【ElasticSearch】Java整合ES

Java整合ES

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1 环境准备

1.1 依赖

• 演示的ES版本为8.x版本，8.x版本抛弃了rest-high-level-client的依赖的使用，改用新的依赖，若ES版本为8.x之前的，查看rest-high-level-client对应的使用

<!-- es-java整合 -->
<dependency>
	<groupId>co.elastic.clients</groupId>
	<artifactId>elasticsearch-java</artifactId>
	<version>8.1.2</version>
</dependency>
<!-- jackson-json处理 -->
<dependency>
	<groupId>com.fasterxml.jackson.core</groupId>
	<artifactId>jackson-databind</artifactId>
	<version>2.13.2.2</version>
</dependency>

1.2 连接ES

• 因为连接ES比较常用，直接封装为工具类

public class ESUtil {
    // 获取ES客户端
    public static ElasticsearchClient getEsClient() {
        RestClient restClient = RestClient.builder(
                // 地址, 端口, 通信协议（http/https）
                new HttpHost("localhost", 9200, "http")
        ).build();
        RestClientTransport restClientTransport = new RestClientTransport(restClient, new JacksonJsonpMapper());
        return new ElasticsearchClient(restClientTransport);
    }
}

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2 索引使用

2.1 创建索引

// 创建索引
@Test
public void createIndex() throws Exception{
    ElasticsearchClient esClient = ESUtil.getEsClient();
    CreateIndexResponse createIndexResponse = esClient.indices().create(c -> c.index("user"));
    System.out.println(createIndexResponse);
}

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2.2 查询索引

// 查询索引
@Test
public void getIndex() throws Exception{
    ElasticsearchClient esClient = ESUtil.getEsClient();
    GetIndexResponse getIndexResponse = esClient.indices().get(i -> i.index("user"));
    // 获取响应数据
    IndexState indexState = getIndexResponse.result().get("user");
    System.out.println(indexState);
}

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2.3 删除索引

// 删除索引
@Test
public void deleteIndex() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    DeleteIndexResponse deleteIndexResponse = esClient.indices().delete(i -> i.index("user"));
    System.out.println(deleteIndexResponse);
}

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3 文档使用

• 创建一个User类，当作文档存储的数据

// 需要引入lombok依赖
@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {
    private Integer id;
    private String name;
    private Integer age;
    private String sex;
}

3.1 创建文档

// 创建文档
@Test
public void createDocument() throws Exception{
    ElasticsearchClient esClient = ESUtil.getEsClient();
    User user = new User(1001, "letere", 18, "男");
    CreateResponse createResponse = esClient.create(i -> i.index("user").id("1002").document(user));
    System.out.println(createResponse);
}

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3.2 更新文档

// 更新文档
@Test
public void updateDocument() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    User user = new User(1001, "letere", 18, "女");
    UpdateResponse<User> updateResponse = esClient.update(i -> i.index("user").id("1001").doc(user), User.class);
    System.out.println(updateResponse);
}

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3.3 查询文档

// 查询文档
@Test
public void getDocument() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    GetResponse<User> getResponse = esClient.get(i -> i.index("user").id("1001"), User.class);
    System.out.println(getResponse.source());
}

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3.4 删除文档

// 删除文档
@Test
public void deleteDocument() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    DeleteResponse deleteResponse = esClient.delete(i -> i.index("user").id("1001"));
    System.out.println(deleteResponse);
}

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4 文档批量处理

4.1 批量创建

// 批量创建文档
@Test
public void batchCreateDocument() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    List<User> users = new ArrayList<>();
    users.add(new User(1001, "letere", 18, "男"));
    users.add(new User(1002, "glucat", 22, "男"));
    users.add(new User(1003, "咕料", 30, "男"));
    users.add(new User(1004, "C酱", 28, "女"));
    // 转成List<BulkOperation>
    List<BulkOperation> bulkOperations = new ArrayList<>();
    for (User user : users) {
        bulkOperations.add(BulkOperation.of(
                b -> b.create(
                        d -> d.id(user.getId().toString()).document(user)
                )
        ));
    }
    BulkResponse response = esClient.bulk(i -> i.index("user").operations(bulkOperations));
    System.out.println(response.items());
}

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4.2 批量删除

// 批量删除文档
@Test
public void batchDeleteDocument() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    String[] ids = new String[]{"1001", "1002"};
    // 转成List<BulkOperation>
    List<BulkOperation> bulkOperations = new ArrayList<>();
    for (String id : ids) {
        bulkOperations.add(BulkOperation.of(
                b -> b.delete(
                        d -> d.id(id)
                )
        ));
    }
    BulkResponse response = esClient.bulk(i -> i.index("user").operations(bulkOperations));
    System.out.println(response.items());
}

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5 文档进阶查询

5.1 全量查询

// 全量查询
@Test
public void queryAll() throws Exception{
    ElasticsearchClient esClient = ESUtil.getEsClient();
    SearchResponse<User> searchResponse = esClient.search(
            s -> s.index("user")
                    .query(q -> q
                            .matchAll(m -> m)),
            User.class
    );
    for (Hit<User> userHit : searchResponse.hits().hits()) {
        System.out.println(userHit.source());
    }
}

