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Shop项目--4. 分页显示商品的，与分页跳转，上一页，下一页product_list.jsp

2017-11-23 18:12 399 查看

分析：

1.分页显示商品，需要pageBean对象，里面维护着 currentPage,currentCount,totalPage,totalCount List<?>

List<Product>装的是根据cid查询到的商品列表，在后台封装好pageBean对象，就能在前台编辑分页显示。

2.分页显示，显示其实就是执行一个功能取到该页的pageBean对象，该功能需要获取当前页currentPage，与cid参数。注意传递

3.每个分页显示的商品是有限的，所以dao层查询的商品列表要有开始索引index与每页显示的数量currentPage。

4.上一页，下一页，还有其他页跳转，需要判断是否为当前页

准备：

pageBean类

步骤：

从head.jsp 进入content+="<li><a href='${pageContext.request.contextPath}/product?method=productListByCid&cid="+data[i].cid+"'>"+data[i].cname+"</a></li>"

1.在web层获取cid，currentPage（如为空，设置为1）与设置currentCount并传递到service层。

2.在service层封装pageBean

1)currentPage

2)currentCount

3)totalCount（根据cid传递到dao层查找）

4)totalPage（总页数除以当前页）

5)List<product>（根据cid index 还有显示数量传递到dao层获取）

3.web层把pageBean cid 传到request域并转发到 product_list.jsp页面

在product_list.jsp前端页面

4.根据pageBean.totalPage 遍历显示所有的分页page

5.判断当前页currentPage是否为page，如是则不能跳转，设置为javascript：如不是则可以跳转携带cid currentPage 执行分页显示功能

6.同理判断当前页是否为第一页或最后一页，携带cid currentPage 执行分页功能

header.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<!-- 登录 注册 购物车... -->
<div class="container-fluid">
<div class="col-md-4">
<img src="img/logo2.png" />
</div>
<div class="col-md-5">
<img src="img/header.png" />
</div>
<div class="col-md-3" style="padding-top:20px">
<ol class="list-inline">
<li><a href="login.jsp">登录</a></li>
<li><a href="register.jsp">注册</a></li>
<li><a href="cart.jsp">购物车</a></li>
<li><a href="order_list.jsp">我的订单</a></li>
</ol>
</div>
</div>

<!-- 导航条 -->
<div class="container-fluid">
<nav class="navbar navbar-inverse">
<div class="container-fluid">
<!-- Brand and toggle get grouped for better mobile display -->
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="#">首页</a>
</div>

<!-- 商品分类列表 ajax-->
<script type="text/javascript">
$(function(){
$.post(
"${pageContext.request.contextPath}/product?method=category",
function(data){
//[{"cid":"xxx","cname":"xxx"},{},{},{},{}]
var content ="";
for (var i = 0; i < data.length; i++) {
//拼接字符串后，内部双引号必须改为单引号
//a标签链接为根据cid查找商品的一个servlet，注意拼接字符串
content+="<li><a href='${pageContext.request.contextPath}/product?method=productListByCid&cid="+data[i].cid+"'>"+data[i].cname+"</a></li>"
}
//添加li到ul中
$("#categoryUl").html(content);
},
"json"
);
});
</script>
<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
<ul class="nav navbar-nav" id="categoryUl">
<!-- <li class="active"><a href="product_list.htm">手机数码<span class="sr-only">(current)</span></a></li>
<li><a href="#">电脑办公</a></li>
<li><a href="#">电脑办公</a></li>
<li><a href="#">电脑办公</a></li>
-->				</ul>
<form class="navbar-form navbar-right" role="search">
<div class="form-group">
<input type="text" class="form-control" placeholder="Search">
</div>
<button type="submit" class="btn btn-default">Submit</button>
</form>
</div>
</div>
</nav>
</div>

ProductServlet

package com.itheima.web.servlet;

