Question

我正在呼叫分页服务我可以使用以下代码遍历所有分页集合：

Pageable pageable = PageRequest.of(0,100);
Page<Event> events = eventsService.getEventsPage(pageable);
while(!events.isLast()) {
    doStuff(events)
    events = eventsService.getEventsPage(events.nextPageable())
}
doStuff(events) // rest of events

有没有更优雅的解决方案？我需要分页，因为否则，系统将耗尽内存。

Answer 1

我会使用Slice（由Page继承的getContent()。

List <T> getContent()

将页面内容返回为List。

Pageable pageable = PageRequest.of(0,100);
Page<Event> events = eventsService.getEventsPage(pageable);
List<Event> eventList = events.getContent();
for (Event event : eventList) {
    // do stuff 
}

Answer 2

我觉得不得不陈述两次服务电话和doStuff有点脆弱。您可以利用以下事实：如果当前页面已经是最后一页，则nextPageable()将为您提供unpaged单身。

Pageable pageable = PageRequest.of(0,100);
do {
    Page<Event> events = eventsService.getEventsPage(pageable);
    doStuff(events)
    pageable = events.nextPageable();
} while(pageable.isPaged())

这里是nextPageable()的文档。

 /**
 * Returns the {@link Pageable} to request the next {@link Slice}. Can be {@link Pageable#unpaged()} in case the
 * current {@link Slice} is already the last one. Clients should check {@link #hasNext()} before calling this method.
 *
 * @return
 * @see #nextOrLastPageable()
 */
Pageable nextPageable();

使用Spring数据和分页遍历所有结果

2 个答案: