【SpringBoot】分页查询和映射配置文件写动态SQL

接口文档

pojo类

package com.heo.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.util.List;

//分页返回结果对象
@Data
@NoArgsConstructor
@AllArgsConstructor
public class PageBean <T>{
    private Long total;//总条数
    private List<T> items;//当前页数据集合
}

controller

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

service

    @Override
    public PageBean<Article> list(Integer pageNum, Integer pageSize, Integer categoryId, String state) {
        PageBean<Article> pb = new PageBean<>();
        PageHelper.startPage(pageNum, pageSize);
        Map<String, Object> map = ThreadLocalUtil.get();
        Integer userId = (Integer) map.get("id");
        List<Article> as = articleMapper.list(userId, categoryId, state);
        Page<Article> p = (Page<Article>) as;
        pb.setTotal(p.getTotal());
        pb.setItems(p.getResult());
        return pb;
    }

pagehelper 依赖

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

mapper

List<Article> list(Integer userId, Integer categoryId, String state);

映射配置文件写动态SQL

映射配置文件与源目录结构一致，创建 com/heo/mapper（这里是 / 分隔）。文件名字也需要一致。

<?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.heo.mapper.ArticleMapper">
    <!--动态 sql-->
    <select id="list" resultType="com.heo.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>