SpringBoot（十二）文章列表查询

SpringBoot（十二）

文章列表查询

分页pagehelper依赖

<dependency>
  <groupId>com.github.pagehelper</groupId>
  <artifactId>pagehelper-spring-boot-starter</artifactId>
  <version>1.4.6</version>
</dependency>

1、Controller层

@RestController
@RequestMapping("/article")
public class ArticleController {

    @Autowired
    private ArticleService articleService;

    @PostMapping
    public Result add(@RequestBody @Validated Article article){
        articleService.add(article);
        return Result.success();
    }

    @GetMapping
    public Result<PageBean<Article>> list(
            Integer pageNum,
            Integer pageSize,
            @RequestParam(required = false) String categoryId,//注意非必选参数
            @RequestParam(required = false) String state){
        PageBean<Article> pb = articleService.list(pageNum,pageSize,categoryId,state);
        return Result.success(pb);
    }
}

2、PageBean

@Data
@NoArgsConstructor
@AllArgsConstructor
public class PageBean<T> {

    private Long total;
    private List<T> items;
}

3、service层

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

    @Override
    public void add(Article article) {

        article.setCreateTime(LocalDateTime.now());
        article.setUpdateTime(LocalDateTime.now());

        Map<String,Object> map = ThreadLocalUtil.get();
        Integer o = (Integer) map.get("id");
        article.setCreateUser(o);


        articleMapper.add(article);
    }

    @Override
    public PageBean<Article> list(Integer pageNum, Integer pageSize, String categoryId, String state) {
        //创建PageBean对象
        PageBean<Article> pb = new PageBean<>();
        //开启分页查询  pageHelper
        PageHelper.startPage(pageNum,pageSize);
        //调用mapper
        Map<String,Object> map = ThreadLocalUtil.get();
        Integer userId = (Integer) map.get("id");
        List<Article> as = articleMapper.list(userId,categoryId,state);

        //Page中提供了方法 可以获得PageHelper分页查询后 得到的总记录条数和当前页数据
        Page<Article> p = (Page<Article>) as;
        //把数据填充到PageBean对象中
        pb.setTotal(p.getTotal());
        pb.setItems(p.getResult());
        return pb;
    }
}

4、mapper层

@Mapper
public interface ArticleMapper {

    @Insert("insert into article(title,content,cover_img,state,category_id,create_user,create_time,update_time) " +
            "values (#{title},#{content},#{coverImg},#{state},#{categoryId},#{createUser},#{createTime},#{updateTime})")
    void add(Article article);

    //动态sql 使用注解写太麻烦 需要用映射配置文件
    List<Article> list(Integer userId, String categoryId, String state);
}

5、动态sql 映射配置文件 注意路径与Bean类相同 但是用 / 分割 如com/itheima/mapper

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.itheima.mapper.ArticleMapper"><!--name与mapper相同-->
    <select id="list" resultType="com.itheima.pojo.Article">
        select * from article
        <where>
            <if test="categoryId!=null">
                category_id=#{categoryId}
            </if>

            <if test="state!=null">
               and state=#{state}
            </if>

            and create_user=#{userId}
        </where>
    </select>
    
</mapper>