XML购物车的实现（测试版）
序言：这篇文章会比较长，真正想了解的就得泡上一杯茶，慢慢阅读了！呵呵...
1.添加商品页面 add_goods.html
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body> <form action="cartAddGoodsRequest.do" method="post"> 购物（添加商品） <br> <table> <tr> <td align="right" style="width">商品ID：</td> <td><input type="text" name="goodsId"></td> </tr> <tr> <td align="right">商品所属分类：</td> <td><input type="text" name="goodsCatalog">(填数字:0 1 2)</td> </tr> <tr> <td align="right">商品价格：</td> <td><input type="text" name="goodsPrice"></td> </tr> <tr> <td align="right">购买件数：</td> <td><input type="text" name="purchaseNumber"></td> </tr> <tr> <td align="right">所属店主昵称：</td> <td><input type="text" name="shopkeeper" ></td> </tr> <tr> <td align="right">所属店铺名称：</td> <td><input type="text" name="shop"></td> </tr> </table> <input type="submit" value="提交" align="center"> </form></body></html> 说明：就是填写一些商品信息，后台是用struts处理的。至于struts的配置问题就不描述了。
2.添加商品请求由下面这个类进行处理： CartAddGoodsRequest
package cn.struts.action;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts.action.Action;import org.apache.struts.action.ActionForm;import org.apache.struts.action.ActionForward;import org.apache.struts.action.ActionMapping;import org.dom4j.Document;import org.dom4j.io.SAXReader;import cn.struts.formbean.PurchaseGoodsBean;/** * 购物车添加商品请求处理类 * @author LI * */public class CartAddGoodsRequest extends Action {public ActionForward execute(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response)throws Exception {System.out.println("购物车添加商品处理类");//参数对象（商品属性）PurchaseGoodsBean pgb=(PurchaseGoodsBean)form;System.out.println("id----"+pgb.getGoodsId()+"---shop---"+pgb.getShop());//获得session对象javax.servlet.http.HttpSession session=request.getSession();//获得购物车对象String cartString=(String)session.getAttribute("cart");Document cartXml=null;if(cartString!=null) cartXml = org.dom4j.DocumentHelper.parseText(cartString);//添加商品Document cart=cn.netjava.utils.XMLCart.getInstance().addGoods(pgb, cartXml);//购物车放入session中存放session.setAttribute("cart", cart.asXML());return null;}}
说明：1.首先从session中获得购物车对象，因为session里面存放的购物车是字符串形式(为什么，后面会讲)，需要转换成Document对象 。
2.添加商品处理，这里调用的是一个叫做XMLCart类的一个addGoods方法。稍等，下面我们就来看这个类！
3.将添加了新商品的购物车重新以字符串形式保存在session当中。
3.购物车操作类（往购物车里面添加商品，修改商品数量，删除商品，清空购物车）：XMLCart
package cn.netjava.utils;import java.util.Iterator;import java.util.List;import org.dom4j.Document;import org.dom4j.DocumentHelper;import org.dom4j.Element;import cn.struts.formbean.PurchaseGoodsBean;/** * XML实现的购物车 * @author LI * */public class XMLCart {//私有构造器private XMLCart(){};//单实例private static XMLCart instance=null;//获得该实例public static synchronized XMLCart getInstance(){//如果还没有被初始化if (instance==null){instance=new XMLCart();}return instance;}//创建购物车public Document createCart(){//使用DocumentHelper类创建一个文档实例，购物车对象Document cart=DocumentHelper.createDocument();//创建根元素cartorg.dom4j.Element cartRoot=cart.addElement("cart");//给根节点加子节点，代表购物车总金额Element totalMoney=cartRoot.addElement("totalMoney");totalMoney.setText("0");//给根节点加子节点，代表店主昵称@SuppressWarnings("unused")Element shopkeeper =cartRoot.addElement("shopkeeper");//给根节点加子节点，代表店铺名称@SuppressWarnings("unused")Element shop =cartRoot.addElement("shop");//商品列表@SuppressWarnings("unused")Element