分页处理

1.自定义分页查询

import java.io.Serializable;

public class PageReq implements Serializable {

    /**
     * 当前页
     */
    private Integer current;

    /**
     * 分页偏移量
     */
    private Integer offSet;

    /**
     * 每页条数
     */
    private Integer pageSize;

    public Integer getOffSet() {
        return ((current == null || current < 1 ? 1 : current) - 1) * (pageSize == null ? 20 : pageSize);
    }

    public Integer getCurrent() {
        if (current == null) {
            current = 1;
        }
        return current;
    }

    public void setCurrent(Integer current) {
        this.current = current;
    }

    public Integer getPageSize() {
        if (pageSize == null) {
            pageSize = 20;
        }
        return pageSize;
    }

    public void setPageSize(Integer pageSize) {
        this.pageSize = pageSize;
    }
}

xml里使用方式

<select id="pageSchoolsAndUser" resultType="mode.vo.SchoolInfoVO">
    SELECT t1.school_id           schoolId,
    t1.school_name         schoolName,
    t2.USH014              schoolHeader,
    t1.signed_grade_number signedGradeNumber,
    t1.signed_class_number signedClassNumber,
    t1.status
    FROM tb_school_info t1
    LEFT JOIN szush t2 ON t1.headmaster_id = t2.USH001
    LIMIT #{offSet}, #{pageSize}
</select>

2.针对自动分页处理任务场景

@Test
public void selectBatch() {
    // 查询总条数
    int totalCount = 10000;
    // 每次查询条数
    int queryBatchCount = 1000;
    // 已经查询的条数
    int passCount = 0;
    do {
        System.out.println("select * from a limit " + passCount + "," + queryBatchCount);
        passCount = queryBatchCount + passCount;
    } while (passCount <= totalCount);
}