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