可以使用Elasticsearch的聚合（Aggregation）功能来实现查询某一个字段的出现次数。以下是使用JestClient进行查询的Java代码示例：

```java import io.searchbox.client.JestClient; import io.searchbox.core.Search; import io.searchbox.core.SearchResult; import io.searchbox.params.Parameters; import org.elasticsearch.index.query.QueryBuilders; import org.elasticsearch.search.aggregations.AggregationBuilders; import org.elasticsearch.search.aggregations.bucket.terms.Terms; import org.elasticsearch.search.aggregations.metrics.sum.Sum; import java.io.IOException; public class ElasticsearchQuery { public static void main(String[] args) throws IOException { // 创建JestClient实例 JestClient jestClient = JestClientFactoryUtil.getJestClient(); // 构建查询语句 Search search = new Search.Builder("{ " + " "query": { " + " "match_all": {} " + " }, " + " "aggs": { " + " "count_by_field": { " + " "terms": { " + " "field": "field_name.keyword" " + // 要查询的字段名 " } " + " } " + " } " + "}