10.按类别查询分页
提交方式：
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=文学">文学</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=生活">生活</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=计算机">计算机</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=外语">外语</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=经营">经管</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=励志">励志</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=社科">社科</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=学术">学术</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=少儿">少儿</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=艺术">艺术</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=原版">原版</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=科技">科技</a>
<a
href="${pageContext.request.contextPath}/product?method=findByPage2&category=考试">考试</a>
三层架构：
ProductServlet
/**
* 根据类别查询并分页
* @param request
* @param response
* @throws ServletException
* @throws IOException
*/
public void findByPage2(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取分类
String category=request.getParameter("category");
System.out.println(category);
//一般情况下，服务器默认的编码是“iso8859-1”，所以我们需要数据还原，然后再转换成UTF-8的形式
//如果要调用request.setCharacterEncoding进行编码设置，一定要在任何参数被访问之前调用。
//if(category!=null){
// category=new String(category.getBytes("iso8859-1"),"utf-8");
//}
//获取页码
int pageCode=getPageCode(request);
//每页显示的记录条数
int pageSize=4;
//调用业务层
ProductService ps=new ProductService();
//分类分页的查询
PageBean page=ps.findByPage(pageCode,pageSize,category);
//获取连接，设置到page的对象中
page.setUrl(getUrl(request));
request.setAttribute("page", page);
request.getRequestDispatcher("/product_list.jsp").forward(request, response);
}
ProductService
/**
* 根据类别查询并分页
* @param pageCode
* @param pageSize
* @param category
* @return
*/
public PageBean findByPage(int pageCode, int pageSize, String category) {
ProductDao dao=new ProductDao();
return dao.findByPage(pageCode,pageSize,category);
}
ProductDao
/**
* 根据类别查询并分页
* @param pageCode
* @param pageSize
* @param category
* @return
*/
public PageBean findByPage(int pageCode, int pageSize, String category) {
//存储cansh
List<Object> list=new ArrayList();
PageBean<Product> page=new PageBean<Product>();
page.setPageCode(pageCode);
page.setPageSize(pageSize);
QueryRunner runner=new QueryRunner(MyJdbcUtils.getDataSource());
String countSql=null;
String selSql=null;
if(category!=null){
countSql="select count(*) from products where category=?";
selSql="select * from products where category=? limit ?,?";
list.add(category);
}else{
countSql="select count(*) from products ";
selSql="select * from products limit ?,?";
}
try {
//查询总记录的条数
long totalCount=(long) runner.query(countSql, new ScalarHandler(),list.toArray());
//设置条数
page.setTotalCount((int)totalCount);
list.add((pageCode-1)*pageSize);
list.add(pageSize);
//查询每页显示的条数
List<Product> beanList=runner.query(selSql, new BeanListHandler<Product>(Product.class),list.toArray());
page.setBeanList(beanList);
} catch (SQLException e) {
e.printStackTrace();
}
return page;
}
javabean:
/**
* 分页的javabean
* @author mjl
*
*/
public class PageBean<T> {
//当前页
private int pageCode;
//总页数=总记录数/每页 显示的条数
//private int totalPage;
//总记录数
private int totalCount;
//每页显示的条数
private int pageSize;
