用过es的朋友应该都了解es的分页模式总共有两种，一种是from,size模式，也就是常说的浅分页，这种分页模式使用起来很简单，和mysql的十分类似，但是这种方式的最大弊端是，在集群模式下，如果查询的分页数很深，很容易造成查询效率极慢甚至内存的异出的问题，解决这个问题就要提到深分页，深分页的大概思路是每一页查询会给你返回一个scrollId，类似于一个游标，记录本次查询的位置，下次使用这个有游标再去查下一页的数据，所有不会出现跨度大，查询数据多导致溢出的问题，但是它也有一个弊端就是不支持跳页。还有就是es默认的查询（也就是不加from,size）是会返回第一页10条数据，而我最近正在使用es做一个导出的功能，那么很明显默认返回一页的数据不是很友好，所有正好使用深分页可以解决。废话少说，上代码，先说下from,size的方法，这里都是使用HighLevelRestClient实现的。
// comprehensiveQueryEventVO是我封装的一个查询条件实体对象，这里是封装查询条件
private SearchSourceBuilder getSearchSourceBuilder(ComprehensiveQueryEventVO comprehensiveQueryEventVO){SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();if (comprehensiveQueryEventVO.getPageNum() != null && comprehensiveQueryEventVO.getPageSize() != null) {sourceBuilder.from((comprehensiveQueryEventVO.getPageNum()-1)*comprehensiveQueryEventVO.getPageSize());sourceBuilder.size(comprehensiveQueryEventVO.getPageSize());}
SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();if (comprehensiveQueryEventVO.getPageNum() != null && comprehensiveQueryEventVO.getPageSize() != null) {sourceBuilder.from((comprehensiveQueryEventVO.getPageNum()-1)*comprehensiveQueryEventVO.getPageSize());sourceBuilder.size(comprehensiveQueryEventVO.getPageSize());}// 拼接动态查询条件if (StringUtils.isNotEmpty(comprehensiveQueryEventVO.getEventCode())) {boolBuilder.must(QueryBuilders.termQuery("eventCode", comprehensiveQueryEventVO.getEventCode()));}return sourceBuilder;
}/*** 查询封装，带分页* @param searchSourceBuilder* @param pageNum* @param pageSize* @param s* @param <T>* @return* @throws IOException*/public <T> PageInfo<T> search(SearchSourceBuilder searchSourceBuilder, int pageNum, int pageSize, Class<T> s) throws Exception {Document declaredAnnotation = (Document )s.getDeclaredAnnotation(Document.class);if(declaredAnnotation == null){throw new Exception(String.format("class name: %s can not find Annotation [Document], please check", s.getName()));}String indexName = declaredAnnotation.index();SearchRequest searchRequest = new SearchRequest(indexName);searchRequest.source(searchSourceBuilder);SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);SearchHits hits = searchResponse.getHits();JSONArray jsonArray = new JSONArray();for (SearchHit hit : hits) {String sourceAsString = hit.getSourceAsString();JSONObject jsonObject = JSON.parseObject(sourceAsString);jsonArray.add(jsonObject);}log.info("返回总数为：" + hits.getTotalHits());int total = (int)hits.getTotalHits().value;// 封装分页List<T> list = jsonArray.toJavaList(s);PageInfo<T> page = new PageInfo<>();page.setList(list);page.setPageNum(pageNum);page.setPageSize(pageSize);page.setTotal(total);page.setPages(total== 0 ? 0: (total%pageSize == 0 ? total / pageSize : (total / pageSize) + 1));page.setHasNextPage(page.getPageNum() < page.getPages());return page;}下面看下深分页如何实现，深分页做的导出查询，所以不需要返回分页信息，只需要返回一个集合，但是集合内部的查询是使用深分页的方式一页一页查询的，所以注意查询条件中不要封装from, to参数
/*** 查询封装，返回集合--不分页* @param searchSourceBuilder* @param s* @param <T>* @return* @throws IOException*/public <T> List<T> search(SearchSourceBuilder searchSourceBuilder, Class<T> s) throws Exception {Document declaredAnnotation = (Document)s.getDeclaredAnnotation(Document.class);if(declaredAnnotation == null){throw new Exception(String.format("class name: %s can not find Annotation [Document], please check", s.getName()));}String indexName = declaredAnnotation.index();final Scroll scroll = new Scroll(TimeValue.timeValueMinutes(1L));SearchRequest searchRequest = new SearchRequest(indexName);searchRequest.source(searchSourceBuilder);searchRequest.scroll(scroll);SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);String scrollId = searchResponse.getScrollId();SearchHit[] searchHits = searchResponse.getHits().getHits();long totalHits = searchResponse.getHits().getTotalHits().value;log.info("es查询集合总数为{}", totalHits);JSONArray jsonArray = new JSONArray();while (searchHits != null && searchHits.length > 0) {for (SearchHit hit : searchResponse.getHits().getHits()) {String sourceAsString = hit.getSourceAsString();JSONObject jsonObject = JSON.parseObject(sourceAsString);jsonArray.add(jsonObject);}SearchScrollRequest scrollRequest = new SearchScrollRequest(scrollId);scrollRequest.scroll(scroll);searchResponse = restHighLevelClient.scroll(scrollRequest, RequestOptions.DEFAULT);scrollId = searchResponse.getScrollId();searchHits = searchResponse.getHits().getHits();}// 清除滚屏if (scrollId != null) {ClearScrollRequest clearScrollRequest = new ClearScrollRequest();clearScrollRequest.addScrollId(scrollId);ClearScrollResponse clearScrollResponse = restHighLevelClient.clearScroll(clearScrollRequest, RequestOptions.DEFAULT);boolean succeeded = clearScrollResponse.isSucceeded();}// 封装集合List<T> list = jsonArray.toJavaList(s);return list;}