Elastic Search（ES）Java 入门实操（2）搜索代码

上篇解释了 ES 的基本概念和分词器。Elastic Search （ES）Java 入门实操（1）下载安装、概念-CSDN博客

Elastic Search（ES）Java 入门实操（3）数据同步-CSDN博客

这篇主要演示 Java 整合 ES进行数据搜索。

ES 实现搜索接口

首先根据 MySQL 字段，在 ES 创建索引。

create table mydb
(id          int auto_increment comment '序号'primary key,title       varchar(20)                        not null comment '标题',content     text                               not null comment '内容',cretateTime datetime default CURRENT_TIMESTAMP not null comment '创建时间',updateTime  datetime default CURRENT_TIMESTAMP not null on update CURRENT_TIMESTAMP comment '更新时间',isDelete    tinyint  default 0                 not null comment '是否删除'
)comment '文章' collate = utf8mb4_unicode_ci;

PUT article_1
{"aliases": {  #别名"article": {}},"mappings": {"properties": {"title": {"type": "text", #字段类型"analyzer": "ik_max_word",#插入时分词方式"search_analyzer": "ik_smart", #查询时分词方式"fields": { #字段配置，子字段"keyword": { "type": "keyword", #精确匹配"ignore_above": 256 #超过 256 字符就忽略查询}}},"content": {"type": "text","analyzer": "ik_max_word","search_analyzer": "ik_smart","fields": {"keyword": {"type": "keyword","ignore_above": 256}}},"createTime": {"type": "date"},"updateTime": {"type": "date"},"isDelete": {"type": "keyword"}}}
}

引入 spring-data-elasticsearch 依赖

需要注意版本号一定要兼容

Spring Data Elasticsearch - Reference Documentation

这里使用的是 7.17版本，所以选择相近的 4.4.x版本的依赖，同样的 springboot 的版本也得严格对应。Maven Repository: org.springframework.data » spring-data-elasticsearch » 4.4.7 (mvnrepository.com)

下面的报错就是版本不对，需要把springboot 改为 2.7+，

java.lang.NoSuchFieldError: INDEX_CONTENT_TYPE

<!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-elasticsearch -->
<dependency><groupId>org.springframework.data</groupId><artifactId>spring-data-elasticsearch</artifactId><version>4.4.7</version>
</dependency>

启动 springboot，有调用的日志

给 ES 索引创建实体类

/*** ES 实体类* document 注解是将Java 对象映射到 Elasticsearch 索引和类型中*/
@Document(indexName = "article")
@Data
public class ArticleEsDto implements Serializable {private static final String DATE_TIME_PATTERN = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";/*** id* 需要打上 id 注解，指定 ES 中存储的 id 是唯一字段* 如果新增是不传入，则 ES 会自动生成*/@Idprivate long id;/*** 标题*/private String title;/*** 内容*/private String content;/*** 创建时间*/@Field(index = false, store = true,type = FieldType.Date,format = {},pattern = DATE_TIME_PATTERN)private Date createTime;/*** 更新时间* Field：这是一个MyBatis-Plus注解，用于标注该字段在数据库表中的对应关系。* 其中，index = false表示该字段不在数据库表的索引中，* store = true表示该字段在数据库表的存储中，* type = FieldType.Date表示该字段的类型为Date，* format = {}表示该字段的格式为空，* pattern = DATE_TIME_PATTERN表示该字段的日期时间格式为DATE_TIME_PATTERN。*/@Field(index = false, store = true,type = FieldType.Date,format = {},pattern = DATE_TIME_PATTERN)private Date updateTime;/*** 是否删除*/private Integer isDelete;private static final long serialVersionUID = 1L;
}

第一种方式

elasticsearch Respository，新建类继承该类，默认提供了简单的增删改查方法，多用于可以预期的，相对不复杂的查询

@NoRepositoryBean
public interface CrudRepository<T, ID> extends Repository<T, ID> {<S extends T> S save(S entity);<S extends T> Iterable<S> saveAll(Iterable<S> entities);Optional<T> findById(ID id);boolean existsById(ID id);Iterable<T> findAll();Iterable<T> findAllById(Iterable<ID> ids);long count();void deleteById(ID id);void delete(T entity);void deleteAllById(Iterable<? extends ID> ids);void deleteAll(Iterable<? extends T> entities);void deleteAll();
}