//每页显示的数据
private List<T> beanList;
//新添加一个属性，作为分页的条件出现的
private String url;
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
public int getPageCode() {
return pageCode;
}
public void setPageCode(int pageCode) {
this.pageCode = pageCode;
}
public int getTotalPage() {
int totalPage=totalCount/pageSize;
if(totalCount % pageSize ==0){
return totalPage;
}else{
return totalPage+1;
}
}
/*
//不用自己设置值的，这是计算出来的
public void setTotalPage(int totalPage) {
this.totalPage = totalPage;
}*/
//获取总页数
public int getTotalCount() {
//可以计算
return totalCount;
}
public void setTotalCount(int totalCount) {
this.totalCount = totalCount;
}
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public List<T> getBeanList() {
return beanList;
}
public void setBeanList(List<T> beanList) {
this.beanList = beanList;
}
}
product_list.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>bookStore列表</title>
<%--导入css --%>
<link rel="stylesheet" href="css/main.css" type="text/css" />
</head>
<body class="main">
<jsp:include page="head.jsp" />
<jsp:include page="menu_search.jsp" />
<div id="divpagecontent">
<table width="100%" border="0" cellspacing="0">
<tr>
<td>
<div style="text-align:right; margin:5px 10px 5px 0px">
<a href="index.jsp">首页</a> > 计算机 > 图书列表
</div>
<table cellspacing="0" class="listcontent">
<tr>
<td>
<h1>商品目录</h1>
<hr />
<h1>计算机</h1> 共${page.totalCount }种商品
<hr />
<div style="margin-top:20px; margin-bottom:5px">
<img src="images/productlist.gif" width="100%" height="38" />
</div>
<table cellspacing="0" class="booklist">
<!-- 一页只有四个 对象，所以遍历4次 -->
<tr>
<c:forEach var="p" items="${page.beanList }">
<td>
<div class="divbookpic">
<p>
<a href="${pageContext.request.contextPath }/product?method=findInfo&pid=${p.pid}">
<img src="bookcover/101.jpg" width="115" height="129" border="0" />
</a>
</p>
</div>
<div class="divlisttitle">
<a href="${pageContext.request.contextPath }/product?method=findInfo&pid=${p.pid}">
书名:${p.pname }<br />售价:${p.price }
</a>
</div>
</td>
</c:forEach>
</tr>
</table>
<div class="pagination">
<ul>
<c:if test="${page.pageCode>1 }">
<li class="disablepage">
<a href="${page.url }&pc=${page.pageCode-1}">上一页</a>
<%-- <a href="${pageContext.request.contextPath }/product?method=findByPage&pc=${page.pageCode-1}" >上一页</a> --%>
</li>
</c:if>
<!--也可以产生这种循环 for(int i=1;i<=10;i++){} -->
<%--
目的：控制begin和end的值
逻辑：
当总页数<=10,说明一共不超过10页，让begin=1,end=总页数
当总页数>10,让begin=pageCode-5,end=pageCode+4
头溢出：
如果当前页=3，begin=3-5=-2
如果begin<1,让begin=1,end=10
尾溢出：
如果end>总页数，让end=总页数，begin=总页数-9
--%>
<!-- 编写逻辑 判断开始页码结束页码-->
<c:choose>
<c:when test="${page.totalPage<=10 }">
<c:set var="begin" value="1" ></c:set>
<c:set var="end" value="${page.totalPage }"></c:set>
</c:when>
<c:otherwise>
<c:set var="begin" value="${page.pageCode-5 }" ></c:set>
<c:set var="end" value="${page.pageCode+4 }"></c:set>
<!-- 判断头溢出 -->
<c:if test="${begin<1 }">
<c:set var="begin" value="1" ></c:set>
<c:set var="end" value="10"></c:set>
</c:if>
<!-- 判断尾溢出 -->
<c:if test="${end>page.totalPage }">
<c:set var="begin" value="${page.totalPage-9 }" ></c:set>
<c:set var="end" value="${page.totalPage }"></c:set>
</c:if>
</c:otherwise>
</c:choose>
<c:forEach var="i" begin="${begin }" end="${end }" step="1">
<!-- 当前页==i -->
<c:if test="${page.pageCode==i }">
