PageHelper 笔记

一、Maven依赖

    com.github.pagehelper
    pagehelper
    5.1.8

二、分页查询

1、List列表
@Test
    public void findPage(){
        PageHelper.startPage(1, 2, true);
        List list = productCategoryMapper.selectAll();
       log.info(JSON.toJSONString(list));
    }
返回数据：
[{"categoryImg":"https://ss0.baidu.com/6ONWsjip0QIZ8tyhnq/it/u=2634938388,2218013244&fm=173&app=49&f=JPEG?w=640&h=368&s=1FB4C4041E28230F7C1448840300D0AE","categoryName":"商口","categorySort":0,"id":"1073149717596823552","parentId":"0","status":1,"updateTime":1544694082000},{"categoryImg":"https://ss0.baidu.com/6ONWsjip0QIZ8tyhnq/it/u=2634938388,2218013244&fm=173&app=49&f=JPEG?w=640&h=368&s=1FB4C4041E28230F7C1448840300D0AE","categoryName":"商口1","categorySort":0,"createTime":1544695821000,"id":"1073158172968820736","parentId":"0","status":1}]
2、带分页参数
1)分页类
@Data
public class PageBean implements Serializable {
    private static final long serialVersionUID = 8656597559014685635L;
    private long total;        //总记录数
    private List list;    //结果集
    private int pageNum;    // 第几页
    private int pageSize;    // 每页记录数
    private int pages;        // 总页数
    private int size;        // 当前页的数量 <= pageSize，该属性来自ArrayList的size属性

    /**
     * @param list
     */
    public PageBean(List list) {
        if (list instanceof Page) {
            Page page = (Page) list;
            this.pageNum = page.getPageNum();
            this.pageSize = page.getPageSize();
            this.total = page.getTotal();
            this.pages = page.getPages();
            this.list = page;
            this.size = page.size();
        }
    }
}
2)测试
    @Test
    public void findPage(){
        PageHelper.startPage(1, 2, true);
        List list = productCategoryMapper.selectAll();
        PageBean pageBean=new PageBean(list);
        log.info(JSON.toJSONString(pageBean));
    }
返回数据：
{"list":[{"categoryImg":"https://ss0.baidu.com/6ONWsjip0QIZ8tyhnq/it/u=2634938388,2218013244&fm=173&app=49&f=JPEG?w=640&h=368&s=1FB4C4041E28230F7C1448840300D0AE","categoryName":"商口","categorySort":0,"id":"1073149717596823552","parentId":"0","status":1,"updateTime":1544694082000},{"categoryImg":"https://ss0.baidu.com/6ONWsjip0QIZ8tyhnq/it/u=2634938388,2218013244&fm=173&app=49&f=JPEG?w=640&h=368&s=1FB4C4041E28230F7C1448840300D0AE","categoryName":"商口1","categorySort":0,"createTime":1544695821000,"id":"1073158172968820736","parentId":"0","status":1}],"pageNum":1,"pageSize":2,"pages":2,"size":2,"total":3}