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

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

import com.google.gson.Gson;
import com.itheima.domain.Category;
import com.itheima.domain.PageBean;
import com.itheima.domain.Product;
import com.itheima.service.ProductService;
import com.itheima.utils.JedisPoolUtils;

import redis.clients.jedis.Jedis;

public class ProductServlet extends BaseServlet {

//根据商品分类的cid获取商品，分页显示功能
public void productListByCid(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
//获取商品分类的cid
String cid = request.getParameter("cid");
//获取当前页,如果没有当前页，设置为第一页
String currentPageStr = request.getParameter("currentPage");
if(currentPageStr==null) {
currentPageStr ="1";
}
//当前页，与当前显示数
int currentPage = Integer.parseInt(currentPageStr);
int currentCount =12;
//传递到service层，pageBean
ProductService service = new ProductService();
PageBean<Product>  pageBean =  service.findPageBeanByCid(cid,currentPage,currentCount);
//传递pageBean 与 cid 等待分页下一次执行该功能时候使用
request.setAttribute("cid", cid);
request.setAttribute("pageBean", pageBean);
request.getRequestDispatcher("/product_list.jsp").forward(request, response);
}

//获取商品的分类列表
public void category(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {

ProductService service = new ProductService();
//先从缓存中查询是否有categoryList，没有再从数据库中查询
//1.获得jedis对象连接redis数据库
Jedis jedis = JedisPoolUtils.getJedis();
String categoryListJson = jedis.get("categoryListJson");
//2.判断categoryList是否为空
if(categoryListJson==null) {
System.out.println("缓存没有数据，查找数据库");
//准备分类数据
List<Category> categoryList = service.findCategory();
Gson gson = new Gson();
categoryListJson = gson.toJson(categoryList);
jedis.set("categoryListJson", categoryListJson);
}
//有中文，所以要解决乱码问题
response.setContentType("text/html;charset=UTF-8");
response.getWriter().write(categoryListJson);
}

//首页动态获取最新商品和热门商品
public void index(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
ProductService service = new ProductService();
//获取热门商品
List<Product> hotProList = service.findHotProduct();
//获取最新商品
List<Product> newProList = service.findNewProduct();
//传递到request域，并转发到index.jsp
request.setAttribute("hotProList", hotProList);
request.setAttribute("newProList", newProList);
request.getRequestDispatcher("/index.jsp").forward(request, response);

}

}

ProductService

package com.itheima.service;

import java.sql.
4000
SQLException;
import java.util.List;

import com.itheima.dao.ProductDao;
import com.itheima.domain.Category;
import com.itheima.domain.PageBean;
import com.itheima.domain.Product;

public class ProductService {

//获取热门商品
public List<Product> findHotProduct() {
ProductDao dao = new ProductDao();
List<Product> hotProList = null;
try {
hotProList = dao.findHotProduct();
} catch (SQLException e) {
e.printStackTrace();
}
return hotProList;
}

//获取最新商品
public List<Product> findNewProduct() {
ProductDao dao = new ProductDao();
List<Product> newProList = null;
try {
newProList = dao.findNewProduct();
} catch (SQLException e) {
e.printStackTrace();
}
return newProList;
}

//获取商品列表
public List<Category> findCategory() {
ProductDao dao = new ProductDao();
List<Category> categoryList = null;
try {
categoryList = dao.findCategory();
} catch (SQLException e) {
e.printStackTrace();
}
return categoryList;
}

//根据cid获取pagebean
public PageBean findPageBeanByCid(String cid, int currentPage, int currentCount) {
ProductDao dao = new ProductDao();
PageBean<Product> pageBean = new PageBean<Product>();
//当前页
pageBean.setCurrentPage(currentPage);
//当前页显示条数
pageBean.setCurrentCount(currentCount);
//总共条数
int totalCount = 0;
try {
totalCount = dao.findtotalCount(cid);
} catch (SQLException e) {
e.printStackTrace();
}
pageBean.setTotalCount(totalCount);
//总共页数
// math.ceil向上取整 该方法内的是double类型 所以乘以1.0
int totalPage = (int) Math.ceil(1.0*totalCount/currentCount);
pageBean.setTotalPage(totalPage);
//商品列表,计算从多少角标开始取
int index = (currentPage-1)*currentCount;
List<Product> productList = null;
try {
productList = dao.findProductListByCid(cid,index,currentCount);
} catch (SQLException e) {
e.printStackTrace();
}
pageBean.setList(productList);
return pageBean;
}

}

ProductDao

package com.itheima.dao;

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

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

import com.itheima.domain.Category;
import com.itheima.domain.Product;
import com.itheima.utils.DataSourceUtils;

public class ProductDao {

// 获取热门商品
public List<Product> findHotProduct() throws SQLException {
QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
String sql = "select * from product where is_hot=? limit ?,?";
List<Product> query = runner.query(sql, new BeanListHandler<Product>(Product.class), 1,0,9);
return query;
}