<li class="currentpage">${i }</li>
</c:if>
<c:if test="${page.pageCode!=i }">
<li>
<%-- <a href="${pageContext.request.contextPath }/product?method=findByPage&pc=${i}">${i }</a> --%>
<a href="${page.url }&pc=${i}">${i }</a>
</li>
</c:if>
</c:forEach>
<c:if test="${page.pageCode<page.totalPage }">
<li class="nextpage">
<a href="${page.url }&pc=${page.pageCode+1}">下一页</a>
<%-- <a href="${pageContext.request.contextPath }/product?method=findByPage&pc=${page.pageCode+1}">下一页</a> --%>
</li>
</c:if>
</ul>
</div>
</td>
</tr>
</table>
</td>
</tr>
</table>
</div>
<jsp:include page="foot.jsp" />
</body>
</html>
获取图书详细信息：
ProductServlet:
/**
* 查询书的详细的信息
* @param request
* @param response
* @throws ServletException
* @throws IOException
*/
public void findInfo(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//接收Id
String pid=request.getParameter("pid");
//
ProductService ps=new ProductService();
Product p=ps.findById(pid);
request.setAttribute("p", p);
request.getRequestDispatcher("/product_info.jsp").forward(request, response);
}
product_info:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>电子书城</title>
<link rel="stylesheet" href="css/main.css" type="text/css" />
</head>
<body class="main">
<jsp:include page="head.jsp" />
<jsp:include page="menu_search.jsp" />
<div id="divpagecontent">
<table width="100%" border="0" cellspacing="0">
<tr>
<td><div style="text-align:right; margin:5px 10px 5px 0px">
<a href="index.html">首页</a> > <a
href="product_list.html"> ${p.category }</a> > ${p.pname }
</div>
<table cellspacing="0" class="infocontent">
<tr>
<td><img src="ad/page_ad.jpg" width="645" height="84" />
<table width="100%%" border="0" cellspacing="0">
<tr>
<td width="30%">
<div class="divbookcover">
<p>
<img src="bookcover/101.jpg"
width="213" height="269" border="0" />
</p>
</div>
<div style="text-align:center; margin-top:25px">
<!-- 点击购买 -->
<a href="${pageContext.request.contextPath }/cart?method=addToCart&pid=${p.pid}">
<img src="images/buybutton.gif" border="0" />
</a>
</div>
</td>
<td style="padding:20px 5px 5px 5px">
<img src="images/miniicon3.gif" width="16" height="13" />
<font class="bookname"> ${p.pname }</font>
<hr />售价：<font color="#FF0000">${p.price }</font>
<hr /> 类别：${p.category }
<hr />
<p>
<b>内容简介：</b>
</p> ${p.description }
</td>
</tr>
</table>
</td>
</tr>
</table>
</td>
</tr>
</table>
</div>
<jsp:include page="foot.jsp" />
</body>
</html>
点击购买，跳转到购物车
JavaBean:
购物项：
/**
* 购物项
* 包含 购买的数量 小计 商品
* @author mjl
*
*/
public class CartItem {
//编写属性
//商品
private Product product;
//购买的数量
private int buyNum;
//小计
private double subtotal;
public Product getProduct() {
return product;
}
public void setProduct(Product product) {
this.product = product;
}
public int getBuyNum() {
return buyNum;
}
public void setBuyNum(int buyNum) {
this.buyNum = buyNum;
}
//小计是算出来的，干掉set，留get
public double getSubtotal() {
return product.getPrice()*buyNum;
}
/*public void setSubtotal(double subtotal) {
this.subtotal = subtotal;
}*/
}
购物车：
/**
* 购物车
* 购物车包含：多个购物项 合计
* @author mjl
*
*/
public class Cart {
//合计=小计的和
private double total;
//包含多个购物项(list删除需要遍历，map.remove(key),所以map更容易操作)
private Map<String,CartItem> map=new HashMap();
//
public double getTotal() {
double t=0;
//获取map集合中所有的购物项
for(String key:map.keySet()){
