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。
代码语言：javascript复制// 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
代码语言：javascript复制/**
* 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;
}好了，今天的分享就到这里，希望对你有帮助