goodsList=cartRoot.addElement("goodsList");//返回购物车对象return cart;}/** * 清空购物车 * @param cart：购物车对象 */public Document emptyCart(Document cart){//获得根节点Element root=cart.getRootElement();//清空总资金Element totalMoneyNode=root.element("totalMoney");totalMoneyNode.setText(0+"");//清空店铺和店主Element shopNode=root.element("shop");shopNode.setText("");Element shopkeeperNode=root.element("shopkeeper");shopkeeperNode.setText("");//获得商品列表节点Element goodsListNode=root.element("goodsList");//遍历商品列表java.util.List<Element>goodList=goodsListNode.elements();for(int i=0;i<goodList.size();i++){//得到商品节点Element goodNode=goodList.get(i);goodsListNode.remove(goodNode);}return cart;}/** * 添加商品 * @param pgb：要添加的商品 * @param cart:购物车对象 */public Document addGoods(PurchaseGoodsBean pgb,Document cart){//如果购物车为NULLif(cart==null){//新建购物车对象cart=createCart();}if(pgb==null){return cart;}//获得根节点Element root=cart.getRootElement();//判断是否为同一店铺的商品booleansameShop=isSameShop(pgb,cart);//如果为不同店铺if(!sameShop){//清空购物车cart=emptyCart(cart);//设置店主昵称Element shopkeeperNode=root.element("shopkeeper");shopkeeperNode.setText(pgb.getShopkeeper());//设置店铺名称Element shopNode=root.element("shop");shopNode.setText(pgb.getShop());}//判断这件商品是否已在购物车里面boolean exist=isGoodsExist(pgb.getGoodsId(),cart);//如果已在if(exist){return cart;}else{//添加商品Element goodsListNode=root.element("goodsList");Element goodsNode=goodsListNode.addElement("goods");goodsNode.addElement("goodsId").setText(pgb.getGoodsId());goodsNode.addElement("goodsNumber").setText(pgb.getPurchaseNumber()+"");goodsNode.addElement("goodsCatalog").setText(pgb.getGoodsCatalog()+"");goodsNode.addElement("goodsPrice").setText(pgb.getGoodsPrice()+"");//操作数据库，根据商品ID获得商品的图片，名称，价格。//这里人工生成goodsNode.addElement("goodsPicture").setText("image/1.jpg");goodsNode.addElement("goodsName").setText("精致MP3");//设置商品积分int goodsIntegral=(int) pgb.getGoodsPrice()*pgb.getPurchaseNumber();goodsNode.addElement("goodsIntegral").setText(goodsIntegral+"");//设置每样商品资金小计double goodsTotalMoney=pgb.getGoodsPrice()*pgb.getPurchaseNumber();goodsNode.addElement("goodsSubtotal").setText(goodsTotalMoney+"");//获得当前总资金double totalMoney=Double.parseDouble(root.element("totalMoney").getText());//修改总金额double modifyTotalMoney=goodsTotalMoney+totalMoney;root.element("totalMoney").setText(modifyTotalMoney+"");}System.out.println(cart.asXML());return cart;}/** * 购买的商品是否属于同一店铺 * @param pgb:购买的商品属性 * @param cart：购物车 * @return：TRUE:属于同一店铺 FALSE:不属于同一店铺 */public boolean isSameShop(PurchaseGoodsBean pgb,Document cart){//获得根节点Element root=cart.getRootElement();//获得店主节点Element shopkeeperNode=root.element("shopkeeper");String shopkeeper=shopkeeperNode.getText();//如果没有店主if(shopkeeper==""){System.out.println("还没有店铺");//设置店主昵称shopkeeperNode.setText(pgb.getShopkeeper());//设置店铺名称Element shopNode=root.element("shop");shopNode.setText(pgb.getShop());return true;}else{System.out.println(" "+shopkeeper+" "+pgb.getShopkeeper());//如果是同一个 店铺if(shopkeeper.equals(pgb.getShopkeeper())){return true;}}return false;}/** * 修改商品数量 * @param pgb:商品对象 * @param cart：购物车对象 */public Document modifyPurchaseNumber(PurchaseGoodsBean pgb,Document cart){//获得根节点Element root=cart.getRootElement();//获得要修改的商品节点Element goodNode=getNode(pgb.getGoodsId(),cart);if(goodNode!