java es获取最新的一条数据

以下是使用 Java API 从 Elasticsearch 中获取最新的一条数据的示例代码：

SearchRequest searchRequest = new SearchRequest("your_index");
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
searchSourceBuilder.query(QueryBuilders.matchAllQuery());
searchSourceBuilder.sort("your_timestamp_field", SortOrder.DESC);
searchSourceBuilder.size(1);
searchRequest.source(searchSourceBuilder);

RestHighLevelClient client = new RestHighLevelClient(
        RestClient.builder(new HttpHost("localhost", 9200, "http")));

SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
SearchHits hits = searchResponse.getHits();
SearchHit[] searchHits = hits.getHits();
if (searchHits.length > 0) {
    String jsonString = searchHits[0].getSourceAsString();
    // 处理获取到的最新的文档
}

client.close();

请将 `your_index` 替换为您的索引名称，`your_timestamp_field` 替换为您存储时间戳的字段名称。这个查询将会按照时间戳倒序排列所有文档，并返回最新的一条。您可以在 `if (searchHits.length > 0)` 中处理获取到的最新的文档。