SpringBoot ElasticSearch 聚合排序

Spring Boot和Elasticsearch的集成主要涉及使用Spring Data Elasticsearch库。Elasticsearch是一个分布式搜索引擎，它提供了丰富的RESTful API，用于索引、搜索和分析大量数据。

在Spring Boot中，你可以使用Spring Data Elasticsearch来简化与Elasticsearch的交互。Spring Data Elasticsearch提供了对Elasticsearch的高级查询、聚合和其他操作的支持。

聚合（Aggregation）：聚合是一种在Elasticsearch中进行数据分析的方式。它允许你对数据集执行各种统计、计算和分析操作。聚合框架支持的一些常见聚合类型包括：

BucketAggregations：将文档分配到不同的"桶"中，类似于SQL中的GROUP BY。常见的桶聚合包括terms、date histogram等。

MetricAggregations：计算文档字段的度量值，如求和、平均值、最大值、最小值等。

PipelineAggregations：允许你在其他聚合的结果上执行进一步的操作，类似于数据流管道。

Spring Data Elasticsearch中的聚合支持： Spring Data Elasticsearch通过ElasticsearchTemplate或ElasticsearchRepository接口提供对Elasticsearch聚合的支持。你可以使用NativeSearchQueryBuilder构建查询，然后使用addAggregation方法添加各种聚合。

java 复制代码

import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.aggregations.Aggregation;
import org.elasticsearch.search.aggregations.AggregationBuilders;
import org.elasticsearch.search.aggregations.Aggregations;
import org.elasticsearch.search.aggregations.bucket.terms.ParsedStringTerms;
import org.elasticsearch.search.aggregations.bucket.terms.Terms;
import org.elasticsearch.search.aggregations.bucket.terms.TermsAggregationBuilder;
import org.elasticsearch.search.aggregations.metrics.ValueCountAggregationBuilder;
import org.elasticsearch.search.aggregations.pipeline.BucketHelpers;
import org.elasticsearch.search.aggregations.pipeline.BucketSortPipelineAggregationBuilder;
import org.elasticsearch.search.sort.FieldSortBuilder;
import org.elasticsearch.search.sort.SortOrder;
import org.jeecg.modules.mark.common.es.entity.AudioMarkInfo;
import org.junit.jupiter.api.Test;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
import org.springframework.data.elasticsearch.core.SearchHits;
import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
import org.springframework.data.elasticsearch.core.query.NativeSearchQueryBuilder;

@SpringBootTest
public class ElasticSearchTest {

    @Autowired
    private ElasticsearchRestTemplate restTemplate;

    @Test
    public void count() {

        String indexName = "app_student_1";

        List<String> ids = new ArrayList<>();
        ids.add("1");
        ids.add("2");

        NativeSearchQueryBuilder query = new NativeSearchQueryBuilder();
        query.withQuery(QueryBuilders.termsQuery("id", ids));

        TermsAggregationBuilder group = AggregationBuilders.terms("group").field("id");

        // 计数
        ValueCountAggregationBuilder counts = AggregationBuilders.count("count").field("id");
        group.subAggregation(counts);

        // 统计字段排序
        group.subAggregation(new BucketSortPipelineAggregationBuilder("orderType",
                Collections.singletonList(new FieldSortBuilder("count").order(SortOrder.DESC)))
                .gapPolicy(BucketHelpers.GapPolicy.INSERT_ZEROS));

        SearchHits<AudioMarkInfo> search = restTemplate.search(query.build(), AudioMarkInfo.class,
                IndexCoordinates.of(indexName));

        Aggregations aggregations = search.getAggregations();

        ParsedStringTerms terms = aggregations.get("group");

        List<? extends Terms.Bucket> buckets = terms.getBuckets();

        for (Terms.Bucket bucket : buckets) {
            String id = bucket.getKeyAsString();
            long count = bucket.getDocCount();

            for (Aggregation list : bucket.getAggregations().asList()) {
                // TODO:
            }
        }

    }

}