阿里巴巴Java开发手册:java
@Override public PageInfo<HdQueryVo> getRecordsByView(int pageNo, int pageSize) { PageHelper.startPage(pageNo,pageSize); List<HdQueryVo> hdQueryVosByView = actionMapper.getActionByView(); List<HdQueryVo> hdQueryVos = new ArrayList<>(); for (HdQueryVo hdQueryVo : hdQueryVosByView) { HdQueryVo hdQueryVoSingle = new HdQueryVo(); hdQueryVoSingle.setHdId(hdQueryVo.getHdId()); hdQueryVoSingle.setHdType(hdQueryVo.getHdType()); hdQueryVoSingle.setHdTitle(hdQueryVo.getHdTitle()); hdQueryVoSingle.setHdStartDate(hdQueryVo.getHdStartDate()); hdQueryVoSingle.setHdEndDate(hdQueryVo.getHdEndDate()); hdQueryVoSingle.setHdStatus(hdQueryVo.getHdStatus()); hdQueryVoSingle.setHdImage(hdQueryVo.getHdImage()); hdQueryVoSingle.setHdNumber(hdQueryVo.getHdNumber()); hdQueryVoSingle.setGmtCreate(hdQueryVo.getGmtCreate()); hdQueryVoSingle.setGmtModified(hdQueryVo.getGmtModified()); hdQueryVoSingle.setUserId(hdQueryVo.getUserId()); if (hdQueryVo.getHdType().equals(0)) { hdQueryVoSingle.setHdJoinUsers(onlineWorksMapper.getOnlineJoinUsers(hdQueryVo.getHdId())); } else { hdQueryVoSingle.setHdJoinUsers(offlineUsersMapper.getOfflineJoinUsers(hdQueryVo.getHdId())); } hdQueryVos.add(hdQueryVoSingle); } PageInfo<HdQueryVo> pageViewInfo = new PageInfo<>(hdQueryVos); return pageViewInfo; }
能够分页,可是数据量错误,total始终等于每页数据量,即pageSizegit
@Override public PageInfo<HdQueryVo> getRecordsByView(int pageNo, int pageSize) { List<HdQueryVo> hdQueryVosByView = actionMapper.getActionByView(); List<HdQueryVo> hdQueryVos = new ArrayList<>(); for (HdQueryVo hdQueryVo : hdQueryVosByView) { HdQueryVo hdQueryVoSingle = new HdQueryVo(); hdQueryVoSingle.setHdId(hdQueryVo.getHdId()); hdQueryVoSingle.setHdType(hdQueryVo.getHdType()); hdQueryVoSingle.setHdTitle(hdQueryVo.getHdTitle()); hdQueryVoSingle.setHdStartDate(hdQueryVo.getHdStartDate()); hdQueryVoSingle.setHdEndDate(hdQueryVo.getHdEndDate()); hdQueryVoSingle.setHdStatus(hdQueryVo.getHdStatus()); hdQueryVoSingle.setHdImage(hdQueryVo.getHdImage()); hdQueryVoSingle.setHdNumber(hdQueryVo.getHdNumber()); hdQueryVoSingle.setGmtCreate(hdQueryVo.getGmtCreate()); hdQueryVoSingle.setGmtModified(hdQueryVo.getGmtModified()); hdQueryVoSingle.setUserId(hdQueryVo.getUserId()); if (hdQueryVo.getHdType().equals(0)) { hdQueryVoSingle.setHdJoinUsers(onlineWorksMapper.getOnlineJoinUsers(hdQueryVo.getHdId())); } else { hdQueryVoSingle.setHdJoinUsers(offlineUsersMapper.getOfflineJoinUsers(hdQueryVo.getHdId())); } hdQueryVos.add(hdQueryVoSingle); } PageHelper.startPage(pageNo,pageSize); PageInfo<HdQueryVo> pageViewInfo = new PageInfo<>(hdQueryVos); return pageViewInfo; }
数据能够查询出来,总数total也正确,可是分页功能失效。(这份阿里 Java 开发手册能够关注公众号Java核心技术,回复:手册)面试
PageHelper中startPage开启分页方法只对后面的sql查询起做用spring
1.1 错误缘由是提早开启分页后,对list操做,即PageInfo pageViewInfo = new PageInfo<>(hdQueryVos);
sql
/** * 包装Page对象 * * @param list */ public PageInfo(List list) { this(list, 8); }
只是把list转为PageInfo对象,不影响前面分页数据的操做api
1.2 错误缘由是先对list操做后,开启翻页后没有sql语句intellij-idea
即sql语句没有参与分页查询app
直接对分页后的PageInfo对象中的数据进行操做ide
@Override public PageInfo<HdQueryVo> getRecordsByView(int pageNo, int pageSize) { PageInfo<HdQueryVo> source = PageHelper.startPage(pageNo, pageSize).doSelectPageInfo(()->{ actionMapper.getActionByView(); }); // 须要转换的对象 PageInfo<HdQueryVo> target = new PageInfo<>(); // 复制分页属性 BeanUtils.copyProperties(source, target); // 对查询的list进行下一步操做,好比类型转换后 List<HdQueryVo> collect = source.getList().stream().collect(Collectors.toList()); List<HdQueryVo> hdQueryVos = new ArrayList<>(); for (HdQueryVo hdQueryVo : collect) { HdQueryVo hdQueryVoSingle = new HdQueryVo(); hdQueryVoSingle.setHdId(hdQueryVo.getHdId()); hdQueryVoSingle.setHdType(hdQueryVo.getHdType()); hdQueryVoSingle.setHdTitle(hdQueryVo.getHdTitle()); hdQueryVoSingle.setHdStartDate(hdQueryVo.getHdStartDate()); hdQueryVoSingle.setHdEndDate(hdQueryVo.getHdEndDate()); hdQueryVoSingle.setHdStatus(hdQueryVo.getHdStatus()); hdQueryVoSingle.setHdImage(hdQueryVo.getHdImage()); hdQueryVoSingle.setHdNumber(hdQueryVo.getHdNumber()); hdQueryVoSingle.setGmtCreate(hdQueryVo.getGmtCreate()); hdQueryVoSingle.setGmtModified(hdQueryVo.getGmtModified()); hdQueryVoSingle.setUserId(hdQueryVo.getUserId()); if (hdQueryVo.getHdType().equals(0)) { hdQueryVoSingle.setHdJoinUsers(onlineWorksMapper.getOnlineJoinUsers(hdQueryVo.getHdId())); } else { hdQueryVoSingle.setHdJoinUsers(offlineUsersMapper.getOfflineJoinUsers(hdQueryVo.getHdId())); } hdQueryVos.add(hdQueryVoSingle); } // 加工后的数据放入新的pageinfo target.setList(hdQueryVos); return target; }
参考资料:工具
https://apidoc.gitee.com/free...
https://blog.csdn.net/shangle...
原文连接:https://blog.csdn.net/qq_3508...
版权声明:本文为CSDN博主「He Ain't Hero」的原创文章,遵循CC 4.0 BY-SA版权协议,转载请附上原文出处连接及本声明。
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