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5.2 条件查询

// 条件查询
@Test
public void wrapperQuery() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    SearchResponse<User> searchResponse = esClient.search(
            s -> s.index("user")
                    .query(q -> q
                            // term为完全匹配查询, match为分词匹配
                            // 查询的字段有中文时，field里填写'字段名.keyword'，例age.keyword
                            .term(t -> t
                                    .field("age")
                                    .value(30))),
            User.class
    );
    for (Hit<User> userHit : searchResponse.hits().hits()) {
        System.out.println(userHit.source());
    }
}

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5.3 组合条件查询

// 组合条件查询
@Test
public void boolQuery() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    SearchResponse<User> searchResponse = esClient.search(
            s -> s.index("user")
                    .query(q -> q
                            .bool(b -> b
                                    // must类似sql的and，should类似sql的or
                                    .must(m -> m
                                            .term(t -> t
                                                    .field("sex.keyword")
                                                    .value("男"))
                                    )
                                    .must(m -> m
                                            .match(ma -> ma
                                                    .field("name")
                                                    .query("letere"))
                                    ))),
            User.class
    );
    for (Hit<User> userHit : searchResponse.hits().hits()) {
        System.out.println(userHit.source());
    }
}

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5.4 范围查询

// 范围查询
@Test
public void rangeQuery() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    SearchResponse<User> searchResponse = esClient.search(
            s -> s.index("user")
                    .query(q -> q
                            .range(r -> r
                                    .field("age")
                                    .gt(JsonData.of(20))
                                    .lt(JsonData.of(30)))),
            User.class
    );
    for (Hit<User> userHit : searchResponse.hits().hits()) {
        System.out.println(userHit.source());
    }
}

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5.5 模糊查询

// 模糊查询
@Test
public void fuzzyQuery() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    SearchResponse<User> searchResponse = esClient.search(
            s -> s.index("user")
                    .query(q -> q
                            .fuzzy(f -> f
                                    .field("name")
                                    .value("lete")
                                    .fuzziness("2"))), // 偏差字符长度，偏差长度<=2的，可以查询出来
            User.class
    );
    for (Hit<User> userHit : searchResponse.hits().hits()) {
        System.out.println(userHit.source());
    }
}

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5.6 分页查询

// 分页查询
@Test
public void pageQuery() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    SearchResponse<User> searchResponse = esClient.search(
            s -> s.index("user")
                    .query(q -> q
                            .matchAll(m -> m))
                    .from(0)
                    .size(2),
            User.class
    );
    for (Hit<User> userHit : searchResponse.hits().hits()) {
        System.out.println(userHit.source());
    }
}

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5.7 排序查询

// 排序查询
@Test
public void sortQuery() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    SearchResponse<User> searchResponse = esClient.search(
            s -> s.index("user")
                    .query(q -> q
                            .matchAll(m -> m))
                    .sort(so -> so
                            .field(f -> f
                                    .field("age")
                                    .order(SortOrder.Desc))),
            User.class
    );
    for (Hit<User> userHit : searchResponse.hits().hits()) {
        System.out.println(userHit.source());
    }
}

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5.8 指定字段查询

// 指定字段查询
@Test
public void fieldQuery() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    SearchResponse<User> searchResponse = esClient.search(
            s -> s.index("user")
                    .query(q -> q
                            .matchAll(m -> m))
                    .source(so -> so
                            .filter(f -> f
                                    .includes("name", "age", "sex")
                                    .excludes(""))),
            User.class
    );
    for (Hit<User> userHit : searchResponse.hits().hits()) {
        System.out.println(userHit.source());
    }
}

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5.9 高亮查询

// 高亮查询
@Test
public void highLightQuery() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    SearchResponse<User> searchResponse = esClient.search(
            s -> s.index("user")
                    .query(q -> q
                            .term(t -> t
                                    .field("name.keyword")
                                    .value("咕料")))
                    .highlight(h -> h
                            .fields("name.keyword", f -> f
                                    .preTags("<font color='red'>")
                                    .postTags("</font>"))),
            User.class
    );
    for (Hit<User> userHit : searchResponse.hits().hits()) {
        System.out.println(userHit.highlight());
    }
}

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5.10 聚合查询

// 聚合查询
@Test
public void groupQuery() throws Exception {
    ElasticsearchClient esClient = ESUtil.getEsClient();
    SearchResponse<User> searchResponse = esClient.search(
            s -> s.index("user")
                    .aggregations("sexCount", a -> a.terms(t -> t.field("sex.keyword"))),
            User.class
    );
    // 根据查询的字段数据类型选择对应的terms，string选择sterms，数字选择lterms
    for (StringTermsBucket stringTermsBucket : searchResponse.aggregations().get("sexCount").sterms().buckets().array()) {
        System.out.println(stringTermsBucket.key() + ":" + stringTermsBucket.docCount());
    }
}

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