=null){//得到商品數量迭代器Iterator goodsNumberIter=goodNode.elementIterator("goodsNumber");int goodsNumber=0;//获得商品数量if(goodsNumberIter.hasNext()){Element goodsNumberNode=(Element)goodsNumberIter.next();goodsNumber=Integer.parseInt(goodsNumberNode.getText());//修改商品的數量goodsNumberNode.setText(pgb.getPurchaseNumber()+"");}//商品数量的差量int goodsSub=pgb.getPurchaseNumber()-goodsNumber;//商品價格迭代器Iterator goodsPriceIter=goodNode.elementIterator("goodsPrice");double goodsPrice=0;//獲得商品價格if(goodsPriceIter.hasNext()){Element goodsPriceNode=(Element)goodsPriceIter.next();goodsPrice=Double.parseDouble(goodsPriceNode.getText());}//商品差价double goodsMoney=goodsPrice*goodsSub;//获得当前总资金double totalMoney=Double.parseDouble(root.element("totalMoney").getText());//修改总金额double modifyTotalMoney=goodsMoney+totalMoney;root.element("totalMoney").setText(modifyTotalMoney+"");//商品小计迭代器Iterator goodsSubtotalIter=goodNode.elementIterator("goodsSubtotal");Element goodsSubtotalNode=(Element)goodsSubtotalIter.next();//修改小计double goodsSubtotal=Double.parseDouble(goodsSubtotalNode.getText());double modifySubtotal=goodsSubtotal+goodsMoney;goodsSubtotalNode.setText(modifySubtotal+"");//修改获得积分Iterator goodsIntegralIter=goodNode.elementIterator("goodsIntegral");Element goodsIntegralNode=(Element)goodsIntegralIter.next();int goodsIntegral=(int)modifySubtotal;goodsIntegralNode.setText(goodsIntegral+"");}return cart;}/** * 获得指定ID商品的节点 * @param goodsId：商品ID * @param cart：购物车对象 * @return：指定ID的商品节点 NULL:没有这个节点 */@SuppressWarnings("unchecked")public Element getNode(String goodsId,Document cart){//获得商品列表节点List goodsList=cart.selectNodes("//goodsList/goods");//迭代器Iterator goodsIter=goodsList.iterator();while(goodsIter.hasNext()){Element goods=(Element)goodsIter.next();//得到商品ID迭代器Iterator goodsIdIter=goods.elementIterator("goodsId");while(goodsIdIter.hasNext()){Element goodsIdNode=(Element)goodsIdIter.next();if(goodsIdNode.getText().equals(goodsId))return goods;}}return null;}/** * 删除指定ID的商品 * @param goodsId：商品ID * @param cart：购物车对象 */public Document deleteGoods(String goodsId,Document cart){//获得根节点Element root=cart.getRootElement();//获得商品列表节点Element goodsListNode=root.element("goodsList");//获得要删除的节点Element goodNode=getNode(goodsId,cart);if(goodNode==null){return cart;}//获得小计Iterator goodsSubtotalIter=goodNode.elementIterator("goodsSubtotal");Element goodsSubtotalNode=(Element)goodsSubtotalIter.next();double goodsSubtotal=Double.parseDouble(goodsSubtotalNode.getText());//修改购物车总金额double totalMoney=Double.parseDouble(root.element("totalMoney").getText());double modifyTotalMoney=totalMoney-goodsSubtotal;root.element("totalMoney").setText(modifyTotalMoney+"");//删除节点goodsListNode.remove(goodNode);System.out.println(cart.asXML());return cart;}/** * 判断商品是否已经存在 * @param goodsId:商品ID * @param cart:购物车对象 * @return TRUE:存在 FALSE:不存在 */@SuppressWarnings("unchecked")public boolean isGoodsExist(String goodsId,Document cart){//获得根节点Element root=cart.getRootElement();//获得店主节点Element shopkeeperNode=root.element("shopkeeper");String