//获取最新商品
public List<Product> findNewProduct() throws SQLException {
QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
//此处注意使用order by pdate desc 时间最大开始选择
String sql ="select * from product order by pdate desc limit ?,?";
List<Product> query = runner.query(sql, new BeanListHandler<Product>(Product.class), 0,9);
return query;
}

//获取商品分类列表
public List<Category> findCategory() throws SQLException {
QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
String sql ="select * from category";
List<Category> query = runner.query(sql, new BeanListHandler<Category>(Category.class));
return query;
}

// 根据商品分类的cid获取商品
public List<Product> findProductListByCid(String cid, int index, int currentPage) throws SQLException {
QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
String sql = "select * from product where cid=? limit ?,?";
List<Product> query = runner.query(sql, new BeanListHandler<Product>(Product.class), cid,index,currentPage);
return query;
}

//根据cid查找商品总条数
public int findtotalCount(String cid) throws SQLException {
QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
String sql ="select count(*) from product where cid=?";
Long query = (Long) runner.query(sql, new ScalarHandler(), cid);
//Long转为int
return query.intValue();
}

//根据pid查找商品
public Product findProductByPid(String pid) throws SQLException {
QueryRunner runner = new QueryRunner(DataSourceUtils.getDataSource());
String sql = "select * from product where pid=?";
Product query = runner.query(sql, new BeanHandler<Product>(Product.class), pid);
return query;
}

}

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>会员登录</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>

<!-- 根据cid分类的商品列表 -->
<c:forEach items="${pageBean.list }" var="product">
<div class="col-md-2" style="height: 250px">
<a href="product_info.htm"> <img src="${product.pimage }"
width="170" height="170" style="display: inline-block;">
</a>
<p>
<a href="product_info.html" style='color: green'>${product.pname }</a>
</p>
<p>
<font color="#FF0000">商城价：¥${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 -->
<!-- 判断当前页是否第一页 -->
<c:if test="${pageBean.currentPage==1}">
<li class="disabled">
<!-- 不能点击的设置 javascript:void(0);-->
<a href="javascript:void(0);" aria-label="Previous">
<span aria-hidden="true">«</span>
</a>
</li>
</c:if>
<c:if test="${pageBean.currentPage!=1}">
<li >
<a href="${pageContext.request.contextPath }/product?method=productListByCid&cid=${cid}¤tPage=${pageBean.currentPage-1}" aria-label="Previous">
<span aria-hidden="true">«</span>
</a>
</li>
</c:if>

<!-- 分页显示代码 -->
<!-- 1.遍历，显示所有分页 -->
<c:forEach begin="1" end="${pageBean.totalPage }" var="page">
<!--2.判断是否当前页  -->
<c:if test="${pageBean.currentPage==page }">
<li class="active"><a href="#">${page }</a></li>
</c:if>
<c:if test="${pageBean.currentPage!=page }">
<!--3. 跳转到另外一页，需要携带cid与page  -->
<li><a href="${pageContext.request.contextPath}/product?method=productListByCid&cid=${cid}¤tPage=${page}">${page }</a></li>
</c:if>
</c:forEach>

<!-- 下一页 -->
<!-- 判断是否最后一页 -->
<c:if test="${pageBean.currentPage==pageBean.totalPage }">
<li class="disabled">
<a href="javascript:" aria-label="Next">
<span aria-hidden="true">»</span>
</a>
</li>
</c:if>
<c:if test="${pageBean.currentPage!=pageBean.totalPage }">
<li>
<a href="${pageContext.request.contextPath }/product?method=productListByCid&cid=${cid}¤tPage=${pageBean.currentPage+1}" aria-label="Next">
<span aria-hidden="true">»</span>
</a>
</li>
</c:if>

<!-- <li class="disabled"><a href="#" aria-label="Previous"><span
aria-hidden="true">«</span></a></li>
<li class="active"><a href="#">1</a></li>
<li><a href="#">2</a></li>
<li><a href="#">3</a></li>
<li><a href="#">4</a></li>
<li><a href="#">5</a></li>
<li><a href="#">6</a></li>
<li><a href="#">7</a></li>
<li><a href="#">8</a></li>
<li><a href="#">9</a></li>
<li><a href="#" aria-label="Next"> <span aria-hidden="true">»</span>
</a></li> -->
</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>

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