1、IndexTagController.java
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@GetMapping ( "/tags/{id}" ) public String types( @PageableDefault (size = 3 ,sort = { "updateTime" },direction = Sort.Direction.DESC)Pageable pageable, @PathVariable long id, Model model, HttpSession session){ //找到所有的标签,并且按照标签新闻量排序 List<Tag> tags = tagService.listTagTop( 50 ); if (id == - 1 ){ //得到最大数据量的分类 id = tags.get( 0 ).getId(); } model.addAttribute( "tags" ,tags); model.addAttribute( "page" ,newsService.listNews(id,pageable)); model.addAttribute( "activeId" ,id); session.setAttribute( "query" , "" ); return "tags" ; } |
newService.listNews(id,pgeable)中id为标签的id,这个方法要做的就是查询出标签中包含id为参数id的所有新闻。
2、业务层代码
NewService.java是一个接口,其中存在以下方法
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//根据标签Id查找符合条件的新闻 Page<News> listNews( long id,Pageable pageable); |
NewServiceImpl.java为实现NewService接口的类,实现listNews方法
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@Override public Page<News> listNews( long id, Pageable pageable) { return newsRepository.findAll( new Specification() { @Override public Predicate toPredicate(Root root, CriteriaQuery cq, CriteriaBuilder cb) { //外连接查询 Join Join join =root.join( "tags" ); return cb.equal(join.get( "id" ),id); } },pageable); } |
NewsRepository.java 继承了JpaSpecificationExecutor
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public interface NewsRepository extends JpaRepository<News,Long>, JpaSpecificationExecutor { @Query ( "select n from News n where n.recommend = true " ) List<News> findTop(Pageable pageable); @Query ( "select n from News n where n.title like ?1 or n.content like ?1" ) Page<News> findByQuery(String query,Pageable pageable); @Query ( "select function('date_format',n.updateTime,'%Y') as year1 from News n group by year1 order by year1 desc " ) List<String> findGroupYear(); @Query ( "select n from News n where function('date_format',n.updateTime,'%Y') = ?1 " ) List<News> findByYear(String year); } |
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原文链接:https://blog.csdn.net/qq_41708916/article/details/107795979