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(); }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(); }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(); }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(); }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(); }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(); }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(); }分组查询实质上是聚合查询的一种
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