Mybatis 分页插件 PageHelper

使用步骤：(不咋好用)

1.导入依赖：

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
    <version>1.3.0</version>
</dependency>

2.修改配置文件 application.properties；加入以下配置：

pagehelper.reasonable=true
pagehelper.page-size-zero=true

3.开启IDEA控制台日志：

# 打印 SQL 日志
logging.level.cn.js.mapper=trace  #-------->对mapper层开启日志
logging.level.root=info  #-------->日志等级

4.定义一个公共接收分页参数的公共类：

// 封装分页查询参数的
@Setter
@Getter
public class QueryObject {
    private int currentPage = 1; // 封装查询第几页
    private int pageSize = 5; // 封装查询每页多少条
}

5.编写Controller层：

@RestController
@RequestMapping("/test")
public class PageTestController {
    @Autowired
    private DepartmentService departmentService;
    @PostMapping("/page")

    public PageInfo<Department> pageI(@RequestBody QueryObject qo){
        PageInfo<Department> pageInfo=departmentService.queryt(qo);
        return pageInfo;
    }
}

6.编写Service 层：

   public interface DepartmentService {
   //分页测试
    PageInfo<Department> queryt(QueryObject qo);
   
   }

7.编写ServiceImpl 实现层：

@Service  
@Slf4j  //打上日志注解开启日志
public class DepartmentServiceImpl implements DepartmentService {
	 @Autowired
     private DepartmentMapper departmentMapper;
	 //分页测试
    @Override
    public PageInfo<Department> queryt(QueryObject qo) {
        // 使用分页插件传入当前页，每页显示数量。告诉PageHelper。
        PageHelper.startPage(qo.getCurrentPage(),qo.getPageSize());
        List<Department> seleall = departmentMapper.seleall(qo); //查询数据
        PageInfo<Department> paget = new PageInfo<>(seleall);
        return paget;
    }
}

8.编写Mapper 层：

public interface DepartmentMapper {
  
    List<Department> seleall(QueryObject qo);
}

9.编写Mapper.XmL 文件：

<?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="cn.js.mapper.DepartmentMapper">

    <select id="seleall" resultType="cn.js.domain.Department">
        select * from department
    </select>
</mapper>

10.测试：

日志：