java获取elasticsearch中某个字段的所有值

import org.elasticsearch.action.search.SearchRequest;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.RequestOptions;
import org.elasticsearch.client.RestClient;
import org.elasticsearch.client.RestHighLevelClient;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.builder.SearchSourceBuilder;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class ElasticsearchFieldValuesExample {

    public static void main(String[] args) {
        // 创建Elasticsearch客户端
        RestHighLevelClient client = new RestHighLevelClient(
                RestClient.builder("localhost:9200"));

        // 构建搜索请求
        SearchRequest searchRequest = new SearchRequest("index_name");
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        searchSourceBuilder.query(QueryBuilders.matchAllQuery());
        searchSourceBuilder.size(0); // 设置为0，只返回聚合结果，不返回文档
        searchSourceBuilder.aggregation(
                AggregationBuilders.terms("field_values").field("field_name").size(1000)); // 设置聚合字段和聚合大小
        searchRequest.source(searchSourceBuilder);

        try {
            // 执行搜索请求
            SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);

            // 解析聚合结果
            Terms termsAggregation = searchResponse.getAggregations().get("field_values");
            List<String> fieldValues = new ArrayList<>();
            for (Terms.Bucket bucket : termsAggregation.getBuckets()) {
                String fieldValue = bucket.getKeyAsString();
                fieldValues.add(fieldValue);
            }

            // 输出结果
            System.out.println("Field values: " + fieldValues);

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭Elasticsearch客户端
            try {
                client.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}