shopkeeper=shopkeeperNode.getText();//如果没有店主if(shopkeeper==""){System.out.println("还没有店铺");return false;}//获得商品列表节点Element goodsListNode=root.element("goodsList");//遍历商品列表java.util.List<Element>goodList=goodsListNode.elements();for(int i=0;i<goodList.size();i++){//得到商品节点Element goodNode=goodList.get(i);//得到商品IDIterator goodsIdIter=goodNode.elementIterator("goodsId");Element goodsIdNode=(Element)goodsIdIter.next();String goodsID=goodsIdNode.getText();//如果存在这样的商品if(goodsId.equals(goodsID)){return true;}}return false;}} 说明：1.首先你得有dom4j这个解析XML文档的东东，如果感兴趣，到我的附件里面去下载
2.里面有的地方可能要操作数据库，比如根据商品的ID获得商品的图片，名称，价格等等，我这里就手工模拟了！
4.展示购物车商品信息的jsp页面 show_goods.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/xml" prefix="x"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><%@page import="org.dom4j.Document"%><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><!--引入外部js文件--><script src="js/jquery-1.3.2.min.js" type="text/javascript"></script><script src="js/detailInfo.js" type="text/javascript"></script><style TYPE="text/css"><!--A:link{text-decoration:none}A:visited{text-decoration:none}A:hover {color: #ff0000} --></style><title>Insert title here</title></head><body><c:out value="商品列表展示" /><br> <x:parse varDom="cartDoc">${cart}</x:parse><c:out value="总金额"/> <x:out select="$cartDoc/cart/totalMoney"/><br> <c:out value="店铺："/> <x:out select="$cartDoc/cart/shop"/><br> <c:out value="店主昵称："/> <x:out select="$cartDoc/cart/shopkeeper"/><br> <table border="1"> <tr> <td>商品图片</td> <td>商品名称</td> <td>商品ID</td> <td>商品购买数量</td> <td>商品所属分类</td> <td>商品价格</td> <td>可获得积分</td> <td>小计</td> <td>操作</td> </tr> <x:forEach select="$cartDoc//goods" varStatus="status"> <tr> <td> <img alt="" src="<x:out select="goodsPicture"/>"> </td> <td><x:out select="goodsName"/></td> <td><x:out select="goodsId"/></td> <td align="center"> <a href="" class="subNumber" id="<x:out select="goodsId"/>" name="<x:out select="goodsNumber"/>">-</a> <input id="goodsNumber" size="2" type="text" name="<x:out select="goodsId"/>" value="<x:out select="goodsNumber"/>"> <a href="" class="addNumber" id="<x:out select="goodsId"/>" name="<x:out select="goodsNumber"/>">+</a> </td> <td align="center"><x:out select="goodsCatalog"/></td> <td><x:out select="goodsPrice"/></td> <td><x:out select="goodsIntegral"/></td> <td><x:out select="goodsSubtotal"/></td> <td> <a id="<x:out select="goodsId"/>" href="" name="delete">删除</a> </td> </tr> </x:forEach> </table> </body></html> 说明：1. 这个页面用到了JSTL（用来展示商品信息）与jquery（用来发送异步请求，比如删除商品，修改商品数量）
想下载JSTL与jquery的 到附件下载
2.看看这段代码：<x:parse varDom="cartDoc">${cart}</x:parse> ${cart}:是从session当中取出购物车对象，在<x:parse>当中只能够为xml文件的字符串形式，这就是我为什么把购物车以字符串形式保存在session当中。
3.jquery处理异步请求，请参考下面的js文件
5.jquery AJAX发送异步请求（修改商品数量，删除商品） detailInfo.js
