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一、背景

es索引有一个文档CourseIndex，下面是示意:

creatorId	grade	subject	name	no
1002	2	70	英语听力课程一	N00232DS9
1004	3	80	数学口算课程	N00209DK7
1003	4	80	物理竞赛课程	N00642XS2
1002	2	80	英语听力课程二	N00432WS3
1002	2	90	英语听力课程三	N002312DP5

在搜索的时候，搜索条件包括creatorId列表，grade列表，subject列表等，且它们不是固定的字典，而是从文档CourseIndex的已有数据中获取。

假使上面的数据，搜索条件分别是：

creatorId列表

• 1002
• 1003
• 1004

grade列表

• 2
• 3
• 4

subject列表

• 70
• 80
• 90

总结一下需求，对es文档的数据进行桶bucket排序，以达到去重效果。

下面将介绍如何使用spring-data-elasticsearch 3.2.4实现对指定字段的聚合搜索。

pom.xml引入jar包

    <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-elasticsearch</artifactId></dependency><dependency><groupId>org.springframework.data</groupId><artifactId>spring-data-elasticsearch</artifactId><version>3.2.4.RELEASE</version></dependency>

二、CourseIndexAggrService.java

import lombok.RequiredArgsConstructor;
import org.elasticsearch.index.query.BoolQueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.aggregations.Aggregation;
import org.elasticsearch.search.aggregations.AggregationBuilders;
import org.elasticsearch.search.aggregations.bucket.terms.ParsedLongTerms;
import org.elasticsearch.search.aggregations.bucket.terms.Terms;
import org.elasticsearch.search.aggregations.bucket.terms.TermsAggregationBuilder;
import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
import org.springframework.data.elasticsearch.core.aggregation.AggregatedPage;
import org.springframework.data.elasticsearch.core.query.NativeSearchQueryBuilder;
import org.springframework.stereotype.Component;import java.util.ArrayList;
import java.util.List;/*** @author xxx*/
@Component
@RequiredArgsConstructor
public class CourseIndexAggrService {private final ElasticsearchRestTemplate elasticsearchRestTemplate;private final CommonConfig commonConfig;private static final String UNIQUE_FIELD = "unique_field";// 需要进行桶排序的字段public static final String CREATOR_ID = "creatorId";public static final String GRADE = "grade";public static final String SUBJECT = "subject";public List<String> findUniqueField(String uniqueField) {NativeSearchQueryBuilder queryBuilder = new NativeSearchQueryBuilder();BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();//TODO 这里boolQueryBuilder是一个空的查询条件// 过滤掉已逻辑删除的记录 // boolQueryBuilder.filter(QueryBuilders.termQuery("deleted", 0));queryBuilder.withQuery(boolQueryBuilder);TermsAggregationBuilder termsAgg = AggregationBuilders.terms(UNIQUE_FIELD).field(uniqueField);queryBuilder.addAggregation(termsAgg);// idx_courseIndex是索引名queryBuilder.withIndices("idx_courseIndex");// CourseIndex是es文档类，见下文AggregatedPage<CourseIndex> resultPage = elasticsearchRestTemplate.queryForPage(queryBuilder.build(), CourseIndex.class);Aggregation aggregation = resultPage.getAggregation(UNIQUE_FIELD);ParsedLongTerms terms = (ParsedLongTerms) aggregation;// 获取桶final List<? extends Terms.Bucket> buckets = terms.getBuckets();// 提取唯一值List<String> uniqueUserIds = new ArrayList<>();for (Terms.Bucket bucket : buckets) {uniqueUserIds.add(bucket.getKeyAsString());}return uniqueUserIds;}
}

三、CourseIndex.java

这里略去了无关本文的字段。

import lombok.Data;
import org.springframework.data.elasticsearch.annotations.Document;
import org.springframework.data.elasticsearch.annotations.Field;
import org.springframework.data.elasticsearch.annotations.FieldType;import javax.persistence.Id;
import java.io.Serializable;
import java.util.Set;/*** 课程索引.* <p>* 索引检索条件，并非所有的字段* </p>** @author xxx*/
@Data
@Document(indexName = "#{commonConfig.courseIdx}", type = "_doc", shards = 1, refreshInterval = "-1")
public class CourseIndex implements Serializable {@Idprivate String id;/*** 课程或讲次编号*/@Field(type = FieldType.Keyword)private String no;/*** 创建者ID*/@Field(type = FieldType.Long)private long creatorId;/*** 课程或讲次名称*/@Field(type = FieldType.Text)private String name;/*** 科目*/@Field(type = FieldType.Integer)private int subject;/*** 年级*/@Field(type = FieldType.Integer)private int grade;
}

四、使用

// 查询创建者creatorId列表
final List<Long> userIds = courseIndexAggrService.findUniqueField(CREATOR_ID).stream().map(v -> Long.parseLong(v)).collect(Collectors.toList());// 查询年级grade列表
final List<Integer> grades = courseIndexAggrService.findUniqueField(GRADE).stream().map(v -> Integer.parseInt(v)).collect(Collectors.toList());// 查询科目subject列表
final List<Integer> subjects = courseIndexAggrService.findUniqueField(SUBJECT).stream().map(v -> Integer.parseInt(v)).collect(Collectors.toList());