Elasticsearch8.x版本中RestHighLevelClient被弃用，新版本中全新的Java客户端Elasticsearch Java API Client中常用API练习

Es的java API客户端

在Es7.15版本之后，es官方将它的高级客户端RestHighLevelClient标记为弃用状态。同时推出了全新的java API客户端Elasticsearch Java API Client，该客户端也将在Elasticsearch8.0及以后版本中成为官方推荐使用的客户端。

Elasticsearch Java API Client支持除Vector title search API和Find structure API之外的所有Elasticsearch API。且支持所有API数据类型，并且不再有原始JSON Value属性。它是针对Elasticsearch8.0及之后版本的客户端。

感兴趣的小伙伴可以去官方文档看看：Elasticsearch官网8.x版本下Java客户端文档---Elasticsearch Java API Client使用

新建maven项目

maven中引入依赖坐标

        <dependency>
            <groupId>co.elastic.clients</groupId>
            <artifactId>elasticsearch-java</artifactId>
            <version>8.1.0</version>
        </dependency>
         <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.13.1</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.22</version>
            <scope>provided</scope>
        </dependency>

创建连接

    @Test
    public void create() throws IOException {
        // 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
        ElasticsearchTransport transport = new RestClientTransport(
                restClient, new JacksonJsonpMapper()
        );
        // 创建API客户端
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 关闭ES客户端
        transport.close();
        restClient.close();
    }

索引index的基本语法

创建索引

    @Test
    public void create() throws IOException {
        // 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
        ElasticsearchTransport transport = new RestClientTransport(
                restClient, new JacksonJsonpMapper()
        );
        // 创建API客户端
        ElasticsearchClient client = new ElasticsearchClient(transport);
        // 创建索引
        CreateIndexResponse createIndexResponse = client.indices().create(c -> c.index("user_test"));
        // 响应状态
        Boolean acknowledged = createIndexResponse.acknowledged();
        System.out.println("索引操作 = " + acknowledged);

        // 关闭ES客户端
        transport.close();
        restClient.close();
    }

查询索引

    @Test
    public void query() throws IOException {
        RestClient restClient = RestClient.builder(
                new HttpHost("localhost",9200)
        ).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 查询索引
        GetIndexResponse getIndexResponse = client.indices().get(e -> e.index("user_test"));
        System.out.println("getIndexResponse.result() = " + getIndexResponse.result());
        System.out.println("getIndexResponse.result().keySet() = " + getIndexResponse.result().keySet());

        transport.close();
        restClient.close();
    }

$\color{red}{注：如果查询的index不存在会在控制台抛出index_not_found_exception.}$

删除索引

    @Test
    public void delete() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 删除索引
        DeleteIndexResponse deleteIndexResponse = client.indices().delete(e -> e.index("user_test"));
        System.out.println("删除操作 = " + deleteIndexResponse.acknowledged());

        transport.close();
        restClient.close();
    }

文档document的操作

创建User对象

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private String name;
    private String sex;
    private Integer age;
}

添加document

    @Test
    public void addDocument() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 向user对象中添加数据
        User user = new User("java客户端", "男", 18);
        // 向索引中添加数据
        CreateResponse createResponse = client.create(e -> e.index("user_test").id("1001").document(user));
        System.out.println("createResponse.result() = " + createResponse.result());

        transport.close();
        restClient.close();
    }

$\color{red}{注：index中参数为文档所属的索引名，id中参数为当文档的id，document为文档数据，新版本支持直接传入java对象.} $

查询document

    @Test
    public void queryDocument() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 构建请求
        GetResponse<User> getResponse = client.get(e -> e.index("user_test").id("1001"), User.class);
        System.out.println("getResponse.source().toString() = " + getResponse.source().toString());

        transport.close();
        restClient.close();
    }

$\color{red}{注：如果查不到控制台抛出NullPointerException.}$

修改document

    @Test
    public void modifyDocument() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 使用map集合封装需要修改的内容
        Map<String, Object> map = new HashMap<>();
        map.put("name", "java客户端aaa");
        // 构建请求
        UpdateResponse<User> updateResponse = client.update(e -> e.index("user_test").id("1001").doc(map), User.class);
        System.out.println("updateResponse.result() = " + updateResponse.result());