$(document).ready(function() {// 删除商品请求处理$("a").click(function(){alert($(this).attr("id"));//AJAX请求$.ajax({type:"post",url:"DeleteCartGoodsRequest.do",data:"goodsId="+$(this).attr("id"),success:function(msg){alert(msg);}});});//商品数量加一处理$("a").click(function(){//获得商品数量var goodsNumber=$(this).attr("name")*1+1;//获得商品IDvar goodsId=$(this).attr("id");alert(goodsNumber+"---id---"+goodsId);//AJAX请求$.ajax({type:"post",url:"ModifyCartGoodsRequest.do",data:"purchaseNumber="+goodsNumber+"&goodsId="+goodsId,success:function(msg){alert(msg);}});});//商品数量减一处理$("a").click(function(){//获得商品数量var goodsNumber=$(this).attr("name")*1-1;//获得商品IDvar goodsId=$(this).attr("id");alert(goodsNumber+"---id---"+goodsId);//AJAX请求$.ajax({type:"post",url:"ModifyCartGoodsRequest.do",data:"purchaseNumber="+goodsNumber+"&goodsId="+goodsId,success:function(msg){alert(msg);}});});//直接修改商品数量$("input").change(function(){//获得商品数量var goodsNumber=$(this).attr("value");//获得商品的IDvar goodsId=$(this).attr("name");alert(goodsNumber+""+goodsId);//AJAX请求$.ajax({type:"post",url:"ModifyCartGoodsRequest.do",data:"purchaseNumber="+goodsNumber+"&goodsId="+goodsId});});});
6.修改商品购买数量java后台处理类： ModifyCartGoodsRequest
package cn.struts.action;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts.action.Action;import org.apache.struts.action.ActionForm;import org.apache.struts.action.ActionForward;import org.apache.struts.action.ActionMapping;import org.dom4j.Document;import cn.struts.formbean.PurchaseGoodsBean;/** * 修改购物车某件商品数量处理类 * @author LI * */public class ModifyCartGoodsRequest extends Action {public ActionForward execute(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response)throws Exception {//参数类PurchaseGoodsBean pgb=(PurchaseGoodsBean)form;//获得修改后的商品数量与商品IDint purchaseNumber=pgb.getPurchaseNumber();String goodsId=pgb.getGoodsId();//调试信息System.out.println("修改后的商品数量为----->"+purchaseNumber+"goodsId--->"+goodsId);//获得session对象javax.servlet.http.HttpSession session=request.getSession();//获得购物车对象String cartString=(String)session.getAttribute("cart");Document cartXml=null;if(cartString!=null) cartXml = org.dom4j.DocumentHelper.parseText(cartString);//修改商品Document cart=cn.netjava.utils.XMLCart.getInstance().modifyPurchaseNumber(pgb, cartXml);//购物车放入session中存放session.setAttribute("cart", cart.asXML());return mapping.findForward("modifySucc");}} 这个就不必多做说明了，下面一个也一样
7.删除商品处理类： CartDeleteGoodsRequest
package cn.struts.action;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.apache.struts.action.Action;import org.apache.struts.action.ActionForm;import org.apache.struts.action.ActionForward;import org.apache.struts.action.ActionMapping;import org.dom4j.Document;import cn.struts.formbean.PurchaseGoodsBean;/** * 删除购物车里面的商品 * @author LI * */public class CartDeleteGoodsRequest extends Action {public ActionForward execute(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response)throws Exception {System.out.println("删除购物车里面的商品");//参数对象PurchaseGoodsBean pgb=(PurchaseGoodsBean)form;//调试信息System.out.println("goodsId---------->"+pgb.getGoodsId());//获得购物车对象HttpSession session=request.getSession();String cartString =(String)session.getAttribute("cart");Document cartXml=null;if(cartString!=null) cartXml = org.dom4j.DocumentHelper.parseText(cartString);//删除商品Document cart=cn.netjava.utils.XMLCart.getInstance().deleteGoods(pgb.getGoodsId(), cartXml);//购物车放入session中存放session.setAttribute("cart", cart.asXML());return mapping.findForward("deleteSucc");}}
OK,到此一切都弄好了！我基本上是Ctrl+C与Ctrl+V。呵呵...看不懂的地方，欢迎询问！如果认为哪个地方有更好的解决方法。欢迎交流！
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