Elasticsearch运用于实际的SpringBoot项目

一、SpringBoot整合Elasticsearch

1.spring boot 引入对应的依赖包

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-elasticsearch</artifactId>
<version>2.2.2.RELEASE</version>
</dependency>

注意：这里的依赖包版本必须与es服务版本对应，比如，上述依赖包2.2.2.RELEASE就对应着elasticsearch-6.4.3。

2.在yml文件中配置相应的es服务信息

spring:
data:
elasticsearch:
cluster-name: es6
cluster-nodes: 192.168.1.9:9300

3.常见错误解决
（1）如果出现如下错误

java.lang.IllegalStateException: availableProcessors is already set to [4], rejecting [4]

解决：

@Configuration
public class ESConfig {

/**
* 解决由netty引起的问题
*/
@PostConstruct
void init() {
System.setProperty("es.set.netty.runtime.available.processors", "false");
}
}

二、Elasticsearch在SpringBoot中的应用

不建议通过ElasticsearchTemplate 在spring boot中对索引进行直接管理。有两个原因：第一，因为索引就相当于数据库表，在Java中我们是不会通过代码频繁的去建表、删表的。同理es也是一样；第二，通过Java建索引不够灵活，很多类型(FieldType)不能通过Java设置，并且主分片与副本分片不能通过Java来设置。
1.关于索引的操作
（1）索引的创建与更新

第一步：创建文档类

package imooc.es.pojo;

import lombok.Getter;
import lombok.Setter;
import org.springframework.data.annotation.Id;
import org.springframework.data.elasticsearch.annotations.Document;
import org.springframework.data.elasticsearch.annotations.Field;

@Document(indexName = "stu",type = "_doc")
@Data
public class Stu {

@Id
private Long stuId;

@Field(store = true)
private String name;

@Field(store = true)
private Integer age;

@Field(store = true)
private Float money;

@Field(store = true)
private String sign;

@Field(store = true)
private String description;
}

第二步：创建索引或更新索引
如果该文档记录在索引中存在，即更新，不存在则新增

package com.test;

import imooc.Application;
import imooc.es.pojo.Stu;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.elasticsearch.core.ElasticsearchTemplate;
import org.springframework.data.elasticsearch.core.query.IndexQuery;
import org.springframework.data.elasticsearch.core.query.IndexQueryBuilder;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest(classes = Application.class)
public class ESTest {

@Autowired
private ElasticsearchTemplate esTemplate;

@Test
public void createIndexStu() {

Stu stu = new Stu();
stu.setStuId(1002L);
stu.setName("spider man");
stu.setAge(19);
IndexQuery indexQuery = new IndexQueryBuilder().withObject(stu).build();
esTemplate.index(indexQuery);
}
}

（2）索引的删除

@Test
public void deleteIndexStu() {

esTemplate.deleteIndex(Stu.class);
}

2.关于文档的操作
（1）文档更新

@Test
public void updateStuDoc() {

Map<String, Object> source = new HashMap<>();
source.put("money",66.8F);
source.put("sign","i am nononono");

IndexRequest indexRequest = new IndexRequest();
indexRequest.source(source);

UpdateQuery updateQuery = new UpdateQueryBuilder()
.withClass(Stu.class)
.withId("1002")
.withIndexRequest(indexRequest)
.build();
esTemplate.update(updateQuery);
}

（2）文档查询

@Test
public void queryStuDoc() {

GetQuery getQuery = new GetQuery();
getQuery.setId("1002");
Stu stu = esTemplate.queryForObject(getQuery, Stu.class);
System.out.println(stu);
}

（3）文档删除

@Test
public void deleteStuDoc() {

String delete = esTemplate.delete(Stu.class, "1002");
System.out.println(delete);
}

（4）文档分页搜索

@Test
public void searchStuDocForPage() {

Pageable pageable = PageRequest.of(0, 10);
NativeSearchQuery searchQuery = new NativeSearchQueryBuilder()
.withQuery(QueryBuilders.matchQuery("description", "super man"))
.withPageable(pageable)
.build();
AggregatedPage<Stu> stus = esTemplate.queryForPage(searchQuery, Stu.class);
System.out.println(stus.getTotalPages());
System.out.println(stus.getContent());
}

（5）搜索内容高亮显示

@Test
public void searchStuDocForHighLight() {

String preTags = "<font color='red'>";
String postTags = "</font>";
Pageable pageable = PageRequest.of(0, 2);
NativeSearchQuery searchQuery = new NativeSearchQueryBuilder()
.withQuery(QueryBuilders.matchQuery("description", "man"))
.withHighlightFields(new HighlightBuilder.Field("description").preTags(preTags).postTags(postTags))
.withPageable(pageable)
.build();
AggregatedPage<Stu> stus = esTemplate.queryForPage(searchQuery, Stu.class, new SearchResultMapper() {
@Override
public <T> AggregatedPage<T> mapResults(SearchResponse searchResponse, Class<T> aClass, Pageable pageable) {

SearchHits hits = searchResponse.getHits();
List<Stu> stuList = new ArrayList<>();
for (SearchHit searchHit : hits){
HighlightField highlightField = searchHit.getHighlightFields().get("description");
String description = highlightField.getFragments()[0].toString();
Object stuId = searchHit.getSourceAsMap().get("stuId");
searchHit.getSourceAsMap().get("name");
Integer age = (Integer) searchHit.getSourceAsMap().get("age");
Object money = searchHit.getSourceAsMap().get("money");
searchHit.getSourceAsMap().get("sign");
Stu stu = new Stu();
stu.setDescription(description);
stu.setStuId(Long.valueOf(stuId.toString()));
stu.setAge(age);
stu.setMoney(Float.valueOf(money.toString()));
stuList.add(stu);
}
if (stuList.size() > 0) {
return new AggregatedPageImpl<>((List<T>)stuList);
}
return null;
}
});
System.out.println(stus.getTotalPages());
System.out.println(stus.getContent());
}

（6）搜索内容实现排序

@Test
public void searchStuDocForSort() {

String preTags = "<font color='red'>";
String postTags = "</font>";
Pageable pageable = PageRequest.of(0, 2);

SortBuilder sortBuilder = new FieldSortBuilder("money");
sortBuilder.order(SortOrder.ASC);
NativeSearchQuery searchQuery = new NativeSearchQueryBuilder()
.withQuery(QueryBuilders.matchQuery("description", "man"))
.withHighlightFields(new HighlightBuilder.Field("description").preTags(preTags).postTags(postTags))
.withSort(sortBuilder)
.withPageable(pageable)
.build();
AggregatedPage<Stu> stus = esTemplate.queryForPage(searchQuery, Stu.class);
System.out.println(stus.getTotalPages());
System.out.println(stus.getContent());
}