案例6-商品的分页显示

时间 2019-11-24

标签案例商品分页显示繁體版

原文原文链接

1 预期效果

2 pageBean类

package www.test.vo;

import java.util.ArrayList;
import java.util.List;

public class PageBean<T> { // 1 当前页 private int currentPage; // 2 当前页显示的条数 private int currentCount; // 3 总条数 private int totalCount; // 4 总页数 private int totalPage; // 5 每页显示的数据 private List<T> productList = new ArrayList<T>(); public int getCurrentPage() {
        return currentPage;
    }

    public void setCurrentPage(int currentPage) {
        this.currentPage = currentPage;
    }

    public int getCurrentCount() {
        return currentCount;
    }

    public void setCurrentCount(int currentCount) {
        this.currentCount = currentCount;
    }

    public int getTotalCount() {
        return totalCount;
    }

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

    public int getTotalPage() {
        return totalPage;
    }

    public void setTotalPage(int totalPage) {
        this.totalPage = totalPage;
    }

    public List<T> getProductList() {
        return productList;
    }

    public void setProductList(List<T> productList) {
        this.productList = productList;
    }
}

3 web层

package www.test.web;

import java.io.IOException;
import java.sql.SQLException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import www.test.domain.Product;
import www.test.service.ProductService;
import www.test.vo.PageBean;

public class ProductListServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        ProductService service = new ProductService();
        
        //模拟当前是第一页
        String currentPageStr = request.getParameter("currentPage");
          //若是是直接访问productList的话，让currentPageStr=1； if(currentPageStr==null) currentPageStr="1"; int currentPage = Integer.parseInt(currentPageStr);
        //认为每页显示12条
        int currentCount = 12;
        
        PageBean<Product> pageBean = null;
        try {
            pageBean = service.findPageBean(currentPage,currentCount);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        
        request.setAttribute("pageBean", pageBean);
        
        request.getRequestDispatcher("/product_list.jsp").forward(request, response);
        
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}

4 service层

package www.test.service;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import www.test.dao.ProductDao;
import www.test.domain.Product;
import www.test.vo.PageBean;

public class ProductService {

    public List<Product> findAllProduct() throws SQLException {
        ProductDao dao = new ProductDao();
        return dao.findAllProduct();
    }
    //分页操做
    public PageBean findPageBean(int currentPage,int currentCount) throws SQLException  {
        
        ProductDao dao = new ProductDao();
        
        //目的：就是想办法封装一个PageBean 并返回 PageBean pageBean = new PageBean(); //一、当前页private int currentPage;  pageBean.setCurrentPage(currentPage); //二、当前页显示的条数private int currentCount;  pageBean.setCurrentCount(currentCount); //三、总条数private int totalCount; int totalCount = dao.getTotalCount(); pageBean.setTotalCount(totalCount); //四、总页数private int totalPage; /* * 总条数 当前页显示的条数 总页数 * 10 4 3 * 11 4 3 * 12 4 3 * 13 4 4 * * 公式：总页数=Math.ceil(总条数/当前显示的条数) * */ int totalPage = (int) Math.ceil(1.0*totalCount/currentCount); pageBean.setTotalPage(totalPage); //五、每页显示的数据private List<T> productList = new ArrayList<T>(); /* * 页数与limit起始索引的关系 * 例如 每页显示4条 * 页数 其实索引 每页显示条数 * 1 0 4 * 2 4 4 * 3 8 4 * 4 12 4 * * 索引index = (当前页数-1)*每页显示的条数 * */ int index = (currentPage-1)*currentCount; List<Product> productList = dao.findProductListForPageBean(index,currentCount); pageBean.setProductList(productList); return pageBean;
    }

}

5 dao层

package www.test.dao;

import java.sql.SQLException;
import java.util.List;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;

import www.test.domain.Product;
import www.test.utils.DataSourceUtils;

public class ProductDao {

    public List<Product> findAllProduct() throws SQLException {
        return new QueryRunner(DataSourceUtils.getDataSource()).query("select * from product", new BeanListHandler<Product>(Product.class));
    }

    //得到所有的商品条数
    public int getTotalCount() throws SQLException {
        QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
        String sql = "select count(*) from product";
        Long query = (Long) runner.query(sql, new ScalarHandler());
        return query.intValue();
    }

    //得到分页的商品数据
    public List<Product> findProductListForPageBean(int index,int currentCount) throws SQLException {
        QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
        String sql = "select * from product limit ?,?"; return runner.query(sql, new BeanListHandler<Product>(Product.class), index,currentCount);
    }

