
RestClient restClient = RestClient.builder(
    new HttpHost("localhost", 9200)).build();
// 使用Jackson映射器创建传输层
// 也可以使用 ElasticsearchTransport 接收 restClientTransport
// ElasticsearchTransport 是 RestClientTransport 的接口
RestClientTransport restClientTransport = new RestClientTransport(restClient, new JacksonJsonpMapper());
// 创建API客户端
ElasticsearchClient esClient = new ElasticsearchClient(restClientTransport);

索引操作

  1. 创建索引

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    private static void createIndex() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchClient esClient = new ElasticsearchClient(
            new RestClientTransport(restClient, new JacksonJsonpMapper()));
        // 创建 user 索引
        CreateIndexResponse createIndexResponse = esClient.indices().create(s -> s.index("user"));
        boolean acknowledged = createIndexResponse.acknowledged();
        boolean b = createIndexResponse.shardsAcknowledged();
        String index = createIndexResponse.index();
        System.out.println(acknowledged);
        System.out.println(b);
        System.out.println(index);

        restClient.close();
    }

  2. 查看索引

    • 指定索引

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      private static void searchIndex() throws IOException {
          RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
          ElasticsearchClient esClient = new ElasticsearchClient(
              new RestClientTransport(restClient, new JacksonJsonpMapper()));
          // 查询 user 索引
          GetIndexResponse getIndexResponse = esClient.indices().get(s -> s.index("user"));
          Map<String, IndexState> result = getIndexResponse.result();
          Set<Map.Entry<String, IndexState>> entries = result.entrySet();
          for (Map.Entry<String, IndexState> entry : entries) {
              System.out.println("Key==" + entry.getKey());
              System.out.println("Value==" + entry.getValue());
          }
      }

    • 全部索引

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      private static void searchIndexAll() throws IOException {
          RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
          ElasticsearchClient esClient = new ElasticsearchClient(
              new RestClientTransport(restClient, new JacksonJsonpMapper()));
          // 查询全部索引 cat
          IndicesResponse indicesResponse = esClient.cat().indices();

          List<IndicesRecord> indicesRecords = indicesResponse.valueBody();
          for (IndicesRecord indicesRecord : indicesRecords) {
              System.out.println("index==" + indicesRecord);
          }
      }

  3. 删除索引

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    private static void deleteIndex() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchClient esClient = new ElasticsearchClient(
            new RestClientTransport(restClient, new JacksonJsonpMapper()));
        // 删除索引 user
        DeleteIndexResponse deleteIndexResponse = esClient.indices().delete(s -> s.index("user"));

        boolean acknowledged = deleteIndexResponse.acknowledged();
        System.out.println(acknowledged);

        restClient.close();
    }

文档操作

  1. 创建文档
  • 单个创建
  • 批量创建 - BulkOperation
    2.
    查看文档
  • 查看指定文档
  • 查看索引下所有文档
  1. 修改文档
  • 覆盖式修改
  • 部分修改 - map
  1. 删除文档
  • 指定删除
    • 批量删除 - BulkOperation

**代码： **DocTest.md

★复杂文档查询

  • 复杂查询:
    • 1.条件查询 2.分页、排序 3.过滤字段 4.模糊查询 5.高亮查询
  • 聚合查询:
    • 1.最大值 2.分组统计

**代码： **QueryTest.md

问题

  1. Exception in thread “main” java.lang.NoClassDefFoundError: org/elasticsearch/client/Cancellable

    原因： elasticsearch-rest-high-level-client内部引用的是低版本，版本不一致

    image-20230531174214742

    解决：引入高版本，覆盖旧版本

  2. ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console. Set system property ‘org.apache.logging.log4j.simplelog.StatusLogger.level’ to TRACE to show Log4j2 internal initialization logging.

    原因：没有 log4j2 的配置文件

    解决：添加 log4j2 的配置文件

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    <?xml version="1.0" encoding="UTF-8"?>
    <Configuration status="WARN">
        <Appenders>
            <Console name="Console" target="SYSTEM_OUT">
                <PatternLayout pattern="[%-5p] %d %c - %m%n" />
            </Console>
            <File name="File" fileName="D:/log/elasticsearch.log">
                <PatternLayout pattern="%m%n" />
            </File>
        </Appenders>

        <Loggers>
            <Logger name="mh.sample2.Log4jTest2" level="INFO">
                <AppenderRef ref="File" />
            </Logger>
            <Root level="INFO">
                <AppenderRef ref="Console" />
            </Root>
        </Loggers>
    </Configuration>

  3. Exception in thread “main” java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory

    原因：缺少 commons-logging 包

    解决：引入 commons-logging 包依赖

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    <!-- https://mvnrepository.com/artifact/commons-logging/commons-logging -->
    <dependency>
        <groupId>commons-logging</groupId>
        <artifactId>commons-logging</artifactId>
        <version>1.2</version>
    </dependency>

  4. com/fasterxml/jackson/core/util/JacksonFeature

    原因：jackson-databind、jackson-core、jackson-annotations 版本不一致。（databind 中 包含 core、annotations 但是版本不一致）

    解决：将 jackson-databind、jackson-core、jackson-annotations 版本覆盖。

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    <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.15.2</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.15.2</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>2.15.2</version>
    </dependency>

  5. jakarta/json/JsonException

    原因：Json 版本较低

    解决：指定版本覆盖

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    <!-- https://mvnrepository.com/artifact/jakarta.json/jakarta.json-api -->
    <dependency>
        <groupId>jakarta.json</groupId>
        <artifactId>jakarta.json-api</artifactId>
        <version>2.0.1</version>
    </dependency>