Spring Boot----PageHelper

不使用PageHelper

　　需要进行两次查询，一次查询总数，用来计算前端分页的页码数量，一次查询数据；

public PageResult query(IplogQueryObject qo) {
		int totalCount = this.iplogMapper.queryForCount(qo);
		if (totalCount > 0) {
			List<Iplog> list = this.iplogMapper.query(qo);
			PageResult pageResult = new PageResult(list, totalCount, qo.getCurrentPage(),
					qo.getPageSize());
			return pageResult;
		}
		return PageResult.empty(qo.getPageSize());
	}

　　在dao需要写limit

<select id="query" resultMap="BaseResultMap">
    SELECT <include refid="base_column" />
    FROM iplog
    <include refid="base_where" />
    ORDER BY loginTime DESC
    LIMIT #{start},#{pageSize}
  </select>

　　

使用PageHelper

依赖

<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper‐spring‐boot‐starter</artifactId>         
    <version>1.2.4</version>
</dependency>

 

在application.yml中配置pageHelper操作的数据库类型

PageHelper测试

　　注意:PageHelper只对第一个查询有效

　　定义接口

@Mapper
public interface CourseMapper {
    Page<CourseInfo> findCourseListPage(CourseListRequest courseListRequest)
};

　　定义mapper.xml映射文件（不需要加limit）

<select id="findCourseListPage" resultType="com.xuecheng.framework.domain.course.ext.CourseInfo" parameterType="com.xuecheng.framework.domain.course.request.CourseListRequest">
　　SELECT * FROM course_base
</select>

　　测试

    //测试分页
    @Test
    public void testPageHelper() {
        PageHelper.startPage(1, 10);//查询第一页，每页显示10条记录
        CourseListRequest courseListRequest = new CourseListRequest();
        Page<CourseInfo> courseListPage = courseMapper.findCourseListPage(courseListRequest);
        List<CourseInfo> result = courseListPage.getResult();
　　　　  Long l = courseListPage.getTotal();
        System.out.println(courseListPage);
    }

　　使用二

        PageHelper.startPage(pageNumber, pageSize);
        classCountStatistics = schoolClassMapper.getMajorCountStatistics(startYear, schoolTerm, classYear, null, schoolId, 0, id);
        PageInfo<ClassStuSelectionCountInfoVo> classStuSelectionCountInfoVoPageInfo = new PageInfo<>(classCountStatistics);