mybatis-plus分别使用
一、PageHelper插件分页使用
准备1：引入PageHelper依赖
<!-- pagehelper 分页插件 -->
<dependency>
<groupId>com.github.pagehelper</groupId>
<artifactId>pagehelper-spring-boot-starter</artifactId>
<version>1.4.6</version>
</dependency>
准备2：新建表格分页数据对象
import lombok.Data;
import java.io.Serializable;
import java.util.List;
/**
* 表格分页数据对象
*/
@Data
public class TableDataInfo implements Serializable
{
private static final long serialVersionUID = 1L;
/** 总记录数 */
private long total;
/** 列表数据 */
private List<?> rows;
/** 消息状态码 */
private int code;
/** 消息内容 */
private String msg;
}
准备3：分页数据类
import lombok.Data;
/**
* 分页数据
*/
@Data
public class PageDomain
{
/** 当前记录起始索引 */
private Integer pageNum;
/** 每页显示记录数 */
private Integer pageSize;
/** 排序列 */
private String orderByColumn;
/** 排序的方向desc或者asc */
private String isAsc = "asc";
/** 分页参数合理化 */
private Boolean reasonable = true;
public String getOrderBy()
{
if (StringUtils.isEmpty(orderByColumn))
{
return "";
}
return StringUtils.toUnderScoreCase(orderByColumn) + " " + isAsc;
}
public String getIsAsc()
{
return isAsc;
}
public void setIsAsc(String isAsc)
{
if (StringUtils.isNotEmpty(isAsc))
{
// 兼容前端排序类型
if ("ascending".equals(isAsc))
{
isAsc = "asc";
}
else if ("descending".equals(isAsc))
{
isAsc = "desc";
}
this.isAsc = isAsc;
}
}
public Boolean getReasonable()
{
if (StringUtils.isNull(reasonable))
{
return Boolean.TRUE;
}
return reasonable;
}
public void setReasonable(Boolean reasonable)
{
this.reasonable = reasonable;
}
}
准备4：分页工具类
/**
* 分页工具类
*/
public class PageUtils extends PageHelper
{
/**
* 设置请求分页数据
*/
public static void startPage()
{
PageDomain pageDomain = TableSupport.buildPageRequest();
Integer pageNum = pageDomain.getPageNum();
Integer pageSize = pageDomain.getPageSize();
String orderBy = SqlUtil.escapeOrderBySql(pageDomain.getOrderBy());
Boolean reasonable = pageDomain.getReasonable();
PageHelper.startPage(pageNum, pageSize, orderBy).setReasonable(reasonable);
}
}
准备5：响应请求分页数据的方法
/**
* 响应请求分页数据
*/
@SuppressWarnings({ "rawtypes", "unchecked" })
public TableDataInfo getDataTable(List<?> list)
{
TableDataInfo rspData = new TableDataInfo();
rspData.setCode(HttpStatus.SUCCESS);
rspData.setMsg("查询成功");
rspData.setRows(list);
rspData.setTotal(new PageInfo(list).getTotal());
return rspData;
}
正式使用
1、如果只是单表查询，可以用QueryWrapper
controller层
@GetMapping("/list")
public TableDataInfo list(Student s)
{
PageUtils.startPage();
List<Student> list = StudentService.selectStudentList(s);
return getDataTable(list);
}
在service层新增接口以及实现类的方法
List<Student> selectStudentList(Student s);
@Override
public List<Student> selectStudentList(Student s) {
QueryWrapper<Student> queryWrapper = new QueryWrapper<>();
// 所有待查询的条件
if (null != s.getId()) {
queryWrapper.lambda().eq(Student::getId, Student.getId());
}
if (StringUtils.isNotEmpty(s.getStudentName())) {
queryWrapper.lambda().like(Student::getStudentName, s.getStudentName());
}
return kaddOrInfoMapper.selectList(queryWrapper);
}
2、或者自定义SQL要多表查询，可以自己写方法联表查询
controller层
@GetMapping("/list")
public TableDataInfo list(Student s)
{
PageUtils.startPage();
List<Student> list = StudentService.selectStudentList(s);
return getDataTable(list);
}
service层忽略，就去调Mapper层方法就行
Mapper接口
List<Student> selectStudentList(Student s);
Mapper.xml
<select id="selectStudentList" resultType="com.StudentDTO">
SELECT
c.*,
s.*
FROM
classroom c
LEFT JOIN student s ON student.id = classroom.student_id
<where>
<if test="id != null and id != ''">
AND s.id = #{id}
</if>
<if test="studentName != null and studentName != ''">
AND s.bu like concat('%', #{studentName}, '%')
</if>
<!-- <if test="beginTime != null and beginTime != ''"><!– 开始时间检索 –>-->
<!-- and date_format(create_time,'%y%m%d') >= date_format(#{beginTime},'%y%m%d')-->
<!-- </if>-->
<!-- <if test="endTime != null and endTime != ''"><!– 结束时间检索 –>-->
<!-- and date_format(create_time,'%y%m%d') <= date_format(#{endTime},'%y%m%d')-->
<!-- </if>-->
</where>
</select>
二、使用Mybatis-plus自带分页Ipage进行分页
不需要准备，直接正式使用
1、如果只是单表查询，可以用QueryWrapper
controller层
@GetMapping(value = "/listPage")
public IPage findListByPage(StudentQO studentQO) {
return studentService.queryPageList(studentQO);
}
设置查询参数
/**
* 设置查询参数
* @return
*/
private QueryWrapper<Student> getQueryParam(StudentQO studentQO) {
QueryWrapper<KaddPoaOrMatch> queryWrapper = new QueryWrapper<>();
// 所有待查询的条件
if (studentQO.getId() != null) {
queryWrapper.lambda().eq(Student::getId, studentQO.getId());
}
if (studentQO.getStudentName() != null) {
queryWrapper.lambda().like(Student::getStudentName, studentQO.getStudentName());
}
return queryWrapper;
}
service层
@Override
public IPage queryPageList(StudentQO studentQO) {
IPage<StudentQO> page = new Page<>(studentQO.getPageNum(),studentQO.getPageSize());
IPage<StudentQO> iPage = studentMapper.selectPage(page, getQueryParam(studentQO));
return iPage;
}
2、或者自定义SQL要多表查询，可以自己写方法联表查询
controller层一样
@GetMapping(value = "/listPage")
public IPage findListByPage(StudentQO studentQO) {
return studentService.queryPageList(studentQO);
}
service层
@Override
public IPage queryPageList(StudentQO studentQO) {
IPage<StudentQO> page = new Page<>(studentQO.getPageNum(),studentQO.getPageSize());
IPage<StudentQO> iPage = studentMapper.selectStudentList(page, studentQO);
return iPage;
}
Mapper接口
IPage<StudentQO> selectStudentList(@Param("iPage") IPage<StudentQO> iPage, @Param("param") StudentQO studentQO);
Mapper.xml
<select id="selectStudentList" resultType="com.StudentDTO">
SELECT
c.*,
s.*
FROM
classroom c
LEFT JOIN student s ON student.id = classroom.student_id
<where>
<if test="param.id != null and param.id != ''">
AND s.id = #{param.id}
</if>
<if test="param.studentName != null and param.studentName != ''">
AND s.bu like concat('%', #{param.studentName}, '%')
</if>
</where>
</select>
