在Java中如何实现博客文章分类与标签功能_博客分类标签开发指南

-- 文章表
CREATE TABLE article (
  id BIGINT PRIMARY KEY AUTO_INCREMENT,
  title VARCHAR(200) NOT NULL,
  content TEXT,
  category_id BIGINT,
  create_time DATETIME DEFAULT CURRENT_TIMESTAMP,
  FOREIGN KEY (category_id) REFERENCES category(id)
);
<p>-- 分类表
CREATE TABLE category (
id BIGINT PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(50) UNIQUE NOT NULL
);</p><p>-- 标签表
CREATE TABLE tag (
id BIGINT PRIMARY KEY AUTO_INCREMENT,
name VARCHAR(50) UNIQUE NOT NULL
);</p><p>-- 文章-标签关联表（多对多）
CREATE TABLE article_tag (
article_id BIGINT,
tag_id BIGINT,
PRIMARY KEY (article_id, tag_id),
FOREIGN KEY (article_id) REFERENCES article(id) ON DELETE CASCADE,
FOREIGN KEY (tag_id) REFERENCES tag(id) ON DELETE CASCADE
);</p>

@Entity
public class Article {
    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String title;
    private String content;
<pre class='brush:java;toolbar:false;'>@ManyToOne
@JoinColumn(name = "category_id")
private Category category;

@ManyToMany
@JoinTable(
    name = "article_tag",
    joinColumns = @JoinColumn(name = "article_id"),
    inverseJoinColumns = @JoinColumn(name = "tag_id")
)
private Set<Tag> tags = new HashSet<>();

// getter 和 setter

@Service
public class ArticleService {
<pre class='brush:java;toolbar:false;'>@Autowired
private ArticleRepository articleRepo;

@Autowired
private CategoryRepository categoryRepo;

@Autowired
private TagRepository tagRepo;

public Article saveArticle(ArticleDTO dto) {
    Article article = new Article();
    article.setTitle(dto.getTitle());
    article.setContent(dto.getContent());

    // 设置分类
    Category category = categoryRepo.findById(dto.getCategoryId())
        .orElseThrow(() -> new RuntimeException("分类不存在"));
    article.setCategory(category);

    // 处理标签
    Set<Tag> tags = new HashSet<>();
    for (String tagName : dto.getTagNames()) {
        Tag tag = tagRepo.findByName(tagName)
            .orElseGet(() -> {
                Tag newTag = new Tag();
                newTag.setName(tagName);
                return tagRepo.save(newTag);
            });
        tags.add(tag);
    }
    article.setTags(tags);

    return articleRepo.save(article);
}

// 查询某分类下的所有文章
public List<Article> getArticlesByCategory(Long categoryId) {
    return articleRepo.findByCategoryId(categoryId);
}

// 查询某标签下的所有文章
public List<Article> getArticlesByTag(String tagName) {
    return articleRepo.findByTagsName(tagName);
}

public interface ArticleRepository extends JpaRepository<Article, Long> {
    List<Article> findByCategoryId(Long categoryId);
    List<Article> findByTagsName(String tagName);
}

@RestController
@RequestMapping("/api/articles")
public class ArticleController {
<pre class='brush:java;toolbar:false;'>@Autowired
private ArticleService articleService;

@PostMapping
public ResponseEntity<Article> create(@RequestBody ArticleDTO dto) {
    Article saved = articleService.saveArticle(dto);
    return ResponseEntity.ok(saved);
}

@GetMapping("/category/{cid}")
public ResponseEntity<List<Article>> getByCategory(@PathVariable Long cid) {
    return ResponseEntity.ok(articleService.getArticlesByCategory(cid));
}

@GetMapping("/tag/{tagName}")
public ResponseEntity<List<Article>> getByTag(@PathVariable String tagName) {
    return ResponseEntity.ok(articleService.getArticlesByTag(tagName));
}

public class ArticleDTO {
    private String title;
    private String content;
    private Long categoryId;
    private List<String> tagNames;
    // getter 和 setter
}