POJO:

package com.shop.pojo;

import java.io.Serializable;
import java.util.List;

public class PageBean<T> implements Serializable {

    // 分頁中的數(shù)據(jù)
    private List<T> list;
    // 當(dāng)前頁
    private Integer currPage;
    // 每頁條數(shù)
    private Integer pageSize;
    // 總頁數(shù)（不能直接設(shè)置，只能通過計(jì)算得出結(jié)果）
    private Integer totalPage;
    // 總條數(shù)
    private Integer totalCount;
    
    // 無參構(gòu)造器（在調(diào)用的時(shí)候，可以直接傳遞值進(jìn)來，然后封裝數(shù)據(jù)）
    public PageBean(List<T> list, Integer currPage, Integer pageSize, Integer totalCount) {
        super();
        this.list = list;
        this.currPage = currPage;
        this.pageSize = pageSize;
        this.totalCount = totalCount;
    }

    public PageBean() {
        super();
    }




    public List<T> getList() {
        return list;
    }



    public void setList(List<T> list) {
        this.list = list;
    }

    public Integer getCurrPage() {
        return currPage;
    }

    public void setCurrPage(Integer currPage) {
        this.currPage = currPage;
    }

    public Integer getPageSize() {
        return pageSize;
    }

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

    public Integer getTotalPage() {
        return (int) Math.ceil((totalCount * 1.0 / pageSize));
    }

    public Integer getTotalCount() {
        return totalCount;
    }

    public void setTotalCount(Integer totalCount) {
        this.totalCount = totalCount;
    }

}

Controller層：

    public String findProByPage(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // 1. 獲取 cid 和 currPage 參數(shù)
        // 當(dāng)獲取到 cid 的時(shí)候，就可以知道是哪個(gè)分類
        // 獲取分類下所有的商品
        // 商品要展示，先告訴頁面每頁要展示多少條數(shù)據(jù)（寫死）
        String cid = request.getParameter("cid");
        int currPage = Integer.parseInt(request.getParameter("currPage"));
        // 設(shè)置每個(gè)分頁，固定顯示商品的條數(shù)
        int pageSize = 12;
        
        // 2. 調(diào)用 ProductService 執(zhí)行獲取分頁數(shù)據(jù)，需要返回一個(gè) PageBean
        PageBean<Product> pb = null;
        
        try {
            pb = ps.findProByPage(currPage, cid, pageSize);
        
            System.out.println("分頁對象：" + pb);
            
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        // 3. 將結(jié)果放入到 request 域中
        request.setAttribute("pb", pb);
        
        // 4. 請求轉(zhuǎn)發(fā)頁面
        return "product_list";
    }

Service層:

public PageBean<Product> findProByPage(int currPage, String cid, int pageSize) throws Exception {
        
        // 獲取分頁數(shù)據(jù) --- 所有相關(guān)的商品
        List<Product> proList = pdao.findProByPage(currPage, cid, pageSize);
        
        // 總數(shù)量
        int totalCount = pdao.getTotalCount(cid); 
        
        return new PageBean<Product>(proList, currPage, pageSize, totalCount);
    }

Dao層：

public class ProductDaoImpl implements ProductDao {
    
    private QueryRunner qr = new QueryRunner(DataSourceUtils.getDataSource());
    @Override
    public List<Product> findProByPage(int currPage, String cid, int pageSize) throws Exception {
        
        String sql = "select * from product where cid = ? limit ?, ?";
        
        return qr.query(sql, new BeanListHandler<>(Product.class), cid, (currPage - 1) * pageSize , pageSize);
        
        // limit(m, n)
        // m 是指記錄開始的 index，從 0 開始，表示第一條記錄
        // n 是指從第 m + 1 條開始，取 n 條。每頁固定的條數(shù)。
    }
    
    

    @Override
    public int getTotalCount(String cid) throws Exception {
        
        String sql = "select count(*) from product where cid = ?";
        
        return ((Long) qr.query(sql, new ScalarHandler(), cid)).intValue();
    }
}