/*** ES 的控制层* 继承 ElasticsearchRepository 即可*/
public interface ArticleEsDao extends ElasticsearchRepository<ArticleEsDto, Long> {// 这里可以扩展一些自定义方法// 例如：根据标题模糊查询List<ArticleEsDto> findByTitle(String title);}

新增测试

//注入接口@Resourceprivate ArticleEsDao articleEsDao;//测试新增@Testvoid EsTest1(){//创建实体对象并添加属性ArticleEsDto articleEsDto = new ArticleEsDto();articleEsDto.setId(1L);articleEsDto.setTitle("青花瓷");articleEsDto.setContent("天青色等烟雨而我在等你");articleEsDto.setCreateTime(new Date());articleEsDto.setUpdateTime(new Date());articleEsDto.setIsDelete(0);//调用方法保存articleEsDao.save(articleEsDto);System.out.println(articleEsDto.getId());}

dev tools 查看

GET article/_search/

自定义方法测试

我们在上面创建接口的时候创建了一个根据标题查询的方法

    @Testvoid EsTest2(){List<ArticleEsDto> articleEsDtos = articleEsDao.findByTitle("青花瓷");System.out.println(articleEsDtos);}

第二种方式

spring 默认提供了操作 ES 的客户端对象 ElasticSearchRestTemplate，同样提供了增删改查，更加灵活，适用于更加复杂的操作，返回结果更加完整，但是需要自己解析。

    @Resourceprivate ElasticsearchRestTemplate elasticsearchRestTemplate;

提示，在编写查询条件以及处理数据时，可以先在 Dev Tools 中执行一下查询，没问题之后再进行代码层面的条件编写。

查询 DSL

官方文档：Query and filter context | Elasticsearch Guide [8.14] | Elastic

查询模式：Boolean query | Elasticsearch Guide [8.14] | Elastic

GET /_search
{"query": {  "bool": {  //组合条件"must": [ //必须匹配{ "match":  // 模糊匹配{ "title":   "Search"        }},{ "match": { "content": "Elasticsearch" }}],"filter": [ //{ "term": //精确匹配 { "status": "published" }},{ "range": //范围匹配 { "publish_date": { "gte": "2015-01-01" }}}]}}
}

除了 must ，filter，还有 must_not，必须不存在才能匹配，should，至少有多少个条件相符才匹配，同时还有一个参数 minimum_should_match 满足最小的条件数，比如 1，至少满足一个条件才能查询到，比如标题和描述存在一个就可以返回结果。

POST _search
{"query": {"bool" : {"must" : {"term" : { "user.id" : "kimchy" }},"filter": {"term" : { "tags" : "production" }},"must_not" : {"range" : {"age" : { "gte" : 10, "lte" : 20 }}},"should" : [{ "term" : { "tags" : "env1" } },{ "term" : { "tags" : "deployed" } }],"minimum_should_match" : 1,"boost" : 1.0}}
}

需要注意的是，通过模糊查询之后，查询结果中有一个参数是 max_score，表示这条数据和搜索条件的最高匹配度。

在 Java 中编写查询条件以及处理查询的数据。

主要使用到的 API

//查询条件构造器
BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();//排序条件构造器
SortBuilder<?> sortBuilder = SortBuilders.scoreSort();//分页
PageRequest pageRequest = PageRequest.of((int) current, (int) pageSize);//组合查询条件
NativeSearchQuery searchQuery = new NativeSearchQueryBuilder().withQuery(boolQueryBuilder).withPageable(pageRequest).withSorts(sortBuilder).build();
//调用 elasticsearchRestTemplate 查询
SearchHits<PostEsDTO> searchHits = elasticsearchRestTemplate.search(searchQuery, PostEsDTO.class);