CartItem item=map.get(key);
//获取购物项的小计
t+=item.getSubtotal();
}
return t;
}
public void setTotal(double total) {
this.total = total;
}
public Map<String, CartItem> getMap() {
return map;
}
public void setMap(Map<String, CartItem> map) {
this.map = map;
}
//提供方法：把购买的购物项保存到map集合中
public void addCart(CartItem item){
//把购物项存入到购物车中，(其实就是向map集合中存入)
//map.put(item.getProduct().getPid(), item);
/**
* 如果购买的是相同的书，数量+1
* 如果购买的不同的书，直接存入到map集合中
*/
//获取商品的主键
String pid=item.getProduct().getPid();
//判断,map集合中是否包含该主键
if(map.containsKey(pid)){
//之前存入过一次了,直接更新数量就可以了
CartItem hisItem=map.get(pid);
hisItem.setBuyNum(hisItem.getBuyNum()+item.getBuyNum());
}else{
//说明第一次存入该商品
map.put(pid, item);
}
}
}
CartServlt:
public class CartServlet extends BaseServlet {
/**
* 把购买的商品添加到购物车中
* @param request
* @param response
* @throws ServletException
* @throws IOException
*/
public void addToCart(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
/**
* 1.先得准备商品
* 2.准备购物项
* 3.把购物项添加到购物车中
*/
//1.先得准备商品
String pid=request.getParameter("pid");
//查询
ProductService ps=new ProductService();
Product product=ps.findById(pid);
//2.准备购物项
CartItem item=new CartItem();
item.setProduct(product);
item.setBuyNum(1);
//3.把购物项添加到购物车中,购物车存到session中
//Cart cart=new Cart();
Cart cart=getCart(request);
cart.addCart(item);
//跳转到购物车的页面，显示数据
//session是会话级别，多次请求响应，用重定向
response.sendRedirect(request.getContextPath()+"/cart.jsp");
}
/**
* 获取购物车
* @param request
* @return
*/
public Cart getCart(HttpServletRequest request){
/**
* 如果是第一次访问，没有购物车，创建购物车，存入到session中
* 如果不是第一次访问，直接从session中获取购物车
*/
HttpSession session=request.getSession();
//获取购物车
Cart cart=(Cart) session.getAttribute("cart");
//如果是第一次，cart=null
if(cart==null){
//创建购物车
cart=new Cart();
//非常重要，存购物车
session.setAttribute("cart", cart);
}
return cart;
}
}
点击x号，删除商品。点击+ -号，增加减少商品
cart.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>电子书城</title>
<link rel="stylesheet" href="css/main.css" type="text/css" />
<script type="text/javascript">
//点击+号，添加购买数量
function addCount(pid,count){
window.location.href="${pageContext.request.contextPath}/cart?method=addCount&pid="+pid+"&count="+count;
}
//点击-号，减少购买数量
function removeCount(pid,count){
window.location.href="${pageContext.request.contextPath}/cart?method=removeCount&pid="+pid+"&count="+count;
}
</script>
</head>
<body class="main">
<jsp:include page="head.jsp" />
<jsp:include page="menu_search.jsp" />
<div id="divpagecontent">
<table width="100%" border="0" cellspacing="0">
<tr>
<td><div style="text-align:right; margin:5px 10px 5px 0px">
<a href="index.html">首页</a> > 购物车
</div>
<table cellspacing="0" class="infocontent">
<tr>
<td><img src="ad/page_ad.jpg" width="666" height="89" />
<table width="100%" border="0" cellspacing="0">
<tr>
<td><img src="images/buy1.gif" width="635" height="38" />
</td>
</tr>
<tr>
<td>
<table cellspacing="1" class="carttable">
<tr>
<td width="10%">序号</td>
<td width="30%">商品名称</td>
<td width="10%">价格</td>
<td width="20%"> 数量</td>
<td width="10%">库存</td>
<td width="10%">小计</td>
<td width="10%">取消</td>
</tr>
</table>
<!-- for(Entry entry:map){} Map<String, CartItem>-->
<c:forEach var="entry" items="${cart.map }" varStatus="vs">
<table width="100%" border="0" cellspacing="0">
<tr>
<td width="10%">${vs.count }</td>
