前言
Elasticsearch官方列出了好几个客户端，如下所示
- Java Client
- Java Rest Client（Java High Level REST Client）
- Java Transport Client
其中Java Rest Client在7.15.0被标记已过时，Java Transport Client暂时没找到在哪个版本被标记过时
注：
- 官方文档
- Spring Boot 2.3.12.RELEASE
- Elasticsearch 7.17.5
Java Client 集成
Java Client在构建对象时支持Build模式以及Lambda两种形式，暴露出来的API为ElasticsearchClient类，通过该类可进行对索引、文档的基本操作。
ElasticsearchClient对象初始化步骤
第一步，引入依赖
<dependency>
<groupId>co.elastic.clients</groupId>
<artifactId>elasticsearch-java</artifactId>
<version>7.17.5</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.12.3</version>
</dependency>
<dependency>
<groupId>jakarta.json</groupId>
<artifactId>jakarta.json-api</artifactId>
<version>2.0.1</version>
</dependency>
在Spring Boot项目中，如果引入了以下依赖，便不用单独引入jackson-databind依赖了
<!-- 已经包含了jackson-databind -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
第二步，配置ObjectMapper
如果不想自定义ObjectMapper的行为，可以省略，这里主要想要支持LocalDate、LocalDateTime类，不然文档中如果包含时间列，反序列成对象时会报错。
在Spring Boot项目中只需加入以下配置即可
package com.wangtao.msgsearch.config;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;
import org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
import org.springframework.stereotype.Component;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
@Component
public class JacksonCustomizer implements Jackson2ObjectMapperBuilderCustomizer {
private static final String STANDARD_PATTERN = "yyyy-MM-dd HH:mm:ss";
private static final String DATE_PATTERN = "yyyy-MM-dd";
private static final String TIME_PATTERN = "HH:mm:ss";
@Override
public void customize(Jackson2ObjectMapperBuilder builder) {
// 初始化JavaTimeModule
JavaTimeModule javaTimeModule = new JavaTimeModule();
//处理LocalDateTime
DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern(STANDARD_PATTERN);
javaTimeModule.addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(dateTimeFormatter));
javaTimeModule.addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(dateTimeFormatter));
//处理LocalDate
DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern(DATE_PATTERN);
javaTimeModule.addSerializer(LocalDate.class, new LocalDateSerializer(dateFormatter));
javaTimeModule.addDeserializer(LocalDate.class, new LocalDateDeserializer(dateFormatter));
//处理LocalTime
DateTimeFormatter timeFormatter = DateTimeFormatter.ofPattern(TIME_PATTERN);
javaTimeModule.addSerializer(LocalTime.class, new LocalTimeSerializer(timeFormatter));
javaTimeModule.addDeserializer(LocalTime.class, new LocalTimeDeserializer(timeFormatter));
/*
* 1. java.util.Date yyyy-MM-dd HH:mm:ss
* 2. 支持JDK8 LocalDateTime、LocalDate、 LocalTime
* 3. Jdk8Module模块支持如Stream、Optional等类
* 4. 序列化时包含所有字段
* 5. 在序列化一个空对象时时不抛出异常
* 6. 忽略反序列化时在json字符串中存在, 但在java对象中不存在的属性
* 7. 数字序列化成字符穿且调用BigDecimal.toPlainString()方法
*/
builder.simpleDateFormat(STANDARD_PATTERN)
.modules(javaTimeModule, new Jdk8Module())
.serializationInclusion(JsonInclude.Include.ALWAYS)
.failOnEmptyBeans(false)
.failOnUnknownProperties(false)
.featuresToEnable(JsonGenerator.Feature.WRITE_BIGDECIMAL_AS_PLAIN);
}
}
第三步，将ElasticsearchClient对象注册到Spring容器中
package com.wangtao.msgsearch.config;
import co.elastic.clients.elasticsearch.ElasticsearchClient;
import co.elastic.clients.json.jackson.JacksonJsonpMapper;
import co.elastic.clients.transport.ElasticsearchTransport;
import co.elastic.clients.transport.rest_client.RestClientTransport;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.http.HttpHost;
import org.elasticsearch.client.RestClient;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class ElasticsearchConfig {
@Bean
public ElasticsearchClient elasticsearchClient(ObjectMapper objectMapper) {
RestClient restClient = RestClient.builder(
new HttpHost("localhost", 9200)).build();
ElasticsearchTransport transport = new RestClientTransport(
restClient, new JacksonJsonpMapper(objectMapper));
return new ElasticsearchClient(transport);
}
}
API使用
现在就可以来感受下Elasticsearch Java Client API链式以及lambda风格
先准备测试数据
建立索引
PUT /user
{
"mappings": {
"properties": {
"userId": {
"type": "integer",
"index": true
},
"name": {
"type": "text",
"index": true
},
"age": {
"type": "integer",
"index": true
},
"birthday": {
"type": "date",
"index": true
},
"createTime": {
"type": "date",
"index": false,
"format": "yyyy-MM-dd HH:mm:ss"
}
}
}
}
插入数据
POST /user/_bulk
{"index": {"_id": 1}}
{"userId": 1, "name" : "zhang san", "age" : 20, "birthday" : "2021-08-20", "createTime" : "2022-08-20 12:10:30"}
{"index": {"_id": 2}}
{"userId": 2, "name" : "li si", "age" : 20, "birthday" : "2022-08-20", "createTime" : "2022-08-20 12:10:30"}
{"index": {"_id": 3}}
{"userId": 3, "name" : "zhang san shuo", "age" : 25, "birthday" : "2022-08-20", "createTime" : "2022-08-20 12:10:30"}
{"index": {"_id": 4}}
{"userId": 4, "name" : "wang wu", "age" : 20, "birthday" : "2021-08-20", "createTime" : "2022-08-20 12:10:30"}
根据文档ID查询数据
lambda表达式
@GetMapping("/{docId}")
public User getByDocId(@PathVariable String docId) throws IOException {
GetResponse<User> reponse = elasticsearchClient.get(
g -> g.index("user").id(docId),
User.class
);
if (reponse.found()) {
return reponse.source();
} else {
throw new IllegalArgumentException("not found " + docId);
}
}
Build模式
@GetMapping("/getByDocIdFluent/{docId}")
public User getByDocIdFluent(@PathVariable String docId) throws IOException {
GetRequest getRequest = new GetRequest.Builder()
.index("user")
.id(docId)
.build();
GetResponse<User> reponse = elasticsearchClient.get(getRequest, User.class);
if (reponse.found()) {
return reponse.source();
} else {
throw new IllegalArgumentException("not found " + docId);
}
}
搜索操作
实现效果: where name like '%zhang%' and age in (25, 20)
@GetMapping("/search")
public List<User> search() throws IOException {
Query byName = new MatchQuery.Builder()
.field("name")
.query("zhang")
.build()._toQuery();
TermsQueryField termsQueryField = new TermsQueryField.Builder()
.value(Arrays.asList(FieldValue.of(25), FieldValue.of(20)))
.build();
Query inAge = new TermsQuery.Builder()
.field("age")
.terms(termsQueryField)
.build()._toQuery();
Query query = new BoolQuery.Builder()
.must(byName, inAge)
.build()._toQuery();
SearchRequest searchRequest = new SearchRequest.Builder()
.index("user")
.query(query)
.build();
SearchResponse<User> response = elasticsearchClient.search(
searchRequest, User.class);
List<Hit<User>> hits = response.hits().hits();
return hits.stream().map(Hit::source).collect(Collectors.toList());
}