完整代码

/*** 从 es 查询数据*/
@Service
public class ArticleEsManager {@Resourceprivate ArticleMapper articleMapper;@Resourceprivate ElasticsearchRestTemplate elasticsearchRestTemplate;public Page<Article> searchByEs(ArticleQueryRequest articleQueryRequest) {//提取查询参数Long id = articleQueryRequest.getId();String searchText = articleQueryRequest.getSearchText();String content = articleQueryRequest.getContent();String title = articleQueryRequest.getTitle();//设置分页参数，起始页为 0int current = articleQueryRequest.getCurrent() -1 ;int pageSize = articleQueryRequest.getPageSize();String sortField = articleQueryRequest.getSortField();String sortOrder = articleQueryRequest.getSortOrder();//构建布尔查询，创建 boolqueryBuilder，用于后续查询条件构建BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();//过滤查询条件//过滤掉被逻辑删除的 term 是精确匹配boolQueryBuilder.filter(QueryBuilders.termQuery("isDelete",0));//id必须精确匹配if(id!=null){boolQueryBuilder.filter(QueryBuilders.termQuery("id",id));}//模糊查询，按照查询词（关键词）检索if(StringUtils.isNotEmpty(searchText)){boolQueryBuilder.should(QueryBuilders.matchQuery("title",searchText));boolQueryBuilder.should(QueryBuilders.matchQuery("content",searchText));//设置至少多少匹配才进行查询boolQueryBuilder.minimumShouldMatch(1);}//根据标题检索if(StringUtils.isNotEmpty(title)){boolQueryBuilder.should(QueryBuilders.matchQuery("title",title));boolQueryBuilder.minimumShouldMatch(1);}//根据内容检索if(StringUtils.isNotEmpty(content)){boolQueryBuilder.should(QueryBuilders.matchQuery("content",searchText));//设置至少多少匹配才进行查询boolQueryBuilder.minimumShouldMatch(1);}//进行排序//对查询结果的分数进行排序SortBuilder<?> sortBuilder = SortBuilders.scoreSort();if (StringUtils.isNotEmpty(sortField) && StringUtils.isNotEmpty(sortOrder)){sortBuilder = SortBuilders.fieldSort(sortField);sortBuilder.order(CommonConstant.SORT_ORDER_ASC.equals(sortOrder) ? SortOrder.ASC:SortOrder.DESC);}//分页PageRequest pageRequest = PageRequest.of(current, pageSize);//构造查询NativeSearchQuery searchQuery = new NativeSearchQueryBuilder().withQuery(boolQueryBuilder).withPageable(pageRequest).withSorts(sortBuilder).build();//调用 elasticsearchRestTemplate 执行查询SearchHits<ArticleEsDto> searchHits = elasticsearchRestTemplate.search(searchQuery, ArticleEsDto.class);System.out.println(searchHits);Page<Article> page = new Page<>();page.setTotal(searchHits.getTotalHits());//新建集合存储文章List<Article> resourceList = new ArrayList<>();//处理结果，判断是否有搜索结果if(searchHits.hasSearchHits()){//获取结果列表List<SearchHit<ArticleEsDto>> searchHits1 = searchHits.getSearchHits();System.out.println(searchHits1);//获取结果的id，使用id在数据库中查询List<Long> ids = searchHits1.stream().map(searchHit -> searchHit.getContent().getId()).collect(Collectors.toList());List<Article> articles = articleMapper.selectBatchIds(ids);//将查询结果与数据库查询结果进行匹配if (CollectionUtils.isNotEmpty(articles)) {//将查询结果与数据库查询结果进行匹配Map<Long, List<Article>> collect = articles.stream().collect(Collectors.groupingBy(Article::getId));//遍历文章idarticles.forEach(articleId -> {if(collect.containsKey(articleId)){resourceList.add(collect.get(articleId).get(0));}else{// 从 es 清空 db 已物理删除的数据String delete = elasticsearchRestTemplate.delete(String.valueOf(articleId), ArticleEsDto.class);}});}}page.setRecords(resourceList);return page;}
}