        transport.close();
        restClient.close();
    }

删除document

    @Test
    public void removeDocument() throws  IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 构建请求
        DeleteResponse deleteResponse = client.delete(e -> e.index("user_test").id("1001"));
        System.out.println("deleteResponse.result() = " + deleteResponse.result());

        transport.close();
        restClient.close();
    }

批量添加document

    @Test
    public void batchAddDocument() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 构建一个批量数据集合
        List<BulkOperation> list = new ArrayList<>();
        list.add(new BulkOperation.Builder().create(
                d -> d.document(new User("test2", "男", 19)).id("1002").index("user_test")).build());
        list.add(new BulkOperation.Builder().create(
                d -> d.document(new User("test3", "男", 20)).id("1003").index("user_test")).build());
        list.add(new BulkOperation.Builder().create(
                d -> d.document(new User("test4", "女", 21)).id("1004").index("user_test")).build());
        // 调用bulk方法执行批量插入操作
        BulkResponse bulkResponse = client.bulk(e -> e.index("user_test").operations(list));
        System.out.println("bulkResponse.items() = " + bulkResponse.items());

        transport.close();
        restClient.close();
    }

$\color{red}{批量添加的核心是需要构建一个泛型为BulkOperation的ArrayList集合，实质上是将多个请求包装到一个集合中，进行统一请求，进行构建请求时调用bulk方法，实现批量添加效果 .}$

批量删除

    @Test
    public void batchDeleteDocument() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 构建一个批量数据集合
        List<BulkOperation> list = new ArrayList<>();
        list.add(new BulkOperation.Builder().delete(
                d -> d.id("1002").index("user_test")).build());
        list.add(new BulkOperation.Builder().delete(
                d -> d.id("1003").index("user_test")).build());
        // 调用bulk方法执行批量插入操作
        BulkResponse bulkResponse = client.bulk(e -> e.index("user_test").operations(list));
        System.out.println("bulkResponse.items() = " + bulkResponse.items());

        transport.close();
        restClient.close();
    }

全量查询

    @Test
    public void queryAllDocument() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 全量查询
        SearchResponse<User> searchResponse = client.search(e -> e.index("user_test").query(q -> q.matchAll(m -> m)), User.class);
        HitsMetadata<User> hits = searchResponse.hits();
        for (Hit<User> hit : hits.hits()) {
            System.out.println("user = " + hit.source().toString());
        }
        System.out.println("searchResponse.hits().total().value() = " + searchResponse.hits().total().value());

        transport.close();
        restClient.close();
    }

分页查询

    @Test
    public void pagingQueryDocument() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 分页查询
        SearchResponse<User> searchResponse = client.search(
                s -> s.index("user_test")
                        .query(q -> q.matchAll(m -> m))
                        .from(2)
                        .size(2)
                , User.class);
        searchResponse.hits().hits().forEach(h -> System.out.println(h.source().toString()));

        transport.close();
        restClient.close();
    }

$\color{red}{分页查询就是在全量查询的基础上增加了从第几条开始，每页显示几条 .}$

排序查询

    @Test
    public void sortQueryDocument() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 排序查询
        SearchResponse<User> searchResponse = client.search(
                s -> s.index("user_test")
                        .query(q -> q.matchAll(m -> m))
                        .sort(o -> o.field(f -> f.field("age").order(SortOrder.Asc)))
                , User.class);
        searchResponse.hits().hits().forEach(h -> System.out.println(h.source().toString()));

        transport.close();
        restClient.close();
    }

条件查询

    @Test
    public void conditionQueryDocument() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 条件查询
        SearchResponse<User> searchResponse = client.search(
                s -> s.index("user_test").query(q -> q.matchAll(m -> m))
                        .sort(o -> o.field(f -> f.field("age").order(SortOrder.Asc)))
                        .source(r -> r.filter(f -> f.includes("name", "age").excludes("")))
                , User.class);
        searchResponse.hits().hits().forEach(h -> System.out.println(h.source().toString()));