}

6 product_list.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>会员登陆</title>
<link rel="stylesheet" href="css/bootstrap.min.css" type="text/css" />
<script src="js/jquery-1.11.3.min.js" type="text/javascript"></script>
<script src="js/bootstrap.min.js" type="text/javascript"></script>
<!-- 引入自定义css文件 style.css -->
<link rel="stylesheet" href="css/style.css" type="text/css" />

<style>
body {
    margin-top: 20px;
    margin: 0 auto;
    width: 100%;
}

.carousel-inner .item img {
    width: 100%;
    height: 300px;
}
</style>
</head>

<body>


    <!-- 引入header.jsp -->
    <jsp:include page="/header.jsp"></jsp:include>


    <div class="row" style="width: 1210px; margin: 0 auto;">
        <div class="col-md-12">
            <ol class="breadcrumb">
                <li><a href="#">首页</a></li>
            </ol>
        </div>
        
        <c:forEach items="${pageBean.productList }" var="product">
            <div class="col-md-2" style="height:250px">
                <a href="product_info.htm"> 
                    <img src="${pageContext.request.contextPath }/${product.pimage}" width="170" height="170" style="display: inline-block;">
                </a>
                <p>
                    <a href="product_info.html" style='color: green'>${product.pname }</a>
                </p>
                <p>
                    <font color="#FF0000">商城价：&yen;${product.shop_price }</font>
                </p>
            </div>
        </c:forEach>

        

        

    </div>

    <!--分页 -->
    <div style="width: 380px; margin: 0 auto; margin-top: 50px;">
        <ul class="pagination" style="text-align: center; margin-top: 10px;">
            <!-- 上一页 -->
            <!-- 判断当前页是不是第一页 -->
            <c:if test="${pageBean.currentPage==1 }">
                <li class="disabled">
                    <a href="javascript:void(0);" aria-label="Previous">
                        <span aria-hidden="true">&laquo;</span>
                    </a>
                </li>
            </c:if>
            <c:if test="${pageBean.currentPage!=1 }">
                <li>
                    <a href="${pageContext.request.contextPath }/productList?currentPage=${pageBean.currentPage-1}" aria-label="Previous">
                        <span aria-hidden="true">&laquo;</span>
                    </a>
                </li>
            </c:if>    
            
            
            
        
            <c:forEach begin="1" end="${pageBean.totalPage }" var="page"> <!-- 判断当前页 --> <c:if test="${pageBean.currentPage==page }"> <li class="active"><a href="javascript:void(0);">${page}</a></li> </c:if> <c:if test="${pageBean.currentPage!=page }"> <li><a href="${pageContext.request.contextPath }/productList?currentPage=${page}">${page}</a></li> </c:if> </c:forEach>
            
            <!-- 判断当前页是不是最后一页 -->
            <c:if test="${pageBean.currentPage==pageBean.totalPage }"> <li class="disabled"> <a href="javascript:void(0);" aria-label="Next"> <span aria-hidden="true">&raquo;</span> </a> </li> </c:if> <c:if test="${pageBean.currentPage!=pageBean.totalPage }"> <li> <a href="${pageContext.request.contextPath }/productList?currentPage=${pageBean.currentPage+1}" aria-label="Next"> <span aria-hidden="true">&raquo;</span> </a> </li> </c:if>
        
        </ul>
    </div>
    <!-- 分页结束 -->

    <!--商品浏览记录-->
    <div
        style="width: 1210px; margin: 0 auto; padding: 0 9px; border: 1px solid #ddd; border-top: 2px solid #999; height: 246px;">

        <h4 style="width: 50%; float: left; font: 14px/30px 微软雅黑">浏览记录</h4>
        <div style="width: 50%; float: right; text-align: right;">
            <a href="">more</a>
        </div>
        <div style="clear: both;"></div>

        <div style="overflow: hidden;">

            <ul style="list-style: none;">
                <li
                    style="width: 150px; height: 216; float: left; margin: 0 8px 0 0; padding: 0 18px 15px; text-align: center;"><img
                    src="products/1/cs10001.jpg" width="130px" height="130px" /></li>
            </ul>

        </div>
    </div>


    <!-- 引入footer.jsp -->
    <jsp:include page="/footer.jsp"></jsp:include>

</body>

</html>

7 注意事项

1 取消超链 javascript:void(0);javascript

2 分页查询css

3 记住pageBean类html