成功查询到数据

完整代码

/*** 从 es 查询数据*/
@Service
public class ArticleEsManager {@Resourceprivate ArticleMapper articleMapper;@Resourceprivate ElasticsearchRestTemplate elasticsearchRestTemplate;public Page<Article> searchByEs(ArticleQueryRequest articleQueryRequest) {//提取查询参数Long id = articleQueryRequest.getId();String searchText = articleQueryRequest.getSearchText();String content = articleQueryRequest.getContent();String title = articleQueryRequest.getTitle();//设置分页参数，起始页为 0int current = articleQueryRequest.getCurrent() -1 ;int pageSize = articleQueryRequest.getPageSize();String sortField = articleQueryRequest.getSortField();String sortOrder = articleQueryRequest.getSortOrder();//构建布尔查询，创建 boolqueryBuilder，用于后续查询条件构建BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();//过滤查询条件//过滤掉被逻辑删除的 term 是精确匹配boolQueryBuilder.filter(QueryBuilders.termQuery("isDelete",0));//id必须精确匹配if(id!=null){boolQueryBuilder.filter(QueryBuilders.termQuery("id",id));}//模糊查询，按照查询词（关键词）检索if(StringUtils.isNotEmpty(searchText)){boolQueryBuilder.should(QueryBuilders.matchQuery("title",searchText));boolQueryBuilder.should(QueryBuilders.matchQuery("content",searchText));//设置至少多少匹配才进行查询boolQueryBuilder.minimumShouldMatch(1);}//根据标题检索if(StringUtils.isNotEmpty(title)){boolQueryBuilder.should(QueryBuilders.matchQuery("title",title));boolQueryBuilder.minimumShouldMatch(1);}//根据内容检索if(StringUtils.isNotEmpty(content)){boolQueryBuilder.should(QueryBuilders.matchQuery("content",searchText));//设置至少多少匹配才进行查询boolQueryBuilder.minimumShouldMatch(1);}//进行排序//对查询结果的分数进行排序SortBuilder<?> sortBuilder = SortBuilders.scoreSort();if (StringUtils.isNotEmpty(sortField) && StringUtils.isNotEmpty(sortOrder)){sortBuilder = SortBuilders.fieldSort(sortField);sortBuilder.order(CommonConstant.SORT_ORDER_ASC.equals(sortOrder) ? SortOrder.ASC:SortOrder.DESC);}//分页PageRequest pageRequest = PageRequest.of(current, pageSize);//构造查询NativeSearchQuery searchQuery = new NativeSearchQueryBuilder().withQuery(boolQueryBuilder).withPageable(pageRequest).withSorts(sortBuilder).build();//调用 elasticsearchRestTemplate 执行查询SearchHits<ArticleEsDto> searchHits = elasticsearchRestTemplate.search(searchQuery, ArticleEsDto.class);System.out.println(searchHits);Page<Article> page = new Page<>();page.setTotal(searchHits.getTotalHits());//新建集合存储文章List<Article> resourceList = new ArrayList<>();//处理结果，判断是否有搜索结果if(searchHits.hasSearchHits()){//获取结果列表List<SearchHit<ArticleEsDto>> searchHits1 = searchHits.getSearchHits();System.out.println(searchHits1);//获取结果的id，使用id在数据库中查询List<Long> ids = searchHits1.stream().map(searchHit -> searchHit.getContent().getId()).collect(Collectors.toList());List<Article> articleList = articleMapper.selectBatchIds(ids);//将查询结果与数据库查询结果进行匹配if (CollectionUtils.isNotEmpty(articleList)) {//将查询结果与数据库查询结果进行匹配Map<Long, List<Article>> collect = articleList.stream().collect(Collectors.groupingBy(Article::getId));//遍历文章idids.forEach(articleId -> {if(collect.containsKey(articleId)){resourceList.add(collect.get(articleId).get(0));}else{// 从 es 清空 db 已物理删除的数据String delete = elasticsearchRestTemplate.delete(String.valueOf(articleId), ArticleEsDto.class);}});}}//设置到分页里page.setRecords(resourceList);return page;}