上海网站开发建设价格,广西住房城乡和建设厅网站,抖音视频添加小程序怎么赚钱,做网站找哪个公司好pagehelper分页查询
PageHelper是MyBatis框架中提供的分页插件#xff0c;它支持Oracle、Mysql、MariaDB、SQLite、Hsqldb、PostgreSQL六种数据库。使用PageHelper可以方便地进行分页查询#xff0c;只需在SQL查询前调用PageHelper.startPage方法并传入两个参数#xff1a;…pagehelper分页查询
PageHelper是MyBatis框架中提供的分页插件它支持Oracle、Mysql、MariaDB、SQLite、Hsqldb、PostgreSQL六种数据库。使用PageHelper可以方便地进行分页查询只需在SQL查询前调用PageHelper.startPage方法并传入两个参数page页码rows每页显示的条数。例如PageHelper.startPage(1, 20)表示请求第一页每页显示20条数据。
1.pom文件
引入 pagehelper pom文件 dependencygroupIdcom.github.pagehelper/groupIdartifactIdpagehelper-spring-boot-starter/artifactId/dependency2.Controller
控制层接收到/page请求传递到后台参数封装为了EmployeePageQueryDTO对象
调用service层 /*** 员工分页查询* param employeePageQueryDTO* return*/GetMapping(/page)ApiOperation(员工分页查询)public ResultPageResult page(EmployeePageQueryDTO employeePageQueryDTO) {log.info(员工分页查询,参数为: {}, employeePageQueryDTO);PageResult pageResult employeeService.pageQuery(employeePageQueryDTO);return Result.success(pageResult);} 2.PageResult
封装的分页查询结果
/*** 封装分页查询结果*/
Data
AllArgsConstructor
NoArgsConstructor
public class PageResult implements Serializable {private long total; //总记录数private List records; //当前页数据集合
}3.EmployeePageQueryDTO
封装的前台传递过来的数据
Data
public class EmployeePageQueryDTO implements Serializable {//员工姓名private String name;//页码private int page;//每页显示记录数private int pageSize;
}4.Service /*** 分页查询* param employeePageQueryDTO* return*/PageResult pageQuery(EmployeePageQueryDTO employeePageQueryDTO);5.ServiceImpl
调用PageHelper方法进行分页查询
需要两个参数 页码和每一页展示的数量个数 /*** 分页查询* param employeePageQueryDTO* return*/public PageResult pageQuery(EmployeePageQueryDTO employeePageQueryDTO) {//开始分页查询PageHelper.startPage(employeePageQueryDTO.getPage(), employeePageQueryDTO.getPageSize());PageEmployee page employeeMapper.pageQuery(employeePageQueryDTO);long total page.getTotal();ListEmployee result page.getResult();return new PageResult(total, result);}6.Employee
员工的实体类
Data
Builder
NoArgsConstructor
AllArgsConstructor
public class Employee implements Serializable {private static final long serialVersionUID 1L;private Long id;private String username;private String name;private String password;private String phone;private String sex;private String idNumber;private Integer status;//JsonFormat(pattern yyyy-MM-dd HH:mm:ss)private LocalDateTime createTime;//JsonFormat(pattern yyyy-MM-dd HH:mm:ss)private LocalDateTime updateTime;private Long createUser;private Long updateUser;
}7.mapper /*** 分页查询* param employeePageQueryDTO* return*/PageEmployee pageQuery(EmployeePageQueryDTO employeePageQueryDTO);8.mapper.xml
PageHelper会自动的补全sql代码
select idpageQuery resultTypecom.sky.entity.Employeeselect * from employeewhereif testname ! null and name ! and name like concat(%,#{name},%)/if/whereorder by create_time desc/select控制台输出记录2023-10-10 22:37:55.033 INFO 18988 --- [nio-8080-exec-5] c.s.controller.admin.EmployeeController : 员工分页查询,参数为: EmployeePageQueryDTO(namenull, page1, pageSize10)
2023-10-10 22:37:55.239 DEBUG 18988 --- [nio-8080-exec-5] c.s.m.EmployeeMapper.pageQuery_COUNT : Preparing: SELECT count(0) FROM employee
2023-10-10 22:37:55.240 DEBUG 18988 --- [nio-8080-exec-5] c.s.m.EmployeeMapper.pageQuery_COUNT : Parameters:
2023-10-10 22:37:55.246 DEBUG 18988 --- [nio-8080-exec-5] c.s.m.EmployeeMapper.pageQuery_COUNT : Total: 12023-10-10 22:37:55.250 DEBUG 18988 --- [nio-8080-exec-5] com.sky.mapper.EmployeeMapper.pageQuery : Preparing: select * from employee order by create_time desc LIMIT ?//这里显示了 自动补全的代码LIMIT2023-10-10 22:37:55.252 DEBUG 18988 --- [nio-8080-exec-5] com.sky.mapper.EmployeeMapper.pageQuery : Parameters: 10(Integer)
2023-10-10 22:37:55.256 DEBUG 18988 --- [nio-8080-exec-5] com.sky.mapper.EmployeeMapper.pageQuery : Total: 4
