day26(分页查询)

　　　　分页查询思路

　　　　　　　　

　　　　　　

问题:　　服务器向浏览器想用数据很多的时候可以对数据进行封装。

　　　　　domain层  封装数据　　　

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package com.baidu.domain;   import java.util.List;   public class PageBean {     //总页数     private int totalPage;     //总条数     private int totalCount;     //数据集合     private List<Product> list;     //当前页     private int currPage;     //页数显示信息数     private int pageSize;     public int getTotalPage() {         return totalPage;     }     public void setTotalPage(int totalPage) {         this.totalPage = totalPage;     }     public int getTotalCount() {         return totalCount;     }     public void setTotalCount(int totalCount) {         this.totalCount = totalCount;     }     public List<Product> getList() {         return list;     }     public void setList(List<Product> list) {         this.list = list;     }     public int getCurrPage() {         return currPage;     }     public void setCurrPage(int currPage) {         this.currPage = currPage;     }     public int getPageSize() {         return pageSize;     }     public void setPageSize(int pageSize) {         this.pageSize = pageSize;     }       }

　　

　　　　浏览器只需要使用项服务器发送页数，服务器会发送pageBean对象进行返回。

　　　　Service层  处理业务

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public PageBean getPageListProduct(int currPage) throws Exception {     PageBean pb=new PageBean();     //设置页面数     pb.setPageSize(10);     pb.setCurrPage(currPage);     //获取集合列表     List<Product> list = pd.getPageListProduct(pb);           pb.setList(list);     for (Product product : pb.getList()) {         System.out.println(product);     }     //获取总条数     int l = (int) pd.getPageProductAcount();     pb.setTotalCount(l);     //获取总页数     if (l%10==0) {         pb.setTotalPage(l/10);     }else{         pb.setTotalPage((l/10)+1);     }     return pb;       }

　　dao层

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public List<Product> getPageListProduct(PageBean pb) throws SQLException {     QueryRunner qr=new QueryRunner(JDBCUtils.getDataSource());      String sql="select * from product limit ?,?";     List<Product> list = qr.query(sql, new BeanListHandler<Product>(Product.class),(pb.getCurrPage()-1)*pb.getPageSize(),pb.getPageSize());     return list; }

　　

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public long getPageProductAcount() throws SQLException {         QueryRunner qr=new QueryRunner(JDBCUtils.getDataSource());          String sql="Select count(*) from product";         long l = (Long)qr.query(sql, new ScalarHandler());         return l;               }

　　　　JDBCUtils

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public class JDBCUtils {     private static final ComboPooledDataSource cpd=new ComboPooledDataSource();           /**      * 获取连接对象      * @return      * @throws SQLException      */     public static Connection getConnection() throws SQLException{         Connection conn = cpd.getConnection();         return conn;     }     /**      * 获取数据源      * @return      */     public static DataSource getDataSource(){         return cpd;     } }