springboot——新闻列表主页显示和新闻详情页

本次实现了新闻的主页显示、新闻搜索和新闻详情页。

• 实现新闻列表的展示
• 左侧展示分类、标签和推荐新闻
• 实现全局搜索，可以搜索标题或文章内容
• 点击新闻可以进入新闻详情页，并支持Md

1. 在

   NewsRepository

   、

   TagRespository

   和

   TypeRespository

   接口中添加需要进行的数据库操作方法

   //查询推荐新闻
   @Query("select n from News n where n.recommend = true ")
   List<News> findTop(Pageable pageable);
   
   //进行全局搜索的数据库操作
   @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 t from Tag t")
   List<Tag> findTop(Pageable pageable);

   @Query("select t from Type t")
   List<Type> findTop(Pageable pageable);

2. 设计

   util.MarkdownUtils

   类，对md格式新闻进行支持

   public class MarkdownUtils {
   
   /**
   * markdown格式转换成HTML格式
   * @param markdown
   * @return
   */
   public static String markdownToHtml(String markdown) {
   Parser parser = Parser.builder().build();
   Node document = parser.parse(markdown);
   HtmlRenderer renderer = HtmlRenderer.builder().build();
   return renderer.render(document);
   }
   
   /**
   * 增加扩展[标题锚点，表格生成]
   * Markdown转换成HTML
   * @param markdown
   * @return
   */
   public static String markdownToHtmlExtensions(String markdown) {
   //h标题生成id
   Set<Extension> headingAnchorExtensions = Collections.singleton(HeadingAnchorExtension.create());
   //转换table的HTML
   List<Extension> tableExtension = Arrays.asList(TablesExtension.create());
   Parser parser = Parser.builder()
   .extensions(tableExtension)
   .build();
   Node document = parser.parse(markdown);
   HtmlRenderer renderer = HtmlRenderer.builder()
   .extensions(headingAnchorExtensions)
   .extensions(tableExtension)
   .attributeProviderFactory(new AttributeProviderFactory() {
   public AttributeProvider create(AttributeProviderContext context) {
   return new CustomAttributeProvider();
   }
   })
   .build();
   return renderer.render(document);
   }
   
   /**
   * 处理标签的属性
   */
   static class CustomAttributeProvider implements AttributeProvider {
   @Override
   public void setAttributes(Node node, String tagName, Map<String, String> attributes) {
   //改变a标签的target属性为_blank
   if (node instanceof Link) {
   attributes.put("target", "_blank");
   }
   if (node instanceof TableBlock) {
   attributes.put("class", "ui celled table");
   }
   }
   }
   
   public static void main(String[] args) {
   String table = "| hello | hi   | 哈哈哈   |\n" +
   "| ----- | ---- | ----- |\n" +
   "| 斯维尔多  | 士大夫  | f啊    |\n" +
   "| 阿什顿发  | 非固定杆 | 撒阿什顿发 |\n" +
   "\n";
   String a = "[imCoding 爱编程](http://www.lirenmi.cn)";
   System.out.println(markdownToHtmlExtensions(a));
   }
   
   }

3. 在相应的

   xxxServiceImpl

   中实现全局搜索、markdown语法支持、展示新闻详情页、新闻主页、左侧类型、标签和推荐新闻的方法

   //返回新闻列表
   @Override
   public Page<News> listNews(Pageable pageable) {
   return newsRepository.findAll(pageable);
   }
   
   //进行全局搜索
   @Override
   public Page<News> listNews(String query, Pageable pageable) {
   return newsRepository.findByQuery(query, pageable);
   }
   
   //返回推荐新闻列表
   @Override
   public List<News> listRecommendNewsTop(Integer size) {
   Sort sort = Sort.by(Sort.Direction.DESC, "updateTime");
   Pageable pageable = PageRequest.of(0, size, sort);
   return newsRepository.findTop(pageable);
   }
   
   //转换md格式新闻
   @Override
   public News getAndConvert(Long id) {
   News news = newsRepository.findById(id).orElse(null);
   if (news == null) {
   System.out.println("该新闻不存在");
   }
   News news1 = new News();
   BeanUtils.copyProperties(news, news1);
   String content = news1.getContent();
   news1.setContent(MarkdownUtils.markdownToHtmlExtensions(content));
   return news1;
   }

   //返回类型列表
   @Override
   public List<Tag> listTagTop(Integer size) {
   Sort sort = Sort.by(Sort.Direction.DESC, "newsList.size");
   Pageable pageable = PageRequest.of(0, size, sort);
   return tagRepository.findTop(pageable);
   }

   //返回标签列表
   @Override
   public List<Type> listTypeTop(Integer size) {
   Sort sort = Sort.by(Sort.Direction.DESC, "news.size");
   Pageable pageable = PageRequest.of(0, size, sort);
   return typeRepository.findTop(pageable);
   }

4. 设计

   web.IndexController

   类，相应web页面的请求，进行新闻主页的展示、搜索和点击进入详情页

   @Controller
   public class IndexController {
   
   @Autowired
   private TypeService typeService;
   
   @Autowired
   private TagService tagService;
   
   @Autowired
   private NewsService newsService;
   
   @GetMapping("/")
   public String index(@PageableDefault(size = 3, sort = {"updateTime"}, direction = Sort.Direction.DESC) Pageable pageable, Model model) {
   model.addAttribute("page", newsService.listNews(pageable));
   model.addAttribute("types", typeService.listTypeTop(3));
   model.addAttribute("tags", tagService.listTagTop(3));
   model.addAttribute("recommendNews", newsService.listRecommendNewsTop(3));
   return "index";
   }
   
   @PostMapping("/search")
   public String search(@PageableDefault(size = 3, sort = {"updateTime"}, direction = Sort.Direction.DESC) Pageable pageable,
   @RequestParam String query, Model model) {
   model.addAttribute("page", newsService.listNews("%"+query+"%", pageable));
   model.addAttribute("query", query);
   return "search";
   }
   
   @RequestMapping("/news/{id}")
   public String news(@PathVariable Long id, Model model) {
   model.addAttribute("news", newsService.getAndConvert(id));
   return "new";
   }
   
   }

5. 项目运行测试