ES使用游标查询数据

        
        CountRequest countRequest = new CountRequest();
        countRequest.types("TYPE");
        countRequest.indices("INDEX");
        // 拼接查询条件
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        countRequest.source(searchSourceBuilder);
        long count = restHighLevelClient.count(countRequest, RequestOptions.DEFAULT);
        if (count > 300000) {
            throw new RuntimeException("下载数量不可超过30W条");
        }
        // 采用游标查询
        searchSourceBuilder.size(10000);
        SearchRequest searchRequest = new SearchRequest("INDEX").types("TYPE");
        searchRequest.source(searchSourceBuilder);
        Scroll scroll = new Scroll(TimeValue.timeValueMinutes(5L));
        searchRequest.scroll(scroll);
        SearchResponse searchResponse = restHighLevelClient.search(request, RequestOptions.DEFAULT);
        String scrollId = searchResponse.getScrollId();
        SearchHit[] searchHits = searchResponse.getHits().getHits();
        List searchHitList = new ArrayList<>(Arrays.asList(searchHits));
        while (true) {
            if (searchHits.length == 0) {
                break;
            }
            SearchScrollRequest scrollRequest = new SearchScrollRequest(scrollId);
            scrollRequest.scroll(scroll);
            searchResponse = restHighLevelClient.scroll(searchScrollRequest, RequestOptions.DEFAULT);
            scrollId = searchResponse.getScrollId();
            searchHits = searchResponse.getHits().getHits();
            // 导出也可以写在此处，在导出大批量的数据时，JVM内存有限，使用SXSSF进行导出，防止JVM内存撑爆
            searchHitList.addAll(Arrays.asList(searchHits));
        }
        // 清除滚动ID
        esService.clearScroll(scrollId);
        // 数据转换
        // 对结果进行排序
        // 下载

可以使用 SXSSFWorkbook 进行大批量导出，获取一部分数据导出一部分，减缓JVM压力