Mybatis和MybatisPlus使用分页插件

Mybatis分页

• 安装Pagehelper插件

    <dependency>
        <groupId>com.github.pagehelpergroupId>
        <artifactId>pagehelper-spring-boot-starterartifactId>
        <version>1.4.2version>
    dependency>

• 分页查询

   public PageBean selectByPage(String name, Integer gender, LocalDate begin, LocalDate end, Integer page, Integer pageSize) {
    PageHelper.startPage(page, pageSize);
    // 执行分页查询
    List<Emp> empList = empMapper.selectEmps(name,gender,begin,end);
    // 获取分页结果
    Page<Emp> p = (Page<Emp>) empList;
    //封装PageBean
    PageBean pageBean = new PageBean(p.getTotal(), p.getResult());
    return pageBean;
}

MybatisPlus分页

• 设置配置类

@Configuration
public class MybatisConfig {
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor(){
        //初始化核心插件
        MybatisPlusInterceptor interceptor=new MybatisPlusInterceptor();
        //添加分页插件
        PaginationInnerInterceptor paginationInnerInterceptor=new PaginationInnerInterceptor(DbType.MYSQL);
        //设置分页上线
        paginationInnerInterceptor.setMaxLimit(1000L);
        //添加插件
        interceptor.addInnerInterceptor(paginationInnerInterceptor);
        return interceptor;
    }
}

• 分页查询

    @Override
    public void page(EmployeePageQueryDTO employeePageQueryDTO){
    	//初始化
        Page<Employee> page=new Page<>(employeePageQueryDTO.getPage(),employeePageQueryDTO.getPageSize());
        //设置where
        LambdaQueryWrapper<Employee> lambdaQueryWrapper=new LambdaQueryWrapper<>();
        lambdaQueryWrapper.like(StringUtils.hasLength(employeePageQueryDTO.getName()),
                Employee::getName,employeePageQueryDTO.getName());
        lambdaQueryWrapper.orderByDesc(Employee::getUpdateTime);
        lambdaQueryWrapper.orderByAsc(Employee::getCreateTime);
        //查询
        employeeMapper.selectPage(page,lambdaQueryWrapper);
        System.out.println(page.getTotal());
        System.out.println(page.getRecords());
    }

• MybatisPlus多表分页查询
  MybatisPlus对单表查询地支持较为丰富，但对多表操作的支持比较少，建议直接使用Mybatis的方式去实现多表操作。
  1. Service的实现

      @Override
  public PageResult page(DishPageQueryDTO dishPageQueryDTO) {
      Page<DishVO> page=new Page<>(dishPageQueryDTO.getPage(),dishPageQueryDTO.getPageSize());
      //分页查询
      dishMapper.selectDishPage(page,dishPageQueryDTO);
      return new PageResult(page.getTotal(),page.getRecords());
  }
  

  2. Mapper的实现

   Page<DishVO> selectDishPage(Page<DishVO> page, DishPageQueryDTO dishPageQueryDTO);
  

  3. Mapper.xml的实现

  
  <select id="selectDishPage" resultType="com.sky.vo.DishVO">
      select dish.id as id,dish.name as name,dish.price as price,
             dish.image as image,dish.description as description,
             dish.status as status,dish.update_time as updateTime,
             category.name as categoryName
      from dish join  category on dish.category_id=category.id
      <where>
          <if test="dishPageQueryDTO.name!=null">dish.name like concat('%',#{dishPageQueryDTO.name},'%')if>
          <if test="dishPageQueryDTO.categoryId!=null">dish.category_id=#{dishPageQueryDTO.categoryId}if>
          <if test="dishPageQueryDTO.status!=null">status=#{dishPageQueryDTO.status}if>
      where>
  select>