=============
后端_文章列表
=============

1 用户服务

1.1 用户服务接口

/ysdblog-api/src/main/java/com/weihome/ysdblog/service/UserService.java：

public interface UserService {
    /**
     * 根据用户ID查询用户
     */
     public User findUserById(Long id);
}

1.2 用户服务实现

SQL> select * from t_user where id = 1

/ysdblog-api/src/main/java/com/weihome/ysdblog/service/impl/UserServiceImpl.java：

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;

    @Override
    public User findUserById(Long id) {
        return userMapper.selectById(id);
    }
}

2 标签数据访问

2.1 标签数据访问接口

/ysdblog-api/src/main/java/com/weihome/ysdblog/dao/mapper/TagMapper.java：

public interface TagMapper extends BaseMapper<Tag> {
    /**
     * 根据文章ID查询标签列表
     */
    public List<Tag> findTagsByArticleId(Long articleId);
}

2.2 标签数据访问实现

SQL> select id, tag_name from t_tag where id in (select tag_id from t_article_tag where article_id = 1)

/ysdblog-api/src/main/resources/com/weihome/ysdblog/dao/mapper/TagMapper.xml：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.weihome.ysdblog.dao.mapper.TagMapper">
    <!-- List<Tag> findTagsByArticleId(Long articleId) -->
    <select id="findTagsByArticleId" parameterType="long"
            resultType="com.weihome.ysdblog.dao.pojo.Tag">
        select id, tag_name as tagName from t_tag
        <where>
            id in (select tag_id from t_article_tag
            where article_id = #{articleId})
        </where>
    </select>
</mapper>

3 标签服务

3.1 标签服务接口

/src/main/java/com/weihome/ysdblog/service/TagService.java：

public interface TagService {
    /**
     * 根据文章ID查询标签列表
     */
    public List<TagVo> findTagsByArticleId(Long articleId);
}

3.2 标签服务实现

/src/main/java/com/weihome/ysdblog/service/impl/TagServiceImpl.java：

@Service
public class TagServiceImpl implements TagService {
    @Autowired
    private TagMapper tagMapper;

    @Override
    public List<TagVo> findTagsByArticleId(Long articleId) {
        List<Tag> tags = tagMapper.findTagsByArticleId(articleId);
        return copyList(tags);
    }

    private List<TagVo> copyList(List<Tag> tags) {
        List<TagVo> tagVos = new ArrayList<>();
        for (Tag tag: tags)
            tagVos.add(copy(tag));
        return tagVos;
    }

    private TagVo copy(Tag tag) {
        TagVo tagVo = new TagVo();
        BeanUtils.copyProperties(tag, tagVo);
        return tagVo;
    }
}

4 文章服务

4.1 文章服务接口

/ysdblog-api/src/main/java/com/weihome/ysdblog/service/ArticleService.java：

public interface ArticleService {
    /**
     * 分页查询文章列表
     */
    public Result list(PageParam pageParam);
}

4.2 文章服务实现

SQL> select * from t_article order by weight desc, create_date desc

/ysdblog-api/src/main/java/com/weihome/ysdblog/service/impl/ArticleServiceImpl.java：

@Service
public class ArticleServiceImpl implements ArticleService {
    @Autowired
    private ArticleMapper articleMapper;

    @Autowired
    private UserService userService;

    @Autowired
    private TagService tagService;

    @Override
    public Result list(PageParam pageParam) {
        Page<Article> page = new Page<>(pageParam.getPage(),
            pageParam.getPageSize());
        LambdaQueryWrapper<Article> queryWrapper =
            new LambdaQueryWrapper<>();
        // 按权重降序，权重相同按创建时间降序
        queryWrapper.orderByDesc(
            Article::getWeight, Article::getCreateDate);
        page = articleMapper.selectPage(page, queryWrapper);
        List<Article> articles = page.getRecords();
        return Result.success(copyList(articles, true, true));
    }

    private List<ArticleVo> copyList(
        List<Article> articles, boolean author, boolean tags) {
        List<ArticleVo> articleVos = new ArrayList<>();
        for (Article article: articles)
            articleVos.add(copy(article, author, tags));
        return articleVos;
    }

    private ArticleVo copy(
        Article article, boolean author, boolean tags) {
        ArticleVo articleVo = new ArticleVo();
        BeanUtils.copyProperties(article, articleVo);

        articleVo.setCreateDate(new DateTime(article.getCreateDate())
            .toString("yyyy-MM-dd HH:mm:ss"));

        if (author)
            articleVo.setAuthor(userService.findUserById(
                article.getAuthorId()).getNickname());

        if (tags)
            articleVo.setTags(tagService.findTagsByArticleId(
                article.getId()));

        return articleVo;
    }
}

5 文章控制器

/ysdblog-api/src/main/java/com/weihome/ysdblog/controller/ArticleController.java：

@RestController
@RequestMapping("article")
public class ArticleController {
    @Autowired
    private ArticleService articleService;
    /**
     * 分页查询文章列表
     */
    @PostMapping("list")
    public Result list(@RequestBody PageParam pageParam) {
        return articleService.list(pageParam);
    }
}

6 运行测试

Postman
    POST
        localhost:8888/article/list
    Body
{
    "page": "1",
    "pageSize": "10"
}
------------------------------------------------
{
    "success": true,
    "code": 200,
    "msg": "success",
    "data": [
        {
            "id": "1511577630850203650",
            "commentCount": 0,
            "createDate": "2022-04-06 13:32:45",
            "summary": "summary_b",
            "title": "title_b",
            "viewCount": 0,
            "weight": 0,
            "author": "nickname_a",
            "content": null,
            "category": null,
            "tags": [
                {
                    "id": 1,
                    "tagName": "tag_a"
                },
                {
                    "id": 2,
                    "tagName": "tag_b"
                }
            ]
        },
        {
            "id": "1511577146642972674",
            "commentCount": 0,
            "createDate": "2022-04-06 13:30:50",
            "summary": "summary_a",
            "title": "title_a",
            "viewCount": 1,
            "weight": 0,
            "author": "nickname_a",
            "content": null,
            "category": null,
            "tags": [
                {
                    "id": 1,
                    "tagName": "tag_a"
                },
                {
                    "id": 2,
                    "tagName": "tag_b"
                }
            ]
        }
    ]
}