sprinboot实现分页查询

1.环境介绍：

springboot2.7.4

pagehelper1.4.6

mybatis-plus3.5.1

2.需求分析

　　通过前端传回的分页要求的参数<页码，页数据量>，返回结果

　　实现

{
    "code": 0,
    "message": "操作成功",
    "data": {
        "total": 5,
        "items": [
            {
                "id": 1,
                "title": "背景2",
                "content": "测试,测试2,测试3,测试4......",
                "coverImg": "https://www.bing.com",
                "state": "已发布",
                "categoryId": 2,
                "createUser": 3,
                "createTime": "2024-02-01T14:43:27",
                "updateTime": "2024-02-01T14:43:27"
            },
            {
                。。。}

3.具体实现步骤

1. 构建controller类，接受参数

   public Result<PageBean<Article>> list(
               Integer pageNum,Integer pageSize,
               @RequestParam(required = false) Integer categoryId,
               @RequestParam(required = false) String state
       )

   可通过@RequestParam指定该参数是否必须

2. impl中实现

   @Override
       public PageBean<Article> list(Integer pageNum, Integer pageSize, Integer categoryId, String state) {
           PageBean<Article> pb = new PageBean<>();//PageBean包含一个total，和一个泛型List
           PageHelper.startPage(pageNum,pageSize);//使用PageHelper实现分页
           Map<String,Object> map = ThreadLocalUtil.get();
           Integer userId = (Integer) map.get("id");//查询用户创建的文章时，从threadLocal中读取用户id
           List<Article> as = articleMapper.list(userId,categoryId,state);
           Page<Article> p = (Page<Article>)as;//将List强制转换为Page子类，以调用Page子类中方法
           pb.setTotal(p.getTotal());
           pb.setItems(p.getResult());
           return pb;
       }
   

3. mapper.xml实现

   <select id="list" resultType="com.example.springdemo.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>

    

存在问题：idea在xml中没有代码提示实体类的全路径，影响编码体验