<td width="30%">${entry.value.product.pname }</td>
<td width="10%">${entry.value.product.price}</td>
<td width="20%">
<!-- 加减号更新数量 -->
<input type="button" value='-' style="width:20px" onclick="removeCount('${entry.value.product.pid}','${entry.value.buyNum-1 }');">
<!-- 中间显示的数量 -->
<input name="text" type="text" value="${entry.value.buyNum }" style="width:40px;text-align:center" />
<input type="button" value='+' style="width:20px" onclick="addCount('${entry.value.product.pid}','${entry.value.buyNum+1 }');">
</td>
<td width="10%">${entry.value.product.pnum }</td>
<td width="10%">${entry.value.subtotal}</td>
<td width="10%">
<a href="${pageContext.request.contextPath }/cart?method=removeCart&pid=${entry.value.product.pid}" style="color:#FF0000; font-weight:bold">X</a>
</td>
</tr>
</table>
</c:forEach>
<table cellspacing="1" class="carttable">
<tr>
<td style="text-align:right; padding-right:40px;"><font
style="color:#FF6600; font-weight:bold">合计： ${cart.total }</font>
</td>
</tr>
</table>
<div style="text-align:right; margin-top:10px">
<a href="${ pageContext.request.contextPath }/product?method=findByPage2">
<!-- 继续购物 -->
<img src="images/gwc_jx.gif" border="0" />
</a>
<a href="order.jsp">
<!-- 结账 -->
<img src="images/gwc_buy.gif" border="0" />
</a>
</div>
</td>
</tr>
</table>
</td>
</tr>
</table></td>
</tr>
</table>
</div>
<jsp:include page="foot.jsp" />
</body>
</html>
CartServlet:
/**
* 点击X号，删除某一个购物项
* @param request
* @param response
* @throws ServletException
* @throws IOException
*/
public void removeCart(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
/**
* 获取商品的id
* 从session中获取购物车
* 从购物车中再获取map集合
* 通过id删除购物项
* 重新跳回到购物车的页面
*/
String pid=request.getParameter("pid");
HttpSession session=request.getSession();
Cart cart=(Cart) session.getAttribute("cart");
cart.getMap().remove(pid);
response.sendRedirect(request.getContextPath()+"/cart.jsp");
}
/**
* 点击+号，增加商品的数量
* @param request
* @param response
* @throws ServletException
* @throws IOException
*/
public void addCount(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String pid=request.getParameter("pid");
String sCount=request.getParameter("count");
int count=Integer.parseInt(sCount);
//判断
//获取购物车
HttpSession session=request.getSession();
Cart cart=(Cart) session.getAttribute("cart");
//获取购物车中的map集合，通过商品的主键获取到具体购物项
Map<String,CartItem> map=cart.getMap();
CartItem item=map.get(pid);
//判断,购买数量不能大于库存
if(count>item.getProduct().getPnum()){
//跳回购物车页面
response.sendRedirect(request.getContextPath()+"/cart.jsp");
return;
}
//更新数量
item.setBuyNum(count);
//跳回购物车页面
response.sendRedirect(request.getContextPath()+"/cart.jsp");
}
/**
* 点击-号，减少商品的数量
* @param request
* @param response
* @throws ServletException
* @throws IOException
*/
public void removeCount(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String pid=request.getParameter("pid");
String sCount=request.getParameter("count");
int count=Integer.parseInt(sCount);
HttpSession session=request.getSession();
Cart cart=(Cart) session.getAttribute("cart");
Map<String,CartItem> map=cart.getMap();
CartItem item=map.get(pid);
if(count<1){
response.sendRedirect(request.getContextPath()+"/cart.jsp");
return;
}
item.setBuyNum(count);
response.sendRedirect(request.getContextPath()+"/cart.jsp");
}