        transport.close();
        restClient.close();
    }

$\color{red}{includes是显示的字段，excludes是排除的字段.}$

组合查询

    @Test
    public void combinationQueryDocument() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 组合查询
        SearchResponse<User> searchResponse = client.search(
                s -> s.index("user_test").query(q -> q.bool(b -> b
                        .must(m -> m.match(u -> u.field("age").query(21)))
                        .must(m -> m.match(u -> u.field("sex").query("男")))
                        .mustNot(m -> m.match(u -> u.field("sex").query("女")))
                ))
                , User.class);
        searchResponse.hits().hits().forEach(h -> System.out.println(h.source().toString()));

        transport.close();
        restClient.close();
    }

    @Test
    public void combinationQueryDocument2() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 组合查询
        SearchResponse<User> searchResponse = client.search(
                s -> s.index("user_test").query(q -> q.bool(b -> b
                        .should(h -> h.match(u -> u.field("age").query(19)))
                        .should(h -> h.match(u -> u.field("sex").query("男")))
                ))
                , User.class);
        searchResponse.hits().hits().forEach(h -> System.out.println(h.source().toString()));

        transport.close();
        restClient.close();
    }

must是必须满足所有条件，should只要满足一个就行

范围查询

    @Test
    public void scopeQueryDocument2() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 范围查询，gte()表示取大于等于，gt()表示大于，lte()表示小于等于
        SearchResponse<User> searchResponse = client.search(s -> s.index("user_test").query(q -> q
                        .range(r -> r.field("age").gte(JsonData.of(20)).lt(JsonData.of(21))))
                , User.class);
        searchResponse.hits().hits().forEach(h -> System.out.println(h.source().toString()));

        transport.close();
        restClient.close();
    }

模糊查询

    @Test
    public void fuzzyQueryDocument2() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 模糊查询，fuzziness表示差几个可以查询出来
        SearchResponse<User> searchResponse = client.search(s -> s.index("user_test").query(q -> q
                        .fuzzy(f -> f.field("name").value("tst").fuzziness("2")))
                , User.class);
        searchResponse.hits().hits().forEach(h -> System.out.println(h.source().toString()));

        transport.close();
        restClient.close();
    }

高亮查询

    @Test
    public void highlightQueryDocument2() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 高亮查询
        SearchResponse<User> searchResponse = client.search(s -> s.index("user_test").query(q -> q
                        .term(t -> t.field("name").value("test3")))
                        .highlight(h -> h.fields("name", f -> f.preTags("<font color='red'>").postTags("</font>")))
                , User.class);
        searchResponse.hits().hits().forEach(h -> System.out.println(h.source().toString()));

        transport.close();
        restClient.close();
    }

聚合查询

    @Test
    public void aggregateQueryDocument2() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 聚合查询，取最大年龄
        SearchResponse<User> searchResponse = client.search(s -> s.index("user_test").aggregations("maxAge", a ->a.max(m -> m.field("age")))
                , User.class);
        searchResponse.aggregations().entrySet().forEach(f -> System.out.println(f.getKey() + ":" + f.getValue().max().value()));

        transport.close();
        restClient.close();
    }

分组查询

    @Test
    public void groupQueryDocument2() throws IOException {
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200)).build();
        ElasticsearchTransport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // 分组查询
        SearchResponse<User> searchResponse = client.search(s -> s.index("user_test")
                        .aggregations("ageGroup", a ->a.terms(t -> t.field("age")))
                , User.class);
        searchResponse.aggregations().get("ageGroup").lterms().buckets().array().forEach(f -> System.out.println(f.key() + ":" + f.docCount()));

        transport.close();
        restClient.close();
    }

$\color{red}{分组查询实质上是聚合查询的一种.}$

最后编辑于：2022.04.13 09:19:30

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